by jgraham on 10/6/25, 7:46 PM
As someone who's been quite heavily involved with web-platform-tests, I'd caution against any use of the test pass rate as a metric for anything.
That's not to belittle the considerable achievements of Ladybird; their progress is really impressive, and if web-platform-tests are helping their engineering efforts I consider that a win. New implementations of the web platform, including Ladybird, Servo, and Flow, are exciting to see.
However, web-platform-tests specifically decided to optimise for being a useful engineering tool rather than being a good metric. That means there's no real attempt to balance the testsuite across the platform; for example a surprising fraction of the overall test count is encoding tests because they're easy to generate, not because it's an especially hard problem in browser development.
We've also consciously wanted to ensure that contributing tests is low friction, both technically and socially, in order that people don't feel inclined to withhold useful tests. Again that's not the tradeoff you make for a good metric, but is the right one for a good engineering resource.
The Interop Project is designed with different tradeoffs in mind, and overcomes some of these problems by selecting a subsets of tests which are broadly agreed to represent a useful level of coverage of an important feature. But unfortunately the current setup is designed for engines that are already implementing enough feature to be usable as general purpose web-browsers.
by daft_pink on 10/6/25, 6:05 PM
I think it’s just fantastic that the Ladybird browser is close to being usable. I was under the impression this was going to take many years before it became competitive.
by dotancohen on 10/6/25, 4:57 PM
The linked tweet notes that this is an important milestone in getting Ladybird considered as an alternative browser engine in iOS.
by pizlonator on 10/6/25, 5:20 PM
Super impressive that an independent, non-corpo project has gotten this far this quickly.
by d33 on 10/6/25, 9:12 PM
I just tried building and running it. Surprisingly many websites already load fine, though Youtube doesn't and Vimeo/Reddit comment section crashed it. Still, the results are quite encouraging! It takes ~6GB of HDD to build it.
by X0nic on 10/6/25, 5:28 PM
I wonder how hard the last 10% will be? If its a typical software project its going to be 90% more effort for the last 10%.
by lossolo on 10/6/25, 9:05 PM
What's the security story in Ladybird? Do they use sandboxes etc? I'm a bit concerned that hundreds of thousands of lines of C++ browser code written in just three years could be a minefield, but I hope I'm wrong.
by lenerdenator on 10/6/25, 6:48 PM
If nothing else, having an alternative engine with any amount of viability at all that isn't Blink is great news. I'll be interested to see how this progresses.
by flakiness on 10/6/25, 6:07 PM
There is a big jump in the graph! I wonder what contributed to that big improvement.
by Vipsy on 10/7/25, 7:09 AM
The WPT score is a flawed metric (encoding tests are overweighted), but it's one of the few objective yardsticks we have. What matters more is that Ladybird is finding spec ambiguities by implementing from scratch rather than cargo-culting Chrome's behavior.
The real test isn't passing 90%—it's whether they can keep pace as the web platform adds new APIs faster than any independent team can implement them. Browser engine development has become a regulatory moat, and breaking it requires either massive funding or accepting permanent incompatibility with the "modern web."
Still rooting for them. Browser monoculture is worse than metric gaming.
by Vipsy on 10/7/25, 7:08 AM
The WPT score is a flawed metric (encoding tests are overweighted), but it's one of the few objective yardsticks we have. What matters more is that Ladybird is finding spec ambiguities by implementing from scratch rather than cargo-culting Chrome's behavior.
The real test isn't passing 90%—it's whether they can keep pace as the web platform adds new APIs faster than any independent team can implement them. Browser engine development has become a regulatory moat, and breaking it requires either massive funding or accepting permanent incompatibility with the "modern web."
Still rooting for them. Browser monoculture is worse than metric gaming.
by guywithahat on 10/6/25, 7:15 PM
It's always struct me as interesting that ladybird is built with C++. I like C++, and prefer it to languages like Rust, but it's not uncommon to see new OSS projects using weird languages and the newest tools. Lots of languages offer improvements in regards to threading models, development speed, or cross-platform support which we don't get in C++.
I suppose their success is likely directly related to the fact they made reasonable, practical development choices, but still.
by XCSme on 10/6/25, 6:31 PM
What JS engine does it run on?
by scosman on 10/6/25, 5:39 PM
Me as engineer: it's wild a big corporation dictates a quality bar and limit API access for 3rd party software.
Me as customer: oh man I'm sure glad stuff is reviewed to some quality bar and the OS limits API access.
by zb3 on 10/6/25, 5:01 PM
So was there any app with an alternative browser engine already approved by Apple?
by bbminner on 10/6/25, 6:50 PM
Now that 90% of the work is done, it is only 90% of the work that remains :)
by jerf on 10/6/25, 6:16 PM
Thank you for the belly-laugh. It's Goodhart's Law in graph form.
"Oh, is this metric important? Let me get right on that."
No shade intended towards the Ladybird team. You were given the terms and you're behaving rationally in response to them. More power to you. It's just a fantastic demonstration of what it looks like to very suddenly be developing against a very specific metric.
by sn0n on 10/6/25, 10:52 PM
How's the ladybird gtk stuff coming along?
by everyone on 10/6/25, 9:15 PM
Oh yes cus Apple really care about the web.
by DeepYogurt on 10/7/25, 5:21 AM
You love to see it
by stronglikedan on 10/6/25, 5:36 PM
OT, but I really like the name Ladybird for a silly reason - it's the name of Hank Hill's dog. Whenever I hear it I think of her and smile. That's right, the thought of a cartoon dog makes me happy. I told you it was silly.
by liquid_thyme on 10/6/25, 6:39 PM
I wish them well, but browsers are very much pay-to-play. Google had to pay their way to their current dominant position.
by logicallee on 10/6/25, 9:55 PM