Infrequently Noted

Alex Russell on browsers, standards, and the process of progress.

The Performance Inequality Gap, 2023

When digital is society's default, slow is exclusionary.

TL;DR: To serve users at the 75th percentile (P75) of devices and networks, we can now afford ~150KiB of HTML/CSS/fonts and ~300-350KiB of JavaScript (gzipped). This is a slight improvement on last year's budgets, thanks to device and network improvements. Meanwhile, sites continue to send more script than is reasonable for 80+% of the world's users, widening the gap between the haves and the have-nots. This is an ethical crisis for frontend.

Last month, I had the honour of joining what seemed like the entire web performance community at in Amsterdam.

The talks are up on YouTube behind a paywall, but my slides are mirrored here[1]:

The talk, like this post, is an update on network and CPU realities this series has documented since 2017. More importantly, it is also a look at what the latest data means for our collective performance budgets.

2023 Content Targets

In the interest of brevity, here's what we should be aiming to send over the wire per page in 2023 to reach interactivity in less than 5 seconds on first load:[2][3]

This implies a heavy JS payload, which most new sites suffer from for reasons both bad and beyond the scope of this post. With a more classic content profile — mostly HTML and CSS — we can afford much more in terms of total data, because JavaScript is still the costliest way to do things and CPUs at the global P75 are not fast.

These estimates also assume some serving discipline, including:

These targets are anchored to global estimates for networks and devices at the 75th percentile[4].

More on how those estimates are constructed in a moment, but suffice to say, it's messy. Where the data is weak, we should always prefer conservative estimates.

Based on trends and historical precedent, there's little reason for optimism that things are better than they seem. Indeed, misplaced optimism about disk, network, and CPU resources is the background music to frontend's lost decade.

Interaction-to-Next Paint measures page responsivness, and shows a large gap between desktop and mobile today
Per the 2022 Web Almanac, which pulls data from real-world devices via the CrUX dataset, today's web offers poor performance for the majority of users who are on mobile devices.

It is not an exaggeration to say that modern frontend is so enamoured of post-scarcity fairy tales that it is mortgaging the web's future for another night drinking at the JavaScript party.

We're burning our inheritance and polluting the ecosystem on shockingly thin, perniciously marketed claims of "speed" and "agility" and "better UX" that have not panned out at all. Instead, each additional layer of JavaScript cruft has dragged us further from living within the limits of what we can truly afford.

No amount of framework vendor happy talk can hide the reality that we are sending an escalating and unaffordable amount of JavaScript.
No amount of framework vendor happy talk can hide the reality that we are sending an escalating and unaffordable amount of JavaScript.

This isn't working for users or for businesses that hire developers hopped up Facebook's latest JavaScript hopium. A correction is due.


In years past, I haven't paid as much attention to the situation on desktops. But researching this year's update has turned up sobering facts that should colour our collective understanding.


From Edge's telemetry, we see that nearly half of devices fall into our "low-end" designation, which means that they have:

Add to this the fact that desktop devices have a lifespan between five and eight years, on average. This means the P75 device was sold in 2016.

As this series has emphasised in years past, Average Selling Price (ASP) is performance destiny. To understand our P75 device, we must imagine what the ASP device was at the P75 age.[5] That is, what was the average device in 2016? It sure wasn't a $2,000 M1 MacBook Pro, that's for sure.

No, it was a $600-$700 device. Think (best-case) 2-core, 4-thread married to slow, spinning rust.


Desktop-attached networks are hugely variable worldwide, including in the U.S., where the shocking effects of digital red-lining continue this day. And that's on top of globally uncompetitive service, thanks to shockingly lax regulation and legalised corruption.

As a result, we are sticking to our conservative estimates for bandwidth in line with WebPageTest's throttled Cable profile of 5Mbps bandwidth and ~25ms RTT.

Speeds will be much slower than advertised in many areas, particularly for rural users.


We've been tracking the mobile device landscape more carefully over the years and, as with desktop, ASPs today are tomorrow's performance destiny. Thankfully, device turnover is faster, with the average handset surviving only three to four years.


