♥ JavaScript, HTML, CSS, HTTP, performance, security, Bash, Unicode, i18n.

Joined January 2007
389 Photos and videos
Pinned Tweet
At #io19, @_gsathya and I gave a talk on cutting-edge JavaScript features: youtube.com/watch?v=c0oy0vQK… ➡️ WeakRef ➡️ Intl.* ➡️ Promise.{allSettled,any} ➡️ numeric separators ➡️ Array#{flat,flatMap} ➡️ Object.fromEntries ➡️ String#matchAll ➡️ …and more!
47
145
565
Mathias Bynens retweeted
23 Sep 2025
Announcing @ChromeDevTools MCP! 🚀 Connect your AI coding agent to Chrome's powerful automation & debugging capabilities with ease. Key features: ✅ Reliable automation: It can programmatically handle clicks, form fills, dialogs, and page navigation with ease. ✅ Performance insights: Go beyond simple audits. Instruct your agent to record a performance trace and extract actionable insights to optimize your web apps. ✅ Advanced debugging: Empower your AI to analyze network requests, list console messages, take screenshots, and even evaluate scripts in the browser context. ✅ Browser emulation: Easily test different conditions by emulating CPU slowdowns, network throttling, or various screen sizes. Works well with modern web apps and believe this will unlock new workflows for automated testing, AI-driven debugging, and interactive web development. And there's much more to come!
74
297
1,782
268,477
Mathias Bynens retweeted
10 Sep 2025
Unicode 17 is released. The process for upgrading in js tooling is: 1. wait for @mathias to land unicode 17 in test262, e.g. github.com/tc39/test262/pull… 2. in js, upgrade to `@unicode/unicode-17.0.0`, e.g. github.com/babel/babel/pull/… 3. in Rust, upgrade github.com/oxc-project/unico…, which I maintain. blog.unicode.org/2025/09/uni… jenniferdaniel.substack.com/…
1
5
57
10,983
Mathias Bynens retweeted
Ever spent ages trying to figure out which element is actually scrolling on a page? #ChromeDevTools added a new scroll badge to help you spot them easier! Ionut & @jecfish will walk us through the technical implementation behind the scenes. Read: developer.chrome.com/blog/sw…
8
37
239
20,003
Mathias Bynens retweeted
✈️💺 Fasten your seatbelts! DevTools got a turbocharged upgrade with the new AI assistance panel. Debug styling issues, understand layouts, and fix airplanes. Ready for take-off? ➡️ developer.chrome.com/blog/5-…
13
56
9,818
Mathias Bynens retweeted
18 Oct 2024
Introducing AI Assistance in @ChromeDevTools! 🤯🚀 Ever wish you could have a coding buddy to help you with CSS and layout? Well, your wish is granted! The new AI Assistance in Chrome DevTools is here to make your life as a developer easier, powered by Gemini. The new panel aims to help you find and fix issues. Just ask it questions about your code, and it provides tailored explanations and even suggests solutions. This is our first exploration into agentic AI in DevTools and we're excited to hear what you think of it. Some key features: 1. Conversational prompts: Get tailored suggestions and code snippets. 2. Contextual understanding: AI understands the code you're working on. 3. Step-by-step guidance: Get help with everything from styling to debugging. Want to see it in action? Check out my screencast below to see how I used it to add a dark mode.
24
153
774
95,882
Mathias Bynens retweeted
✨ More Gemini is coming to DevTools! ✨ Try the new experimental AI assistance panel in Chrome Canary 131 and later to get help understanding layouts and debugging your CSS. Learn more at goo.gle/devtools-ai-assistan…
13
143
655
150,167
Mathias Bynens retweeted
📢 New post: The State of ES5 on the Web. For years, we defaulted to transpiling to ES5 in order to support IE. But is that still necessary? I took a look at the data to find out, and I'll just say that the results were *actually* quite surprising! 🙀 philipwalton.com/articles/th…
4
47
144
23,516
Mathias Bynens retweeted
15 Aug 2024
no pain syntax highlighting‽ - no JS - no markup transformation or tokenization how? via Colr Fonts 💪 try it! codepen.io/argyleink/pen/GRb…
27
126
765
176,634
Ahead of Defcon, the always-brilliant @SamyKamkar gave me a preview of his infrared laser spy tool: He can point a laser through a window at a laptop to detect its vibrations and derive the words typed on it from the acoustics of different keystrokes. wired.com/story/infrared-las…
11
119
322
59,463
Mathias Bynens retweeted
We’re pleased to announce that, as of version 23, the Puppeteer browser automation library now has first-class support for @Firefox! This means simplifying browser automation and testing across both @googlechrome and Firefox. 💻 hacks.mozilla.org/2024/08/pu…
86
318
30,786
Mathias Bynens retweeted
Very interesting idea by @keithamus of replacing CSS classes to custom tags (<my-card>), data-attributes and :state(). keithcirkel.co.uk/css-classe…
16
24
124
18,370
Mathias Bynens retweeted
After months of work its finally finished: 🔥 VISUAL EXPLAINS for MySQL: mysqlexplain.com Th cryptic output of MySQL's EXPLAIN is too hard to understand for any developer - even for me! So I built a tool to generate visual flows of whats happening. And its free! 🤯
31
169
726
223,537
Mathias Bynens retweeted
I wrote a tool called PySkyWiFi that gives you completely free, unbelievably stupid wi-fi on long-haul flights. It tunnels data through the "first name" field in your airmiles account, and can reach speeds of up to several bytes per second. robertheaton.com/pyskywifi
67
655
5,944
539,769
Mathias Bynens retweeted
Just published a Babel plugin for `regex`, allowing it to be used dependency-free. github.com/slevithan/babel-p… I'm new to Babel plugin development, so any help improving it is very welcome.
1
2
5
2,380
Mathias Bynens retweeted
`emoji-regex` is a great (and extremely widely used) package, but it's quite large since it hard codes thousands of code points. Just published `emoji-regex-xs` github.com/slevithan/emoji-r… which is a swap-in replacement that reduces uncompressed size by 97%.
3
6
18
3,533
Mathias Bynens retweeted
Launching: github.com/slevithan/regex-m… >> `import Regex from 'regex';` The new best way to create readable, high perf, modern native JS regexes, with best practices built-in and support for atomic groups, free spacing/comments, context-aware interpolation, more to come
1
2
10
2,328