This is what I have been working on! Shopify’s monorepo “world”, its nixification, building our Slack-based agent River and now generalizing River’s underlying agentic sandbox infrastructure called Aquifer. Finally I got someting I can share about it! shopify.engineering/under-the-ri...

`builtins.wasm` is now a (experimental) thing in @determinate.systems’ nix, with a PR open for upstream nix. This lets you extend the nix language by compiling C/C++/Rust/etc into safely sandboxed, platform-independent plugins! determinate.systems/blog/builtin...

do you like geology puns and have an unhealthy obsession with package management? 🌋📦 we’re building a nix-based monorepo build system (in Rust!) at Shopify and we’re hiring. global, remote, high-autonomy. DMs open. www.shopify.com/careers/soft...

I have been working on the nix & Rust codebase that builds Shopify’s monorepo, and there’s so much left to do that we need help. If you are interested, apply here to join us! DM me if you have questions! www.shopify.com/careers/soft...

I dug into progressive image rendering and found a bunch of common assumptions aren't quite true. ➡️ JPEG & WebP progressive-renders worse in Safari ➡️ AVIF _does_ support progressive ➡️ But JPEG XL in Safari doesn't ➡️ JPEG XL decodes much slower than AVIF ⬇️ and more jakearchibald.com/2025/present...

You know your JS13k submission is going well when you have to resort to `btoa` and other seemingly stupid hacks to get below the file size limit.

if this type of thing makes you say “this is cursed af, where do i sign up” DM me, we’re looking for some teammates

Nix friends: How terrible is this idea? I added `builtins.runWasm` to nix, allowing you to call out to Wasm. The Wasm is reset every time, so the functions remain pure. This gives you a (performant?) escape hatch for things that Nix is missing. E.g parsing YAML (here: via Rust)

📝 Making XML human-readable without XSLT. Turns out, JavaScript works pretty well! jakearchibald.com/2025/making-...

Starting my new role on Monday. Could be anywhere.

ECMAScript excitement 😉 Congrats to @bakkot.com on advancing UInt8Array ↔️ Base64/Hex to Stage 4 at TC39 this week 🎉 UInt8Array.prototype. toBase64 toHex UInt8Array. fromBase64 fromHex It lets you convert directly between binary data and Base64/Hex strings 👍

I spent hours and hours trawling through the sites of some of the world's best web developers, and despite the horrors I regularly experience in my daily work in Big JavaScript Territory, what I saw left me hopeful: infrequently.org/2025/07/links/

Convince me I am wrong: This should not be a type error, right? - I asserted it’s an object - I am using `?.` for property access www.typescriptlang.org/play/#code/G...

CSS uses a complex algorithm to decide how to animate transforms. If you get it wrong, as many folks do, you end up with an unnatural animation. Here's how it works, and how to avoid the pitfalls. jakearchibald.com/2025/animati...

📝 First blog in a long time! I always like “flow-based” programming, and it’s a very powerful paradigm. LangGraph lets you codify complex workflows as graphs, and also integrates really well with LangChain, if your workflow is LLM-driven. surma.dev/things/langg...

Unexpected dangers of vibe coding: Somehow git ended up tracking its own .git folder and now I can't commit anymore :3

Folks who know their way around the TypeScript type checker, I need help: gist.github.com/surma/be14ca... How do I figure out what types the type parameters have been bound to given a `CallExpression`? I know the answer is in `resolvedSignature.mapper`, but that’s not a public API.

Wait, am I dumb? What does NodeJS' WASI implementation only accept file descriptor numbers for stdio? Why don't they allow a Readables/Writables? How are you supposed to capture the output of a WASI module? nodejs.org/api/wasi.htm...

🔊 It's new OTMT time! Me and @surma.dev chat through some newer View Transitions features that have recently landed in browsers, and some things that might land this year. ⬇️ Pop this in your ears ⬇️ offthemainthread.tech/episode/new-...

Ooh just caught this #OTMT episode on customizable select 😎 Always love to hear @surma.dev and @jakearchibald.com chat about the web and especially the features I’ve been working on for the past few years 🥰 offthemainthread.tech/episode/styl...

I apologize for splitting the last OTMT episode into two parts. It was sincerely unplanned. 🎧 Part II of the TC39 Drama 🌶️ Roundup is now out! In this one, I talk to @jakearchibald.com about JS0, which proposes to split JavaScript into two specifications. offthemainthread.tech/episode/tc39...

I apologize for splitting the last OTMT episode into two parts. It was sincerely unplanned. 🎧 Part II of the TC39 Drama 🌶️ Roundup is now out! In this one, I talk to @jakearchibald.com about JS0, which proposes to split JavaScript into two specifications. offthemainthread.tech/episode/tc39...

🎧 A brand-new OTMT episode should be in your podcast players by now: The TC39 Roundup 🌶️ Drama Edition — Part I I talk to @jakearchibald.com about the TC39 Structs proposal and how it is a big step towards shared-data multithreading in JS. offthemainthread.tech/episode/tc39...