Without beating around the bush, our ASP 2019 device was an Android that cost between $300-$350, new and unlocked. It featured poor single and multi-core performance, and the high-end experience has continued to pull away from it since:

<em>Tap for a larger version.</em><br>Updated Geekbench five single-core scores for each mobile price point. TL;DR: your iPhone isn't real life.
Tap for a larger version.
Updated Geekbench five single-core scores for each mobile price point. TL;DR: your iPhone isn't real life.
<em>Tap for a larger version.</em><br>Android ecosystem <abbr title='system-on-chip'>SoC</abbr>s fare slightly better on multi-core performance, but the Performance Inequality Gap is growing there, too.
Tap for a larger version.
Android ecosystem SoCs fare slightly better on multi-core performance, but the Performance Inequality Gap is growing there, too.

As you can see, the gap is widening, in part because the high end has risen dramatically in price.

The best analogue you can buy for a representative P75 device today are ~$200 Androids from the last year or two, such as the Samsung Galaxy A50 and the Nokia G11.

These devices feature:

These are depressingly similar specs to devices I recommended for testing in 2017. Qualcomm has some 'splainin to do.

5G is still in its early diffusion phase, and the inclusion of a 5G radio is hugely randomising for device specs at today's mid-market price-point. It'll take a couple of years for that to settle.


Trustworthy mobile network data is challenging to acquire. Geographic differences create huge effects that we can see as variability in various global indexes. This variance forces us towards the bottom of the range when estimating our baseline, as mobile networks are highly contextual.

Triangulating from both and OpenSignal data (which has declined markedly in usefuleness), we're also going to maintain our global network baseline from last year:

This is a higher bandwidth estimate than might be reasonable, but also a higher RTT to cover the effects of high network behaviour variance. I'm cautiously optimistic that we'll be able to bump one or both of these numbers in a positive direction next year. But they stay put for now.

Developing Your Own Targets

You don't have to take my word for it. If your product behavior or your own team's data or market research suggests different tradeoffs, then it's only right to set your own per-product baseline.

For example, let's say you send more HTML and less JavaScript, or your serving game is on lock and all critical assets load over a single H/2 link. How should your estimates change?

Per usual, I've also updated the rinky-dink live model that you can use to select different combinations of device, network, and content type.

<em>Tap to try the interactive version.</em>
Tap to try the interactive version.

The Performance Inequality Gap is Growing

Essential public services are now delivered primarily through digital channels in many countries. This means what the frontend community celebrates and promotes has a stochastic effect on the provision of those services — which leads to an uncomfortable conversation because, taken as a whole, it isn't working.

Pervasively poor results are part of why responsible public sector organisations are forced to develop HTML-first, progressive enhancement guidance in stark opposition to the "frontend consensus".

This is an indictment: modern frontend's fascination with towering piles of JavasScript complexity is not delivering better experiences for most users.

For a genuinely raw example, consider California, the state where I live. In early November, it was brought to my attention that "felt slow", so I gave it a look. It was bad on my local development box, so I put it under the WebPageTest microscope. The results were, to be blunt, a travesty.

How did this happen? Well, per the new usual, overly optimistic assumptions about the state of the world accreted until folks at the margins were excluded.

In the case of, it was an official Twitter embed that, for some cursed reason, had been built using React, Next.js, and the full parade of modern horrors. Removing the embed, along with code optimistically built in a pre-JS-bloat era that blocked rendering until all resources were loaded, resulted in a dramatic improvement:

Thanks to some quick work by the team, the experience of the site radically improved between early November and mid-December, giving Californians easier access to critical information.

This is not an isolated incident. These sorts of disasters have been arriving on my desk with shocking frequency for years.

Nor is this improvement a success story, but rather a cautionary tale about the assumptions and preferences of those who live inside the privilege bubble. When they are allowed to set the agenda, folks who are less well-off get hurt.

It wasn't the embed engineer getting paid hundreds of thousands of dollars a year to sling JavaScript who was marginalised by this gross misapplication of overly complex technology. No, it was Californians who could least afford fast devices and networks who were excluded. Likewise, it hasn't been those same well-to-do folks who have remediate the resulting disasters. They don't even clean up their own messes.

Frontend's failure to deliver in today's mostly-mobile, mostly-Android world is shocking, if only for the durability of the myths that sustain the indefensible. We can't keep doing this.

As they say, any trend that can't continue won't.

  1. Apologies for the lack of speaker notes in this deck. If there's sufficient demand, I can go back through and add key points. Let me know if that would help you or your team over on Mastodon. ↩︎

  2. Since at least 2017, I've grown increasingly frustrated at the way we collectively think about the tradeoffs in frontend metrics. Per this year's post on a unified theory of web performance, it's entirely possible to model nearly every interaction in terms of a full page load (and vice versa).

    What does this tell us? Well, briefly, it tells us that the interaction loop for each interaction is only part of the story. Recall the loop's phases:

    1. Interactive (ready to handle input)
    2. Receiving input
    3. Acknowledging input, beginning work
    4. Updating status
    5. Work ends, output displayed
    6. GOTO 1

    Now imagine we collect all the interactions a user performs in a session (ignoring scrolling, which is nearly always handled by the browser unless you screw up), and then we divide the total set of costs incurred by the number of turns through the loop.

    Since our goal is to ensure users complete each turn through the loop with low latency and low variance, we can see the colourable claim for SPA architectures take shape: by trading off some initial latency, we can reduce total latency and variance. But this also gives rise to the critique: OK, but does it work?

    The answer, shockingly, seems to be "no" — at least not as practised by most sites adopting this technology over the past decade.

    The web performance community should eventually come to a more session-depth-weighted understanding of metrics and goals. Still, until we pull into that station, per-page-load metrics are useful. They model the better style of app construction and represent the most actionable advice for developers. ↩︎

  3. The target that this series has used consistently has been reaching a consistently interactive ("TTI") state in less than 5 seconds on the chosen device and network baseline.

    This isn't an ideal target.

    First, even with today's the P75 network and device, we can aim higher (lower?) and get compelling experiences loaded and main-thread clean in much less than 5 seconds.

    Second, this target was set in covnersation back in 2016 in preparation for a Google I/O talk, based on what was then possible. At the time, this was still not ambitious enough, but the impact of an additional connection shrunk the set of origins that could accomplish the feat significantly.

    Lastly, P75 is not where mature teams and developers spend their effort. Instead, they're looking up the percentiles and focusing on P90+, and so for mature teams looking to really make their experiences sing, I'd happily recommend that you target 5 second TTI at P90 instead. It's possible, and on a good stack with a good team and strong management, a goal you can be proud to hit. ↩︎

  4. Looking at the P75 networks and devices may strike mature teams and managers as a sandbagged goal and, honestly, I struggle with this.

    On the one hand, yes, we should be looking into the higher percentiles. But weaker goals aren't within reach for most teams today. If we moved the ecosystem to a place where it could reliably hit these limits and hold them in place for a few years, the web would stand a significantly higher chance of remaining relevant.

    On the other hand, these difficulties stack. Additive error means that targeting the combination P75 network and P75 device likely puts you north of P90 in the experiential distribution, but it's hard to know. ↩︎

  5. Data-minded folks will be keenly aware that simply extrapolating from average selling price over time can lead to some very bad conclusions. For example, what if device volumes fluctuate significantly? What if, in more recent years, ASPs fluctuate significantly? Or what if divergence in underlying data makes comparison across years otherwise unreliable.

    These are classic questions in data analysis, and thankfully the PC market has been relatively stable in volumes, prices, and segmentation, even through the pandemic.

    As covered later in this post, mobile is showing signs of heavy divergence in properties by segment, with the high-end pulling away in both capability and price. This is happening even as global ASPs remain relatively fixed, due to the increases in low-end volume over the past decade. Both desktop and mobile are staying within a narrow Average Selling Price band, but in both markets (though for different reasons), the P75 is not where folks looking only at today's new devices might expect it to be.

    In this way, we can think of the Performance Inequality Gap as being an expression of Alberto Cairo's visual data lessons: things may look descriptively similar at the level of movement of averages between desktop and mobile, but the underlying data tells a very different story. ↩︎

Apple Is Not Defending Browser Engine Choice

Gentle reader, I made a terrible mistake. Yes, that's right: I read the comments on a MacRumors article. At my age, one knows better. And yet.

As penance for this error, and for being short with Miguel, I must deconstruct the ways Apple has undermined browser engine diversity. Contrary to claims of Apple partisans, iOS engine restrictions are not preventing a "takeover" by Chromium — at least that's not the primary effect. Apple uses its power over browsers to strip-mine and sabotage the web, hurting all engine projects and draining the web of future potential.

As we will see, both the present and future of browser engine choice are squarely within Cupertino's control.

Apple's Long-Standing Policies Are Anti-Diversity

A refresher on Apple's iOS browser policies:

Defenders of Apple's monopoly offer hard-to-test claims, but many boil down to the idea that Apple's product is inferior by necessity. This line is frankly insulting to the good people that work on WebKit. They're excellent engineers; some of the best, pound for pound, but there aren't enough of them. And that's a choice.

"WebKit couldn't compete if it had to."