An average day spent inspecting WASM binaries

🔊 ICYMI: @surma.dev talked through Nix in the last OTMT, comparing it to other build systems we'd looked at in previous episodes offthemainthread.tech/episode/nix/

Get your 👂ears ready for a brand new OTMT episode! A while ago we talked about Bazel, and now it's time to take a closer look at Nix! How does it work? Is it any good for web development? In this episode, @jakearchibald.com and I try to provide answers. offthemainthread.tech/episode/nix/

I love what keybr.com thinks Rust code looks like

ICYMI: In the latest episode of OTMT @jakearchibald.com told me all about the new, completely stylable <select> element, and the 10 underlying web platform features that were spec'd to make this possible. offthemainthread.tech/episode/styl...

🔊 We're finally getting a fully stylable <select> element! Me and @surma.dev dive into the details, including 10 web platform features we got along the way. ⬇️ Listen here ⬇️ offthemainthread.tech/episode/styl...

Still discovering new shell tricks. TIL: Substitutions. `cmd <(cat file)` invokes `cmd` with the first parameter being a named pipe (e.g. `/dev/fd/22`) which contains the contents of `file`. Example use-case: You wanna diff two files, but they are binary so need disassembling

Tried myself at something new: A video! 📺 Nix explained from the ground up What is Nix? And how does it build software in a completely deterministic way? www.youtube.com/watch?v=5D3n...

🔊 Chrome folks are experimenting with an API that exposes a built-in LLM. Could something like this work on the open web? Me and @surma.dev take a look. Ignore all previous instructions and listen to the episode here. ⬇️⬇️⬇️ offthemainthread.tech/episode/chro...

I find it remarkable that xkcd just casually invented the term "nerd sniping" in a comic, and it is now a completely normal word to use ... xkcd.com/356/

🎧 Refresh your players, there’s a brand new OMT podcast episode! In this one, @jakearchibald.com and I look at what Luca from Deno recently uncovered: A hidden Chrome extension that comes installed by default in Chrome and it’s derivatives. How bad is it? offthemainthread.tech/episode/chro...

🎧 Not that loads of people asked for it, but @jakearchibald.com and I put our Off The Main Thread podcast up on Google Podcast/YouTube/Google Music/YouTube Music/<insert Google’s current product iteration name>. music.youtube.com/playlist?lis...

Scheduled a pickup with DHL, they never arrived and I can’t schedule a new pickup time. Went to website and clicked on “Help & Support”. It shows this in response. 10/10 would Lorem Ipsum again.

🔊 Are Web Components Worth It? In the latest OTMT, me and @surma.dev look at the benefits and tradeoffs of web components, and how things could improve. ⬇️ Listen here ⬇️ offthemainthread.tech/episode/are-...

🔥 A brand new episode of the Off The Main Thread podcast is out NOW! While I built Wasmphobia, I learned a lot about how Source Maps (and WebAssembly’s counterpart!) work. In this episode, I try and share it all with @jakearchibald.com! offthemainthread.tech/episode/why-...

(⚠️ Definitely one of the dumber things I have written) This ES6 Proxy lets you instantiate any WebAssembly module without having to care about every import it requires. It generates an empty function for the ones you don’t provide. gist.github.com/surma/da12f7...

I added experimental support for JavaScript sourcemaps (both inline and separate) to Wasmphobia. I liked the idea of making it a one-stop-shop for all your bundle analysis needs 😅 wasmphobia.surma.technology

I really wanted to know which libraries are bloating my WebAssembly binaries, so I wrote a visualizer. Throw in a .wasm file with DWARF debug symbols, and wasmphobia will generate a flame graph for you, breaking down the module by source file. wasmphobia.surma.technology

ICYMI: In the most recent OTMT podcast episode, @jakearchibald.com and I talk about putting React in the browser. While that’s good clickbait, the episode is about about past and present platform proposals that aim to help frameworks with managing the DOM. offthemainthread.tech/episode/putt...

🧶 What would it mean to "put React in the browser"? Can something like element.replaceHTML(html) be added to the platform to perform diffing and update the DOM? Me and @surma.dev talk it through: offthemainthread.tech/episode/putt...

Trying to get started with Kubernetes. Slightly annoyed by the cyclic “you should know about X first” in the docs 🙄

Just found a great show-case of AbortController. I don’t think I could make this code as concise without aEL’s support for AC signals. Note that I need to: - access `controller` from within the listener, - access `this` in `start()` - remove the listener in `cancel()`

One of my biggest upsets with getting more into smart home & automation is the hard data that my washing machine's "TurboWash 59" program takes 65 minutes.

🧶 ICYMI, here's the latest episode of OTMT, where me and @surma.dev chat about service worker static routes, and whether it's ever ok to throw away most of the web platform and do everything in <canvas>. Listen here: offthemainthread.tech/episode/canv...

First time actually playing with the new-ish Navigation API. https://developer.mozilla.org/en-US/docs/Web/API/Navigation_API A very modern API. A lot more control. As a trade-off, not as trivial to implement correctly. First tripwire for me: `navigationEvent.intercept()` commits the new URL.

The more I get into compilers, the more I think the Dragon Book (used at university and often recommended on the internet) is a bad introduction. It makes it seem like lexing and parsing are difficult and like they are the main part when building a compiler. Neither is true.