Nobody frames it precisely this way; instead they'll say, if WebKit weren't mandated, Chromium would take over, or Google would dominate the web if not for the WebKit restriction. That potential future requires mechanisms of action — something to cause Safari users to switch. What are those mechanisms? And why are some commenters so sure the end is nigh for WebKit?

Recall the status quo: websites can already ask iOS users to download alternative browsers. Thanks to (belated) questioning by Congress, they can even be set as the user's default, ensuring a higher probability to generate search traffic and derive associated revenue. None of that hinges on browser engine choice; it's just marketing. At the level of commerce, Apple's capitulation on default browser choice is a big deal, but it falls short of true differentiation.

So, websites can already put up banners asking users to get different browsers, If WebKit is doomed, its failure must lie in other stars; e.g., that Safari's WebKit is inferior to Gecko and Blink.

But the quality and completeness of WebKit is entirely within Apple's control.

Past swings away from OS default browsers happened because alternatives offered new features, better performance, improved security, and good site compatibility. These are properties intrinsic to the engine, not just the badge on the bonnet. Marketing and distribution have a role, but in recent browser battles, better engines have powered market shifts.

To truly differentiate and win, competitors must be able to bring their own engines. The leads of OS incumbents are not insurmountable because browsers are commodities with relatively low switching costs. Better products tend to win, if allowed, and Apple knows it.

Destkop <abbr>OS</abbr>es have long created a vibrant market for browser choice, enabling competitors not tied to OS defaults to flourish over the years.
Destkop OSes have long created a vibrant market for browser choice, enabling competitors not tied to OS defaults to flourish over the years.

Apple's prohibition on iOS browser engine competition has drained the potential of browser choice to deliver improvements. Without the ability to differentiate on features, security, performance, privacy, and compatibility, what's to sell? A slightly different UI? That's meaningful, but identically feeble web features cap the potential of every iOS browser. Nobody can pull ahead, and no product can offer future-looking capabilities that might make the web a more attractive platform.

This is working as intended:

<a href=''>Apple's policies</a> explicitly prevent meaningful competition between browsers on iOS. In 2022, you can have any default you like, as long as it's as buggy as Safari.
Apple's policies explicitly prevent meaningful competition between browsers on iOS. In 2022, you can have any default you like, as long as it's as buggy as Safari.

On OSes with proper browser competition, sites can recommend browsers with engines that cost less to support or unlock crucial capabilities. Major sites asking users to switch can be incredibly effective in aggregate. Standards support is sometimes offered as a solution, but it's best to think of it as a trailing indicator.[1] Critical capabilities often arrive in just one engine to start with, and developers that need these features may have incentive to prompt users to switch.

Developers are reluctanct to do this, however; turning away users isn't a winning growth strategy, and prompting visitors to switch is passé.

Still, in extremis, missing features and the parade of showstopping bugs render some services impossible to deliver. In these cases, suggesting an alternative beats losing users entirely.

But what if there's no better alternative? This is the situation that Apple has engineered on iOS. Cui bono? — who benefits?

All iOS browsers present as Safari to developers. There's no point in recommending a better browser because none is available. The combined mass of all iOS browsing pegged to the trailing edge means that folks must support WebKit or decamp for Apple's App Store, where it hands out capabilities like candy, but at a shocking price.

iOS's mandated inadequacy has convinced some that when engine choice is possible, users will stampede of away from Safari. This would, in turn, cause developers to skimp on testing for Apple's engine, making it inevitable that browsers based on WebKit and other minority engines could not compete. Or so the theory goes.

But is it predestined?

Perhaps some users will switch, but browser market changes take a great deal of time, and Apple enjoys numerous defences.

To the extent that Apple wants to win developers and avoid losing users, it has plenty of time.

It took over five years for Chrome to earn majority share on Windows with a superior product, and there's no reason to think iOS browser share will move faster. Then there's the countervailing evidence from macOS, where Safari manages to do just fine.

Regulatory mandates about engine choice will also take more than a year to come into force, giving Apple plenty of time to respond and improve the competitiveness of its engine. And that's the lower bound.

Apple's pattern of malaicious compliance will likely postpone true choice even futher. As Apple fights tooth-and-nail to prevent alternative browser engines, it will try to create ambiguity about vendor's ability to ship their best products worldwide, potentially delaying high-cost investment in ports with uncertain market reach.

Cupertino may also try to create arduous processes that force vendors to individually challenge the lack of each API, one geography at a time. In the best case, time will still be lost to this sort of brinksmanship. This is time that Apple can use to improve WebKit and Safari to be properly competitive.

Why would developers recommend alternatives if Safari adds features, improves security, prioritises performance, and fumigates for showstopping bugs? Remember: developers don't want to prompt users to switch; they only do it under duress. The features and quality of Safari are squarely in Apple's control.

So, given that Apple has plenty of time to catch up, is it a rational business decision to invest enough to compete?

Browsers Are Big Business

Browsers are both big business and industrial-scale engineering projects. Hundreds of folks are needed to implement and maintain a competitive browser with specialisations in nearly every area of computing. World-class experts in graphics, networking, cryptography, databases, language design, VM implementation, security, usability (particularly usable security), power management, compilers, fonts, high-performance layout, codecs, real-time media, audio and video pipelines, and per-OS specialisation are required. And then you need infrastructure; lots of it.

How much does all of this cost? A reasonable floor comes from Mozilla's annual reports. The latest consolidated financials (PDF) are from 2020 and show that, without marketing expenses, Mozilla spends between $380 and $430 million US per year on software development. Salaries are the largest category of these costs (~$180-210 million), and Mozilla economises by hiring remote employees paid local market rates, without large bonuses or stock-based compensation.

From this data, we can assume a baseline cost to build and maintain a competitive, cross-platform browser at $450 million per year.

Browser vendors fund their industrial-scale software engineering projects through integrations. Search engines pay browser makers for default placement within their products. They, in turn, make a lot of money because browsers send them transactional and commercial intent searches as part of the query stream.

Advertisers bid huge sums to place ads against keywords in these categories. This market, in turn, funds all the R&D and operational costs of search engines, including "traffic acquisition costs" like browser search default deals.[2]

How much money are we talking about? Mozilla's $450 million in annual revenue comes from approximately 8% of the desktop market and negligible mobile share. Browsers are big, big business.

WebKit Is No Charity

Despite being largely open source, browsers and their engines are not loss leaders.

Safari, in particular, is wildly profitable. The New York Times reported in late 2020 that Google now pays Apple between $8-12 billion per year to remain Safari's default search engine, up from $1 billion in 2014. Other estimates put the current payments in the $15 billion range. What does this almighty torrent of cash buy Google? Searches, preferably of the commercial intent sort.

Mobile accounts for two-thirds of web traffic (or thereabouts), making outsized iOS adoption among wealthy users particularly salient to publishers and advertisers. Google's payments to Apple are largely driven by the iPhone rather than its niche desktop products where effective browser competition has reduced the influence of Apple's defaults.

Against considerable competition, Safari was used by 52% of visitors to <abbr>US</abbr> Government websites from macOS devices from <time datetime='2022-03-06'>March 6<sup>th</sup></time> to <time datetime='2022-04-04'>April 4<sup>th</sup>, 2022</time>
Against considerable competition, Safari was used by 52% of visitors to US Government websites from macOS devices from to

The influence of a dozen years of suppressed browser choice is evident on iOS, where Safari is used 90% of the time. Apple's policies caused Mozilla to delay producing an iOS browser for seven years, and its de minimus iOS share (versus 3.6% on macOS) is a predictable result.
The influence of a dozen years of suppressed browser choice is evident on iOS, where Safari is used 90% of the time. Apple's policies caused Mozilla to delay producing an iOS browser for seven years, and its de minimus iOS share (versus 3.6% on macOS) is a predictable result.

iOS represents 75% of all visits to <abbr>US</abbr> Government websites from Apple <abbr>OS</abbr>es
iOS represents 75% of all visits to US Government websites from Apple OSes

Even with Apple's somewhat higher salaries per engineer, the skeleton staffing of WebKit, combined with the easier task of supporting fewer platforms, suggests that Apple is unlikely to spend considerably more than Mozilla does on browser development. In 2014, Apple would have enjoyed a profit margin of 50% if it had spent half a billion on browser engineering. Today, that margin would be 94-97%, depending on which figure you believe for Google's payments.

In absolute terms, that's more profit than Apple makes selling Macs.

Compare Cupertino's 3-6% search revenue reinvestment in the web with Mozilla's near 100% commitment, then recall that Mozilla has consistently delivered a superior engine to more platforms. I don't know what's more embarrassing: that some folks argue with a straight face that Apple is trying hard to build a good browser, or that it is consistently overmatched in performance, security, and compatibility by a plucky non-profit foundation that makes just ~5% of Apple's web revenue.

Choices, Choices

Steve Jobs launched Safari for Windows in the same WWDC keynote that unveiled the iPhone.

Commenters often fixate on the iPhone's original web-based pitch, but don't give Apple stick for reducing engine diversity by abandoning Windows three versions later.

Today, Apple doesn't compete outside its home turf, and when it has agency, it prevents others from doing so. These are not the actions of a firm that is consciously attempting to promote engine diversity. If Apple is an ally in that cause, it is only by accident.

Theories that postulate a takeover by Chromium dismiss Apple's power over a situation it created and recommits to annually through its budgeting process.

This is not a question of resources. Recall that Apple spends $85 billion per year on stock buybacks[3], $15 billion on dividends, enjoys free cash flow larger than the annual budgets of 47 nations, and retain tens of billions of dollars of cash on hand.[4] And that's to say nothing of Apple's $100+ billion in non-business-related long-term investments.

Even if Safari were a loss leader, Apple would be able to avoid producing a slower, stifled, less secure, famously buggy engine without breaking the bank.

Apple needs fewer staff to deliver equivalent features because Safari supports fewer OSes. The necessary investments are also R&D expenses that receive heavy tax advantages. Apple enjoys enviable discounts to produce a credible browser, but refuses to do so.

Unlike Microsoft's late and underpowered efforts with IE 7-11, Safari enjoys tolerable web compatibility, more than 90% share on a popular OS, and an unheard-of war chest with which to finance a defence. The postulated apocalypse seems far away and entirely within Apple's power to forestall.

Recent Developments

One way to understand the voluntary nature of Safari's poor competitiveness is to put Cupertino's recent burst of effort in context.

When regulators and legislators began asking questions in 2019, a response was required. Following Congress' query about default browser choice, Apple quietly allowed it through iOS 14 (however ham-fistedly) the following year. This underscores Apple's gatekeeper status and the tiny scale of investment required to enable large changes.

In the past six months, the Safari team has gone on a veritable hiring spree. This month's WWDC announcements showcased returns on that investment. By spending more in response to regulatory pressure, Apple has eviscerated notions that it could not have delivered a safer, more capable, and competitive browser many years earlier.

Safari's incremental headcount allocation has been large compared to the previous size of the Safari team, but in terms of Apple's P&L, it's loose change. Predictably, hiring talent to catch up has come at no appreciable loss to profitability.

The competitive potential of any browser hinges on headcount, and Apple is not limited in its ability to hire engineering talent. Recent efforts demonstrate that Apple has been able to build a better browser all along and, year after year, chose not to.

How Apple Gutted Mozilla's Chances

For over a dozen years, setting any browser other than Safari as the iOS default was impossible. This spotted Safari a massive market share head-start. Meanwhile, restrictions on engine choice continue to hamstring competitors, removing arguments for why users should switch. But don't take my word for it; here's the recent "UK CMA Final Report on Mobile Ecosystems" summarising submissions by Mozilla and others (pages 154-155):

5.48 The WebKit restriction also means that browser vendors that want to use Blink or Gecko on other operating systems have to build their browser on two different browser engines. Several browser vendors submitted that needing to code their browser for both WebKit and the browser engine they use on Android results in higher costs and features being deployed more slowly.

5.49 Two browser vendors submitted that they do not offer a mobile browser for iOS due to the lack of differentiation and the extra costs, while Mozilla told us that the WebKit restriction delayed its entrance into iOS by around seven years

That's seven years of marketing, feature iteration, and brand loyalty that Mozilla sacrificed on the principle that if they could not bring their core differentiator, there was no point.

It would have been better if Mozilla had made a ruckus, rather than hoping the world would notice its stoic virtue, but thankfully the T-rex has roused from its slumber.

Given the hard times the Mozilla Foundation has found itself in, it seems worth trying to quantify the costs.

To start, Mozilla must fund a separate team to re-develop features atop a less-capable runtime. Every feature that interacts with web content must be rebuilt in an ad-hoc way using inferior tools. Everything from form autofill to password management to content blocking requires extra resources to build for iOS. Not only does this tax development of the iOS product, it makes coordinated feature launches more costly across all ports.

Most substantially, iOS policies against default browser choice — combined with "in-app-browser" and search entry point shenanigans — have delayed and devalued browser choice.

Until late 2020, users needed to explicitly tap the Firefox icon on the home screen to get back to their browser. Naïvely tapping links would, instead, load content in Safari. This split experience causes a sort of pervasive forgetfulness, making the web less useful.

Continuous partial amnesia about browser-managed information is bad for users, but it hurts browser makers too. On OSes with functional competition, convincing a user to download a new browser has a chance of converting nearly all of their browsing to that product. iOS (along with Android and Facebook's mobile apps) undermine this by constantly splitting browsing, ignoring the user's default. When users don't end up in their browser, searches occur through it less often, affecting revenue. Web developers also experience this as a reduction in visible share of browsing from competing products, reducing incentives to support alternative engines.

A foregetful web also hurts publishers. Ad bid rates are suppressed, and users struggle to access pay-walled content when browsing is split. The conspicuious lack of re-engagement features like Push Notifications are the rotten cherry on top, forcing sites to push users to the App Store where Apple doesn't randomly log users out, or deprive publishers of key features.

Users, browser makers, web developers, and web businesses all lose. The hat-trick of value destruction.

Back Of The Napkin

The pantomime of browser choice on iOS has created an anaemic, amnesiac web. Tapping links is more slogging than surfing when autofill fails, passwords are lost, and login state is forgotten. Browsers become less valuable as the web stops being a reliable way to complete tasks.

Can we quantify these losses?

Estimating lost business from user frustration and ad rate depression is challenging. But we can extrapolate what a dozen years of choice might have meant for Mozilla from what we know about how Apple monetises the web.

For the purposes of argument, let's assume Mozilla would be paid for web traffic at the same rate as Apple; $8-15 billion per year for ~75% share of traffic from Apple OSes.

If the traffic numbers to US government websites are reasonable proxies for the iOS/macOS traffic mix (big "if"s), then equal share for Firefox on iOS to macOS would be worth $215-400 million per year.[5] Put differently; there's reason to think that Mozilla would not have suffered layoffs if Apple were an ally of engine choice.

Apple's policies have made the web a less compelling ecosystem, its anti-competitive behaviours drive up competitor's costs, and it simultaneously starves them of revenue by undermining browser choice.

If Apple is a friend of engine diversity, who needs enemies?

The Best Kind Of Correct

There is a narrow, fetid sense in which Apple's influence is nominally pro-diversity. Having anchored a significant fraction of web traffic at the trailing edge, businesses that do not decamp for the App Store may feel obliged to support WebKit.

This is a malignant form of diversity, not unlike other lagging engines through the years that harmed users and web-based businesses by externalizing costs. But on OSes with true browser choice, alternatives were meaningful.

Consider the loathed memory of IE 6, a browser that overstayed its welcome by nearly a decade. For as bad as it was, folks could recommend alternatives. Plugins also allowed us to transparently upgrade the platform.

Before the rise of open-source engines, the end of one browser lineage may have been a deep loss to ecosystem diversity, but in the past 15 years, the primary way new engines emerge has been through forking and remixing.

But the fact of an engine being different does not make that difference valuable, and WebKit's differences are incremental. Sure, Blink now has a faster layout engine, better security, more features, and fewer bugs, but like WebKit, it is also derived from KHTML. Both engines are forks and owe many present-day traits to their ancestors.

The history of browsers includes many forks and remixes. It's naïve to think that will end if iOS becomes hospitable to browser competition. After all, it has been competition that spurred engine improvements and forks.
The history of browsers includes many forks and remixes. It's naïve to think that will end if iOS becomes hospitable to browser competition. After all, it has been competition that spurred engine improvements and forks.

Today's KHTML descendants are not the end of the story. Future forks are possible. New codebases can be built from parts. Indeed, there's already valuable cross-pollination in code between Gecko, WebKit, and Chromium. Unlike the '90s and early 2000s, diversity can arrive in valuable increments through forking and recombination.

What's necessary for leading edge diversity, however, is funding.

By simultaneously taking a massive pot of cash for browser-building off the table, returning the least it can to engine development, and preventing others from filling the gap, Apple has foundationally imperilled the web ecosystem by destroying the utility of a diverse population of browsers and engines.

Apple has agency. It is not a victim, and it is not defending engine diversity.

What Now?

A better, brighter future for the web is possible, and thanks to belated movement by regulators, increasingly likely. The good folks over at Open Web Advocacy are leading the way, clearly explaining to anyone who will listen both what's at stake and what it will take to improve the situation.

Investigations are now underway worldwide, so if you think Apple shouldn't be afraid of a bit of competition if it will help the web thrive, consider getting involved. And if you're in the UK or do business there, consider helping the CMA help the web before July 22nd, 2022. The future isn't written yet, and we can change it for the better.

  1. Many commenters come to debates about compatibility and standards compliance with a mistaken view of how standards are made. As a result, they perceive vendors with better standards conformance (rather than content compatibility) to occupy a sort of moral high ground. They do not. Instead, it usually represents a broken standards-setting process.

    This can happen for several reasons. Sometimes standards bodies shutter, and the state of the art moves forward without them. This presents some risk for vendors that forge ahead without the cover of an SDO's protective IP umbrella, but that risk is often temporary and measured. SDOs aren't hard to come by; if new features are valuable, they can be standardised in a new venue. Alternatively, vendors can renovate the old one if others are interested in the work.

    More often, working groups move at the speed of their most obstinate participants, uncomfortably prolonging technical debates already settled in the market and preventing definitive documentation of the winning design. In other cases, a vendor may play games with intellectual property claims to delay standardisation or lure competitors into a patent minefield (as Apple did with Touch Events).

    At the leading edge, vendors need space to try new ideas without the need for the a priori consensus represented by a standard. However, compatibility concerns expressed by developers take on a different tinge over time.

    When the specific API details and capabilities of ageing features do not converge, a continual tax is placed on folks trying to build sites using features from that set. When developers stress the need for compatibility, it is often in this respect.

    Disingenuous actors sometimes try to misrepresent this interest and claim that all features must become standards before they are introduced in any engine. This interpretation runs against the long practice of internet standards development and almost always hides an ulterior motive.

    The role of standards is to consolidate gains introduced at the leading edge through responsible competition. Vendors that fail to participate constructively in this process earn scorn. They bring ignominy upon their houses by failing to bring implementations in line with the rough (documented and tested) consensus or by playing the heel in SDOs to forestall progress they find inconvenient.

    Vendors like Apple. ↩︎

  2. In the financial reports of internet businesses, you will see the costs to acquire business through channels reported as "Traffic Acquisition Costs" or "TACM". Many startups report their revenue "excluding TAC" or "ex-TAC". These are all ways of saying, "we paid for lead generation", and search engines are no different. ↩︎

  3. This is money Apple believes it cannot figure out a way to invest in its products. That's literally what share buybacks indicate. They're an admission that a company is not smart enough to invest the money in something productive. Buybacks are attractive to managers because they create artificial scarcity for shares to drive up realised employee compensation — their own included. Employees who are cheesed to realise that their projects are perennially short-staffed are encouraged not to make a stink through RSU appreciation. Everyone gets a cut, RSU-rich managers most of all. ↩︎

  4. Different analysts use different ways of describing Apple's "cash on hand". Some analysts lump in all marketable securities, current and non-current, which consistently pushes the number north of $150 billion. Others report only the literal cash value on the books ($34 billion as of

    The picture is also clouded by changes in the way Apple manages its cash horde. Over the past two years, Apple has begun to draw from this almighty pile of dollars and spend more to inflate its stock price through share buybacks and dividends. This may cast Apple as more cash-poor than it is. A better understanding of the actual situation is derived from free cash flow. Perhaps Apple will continue to draw down from its tall cash mountain to inflate its stock price via buybacks, but that's not a material change in the amount Apple can potentially spend on improving its products. ↩︎

  5. Since this post first ran, several commenters have noted a point I considered while writing, but omitted in order to avoid heaping scorn on a victim; namely that Mozilla's management has been asleep at the switch regarding the business of its business.

    Historically, when public records were available for both Opera and Mozilla, it was easy to understand how poorly Mozilla negotiated with search partners. Under successive leaders, Mozilla negotiated deals that led to payments less than as half as much per point of share. There's no reason to think MoCo's negotiating skills have improved dramatically in recent years. Apple, therefore, is likely to caputre much more revenue per search than an install of Firefox.

    But even if Mozilla only made 1/3 of Apple's haul for equivalent use, the combined taxes of iOS feature re-development and loss of revenue would be material to the Mozilla Foundation's bottom line.

    Obviously, to get that share, Mozilla would need to prioritise mobile, which it has not done. This is a deep own-goal and a point of continued sadness for me.

    A noble house reduced to rubble is a tragedy no matter who demolishes the final wall. Management incompetence is in evidence, and Mozilla's Directors are clearly not fit for purpose.

    But none of that detracts from what others have done to the Foundation and the web, and it would be wrong to claim Mozilla should have been perfect in ways its enemies and competitors were not. ↩︎

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