WebAssembly from the Ground Up

Excited to announce the official launch of our online book, WebAssembly from the Ground Up! 🎉 It's the book we wish we'd had 3 years ago. No messing with tools and frameworks. It's a hands-on guide to the core of Wasm: the instruction set and module format. Link below. 👇

Hey friends, it's been a while! It's time for another summer sale — starting today, you can get the book for 50% off. Just head on over to wasmgroundup.com, no discount code required. So, if you've been meaning to pick it up (or you know someone who has), what better time than now?

In case you missed it last week, @dubroy.com was on CodeTV to show to talk about #Wasm with @jason.energy. It was a lot of fun! Worth a watch if you missed it live.

New post on the @ohmjs.org blog — Inside Ohm's PEG-to-Wasm compiler → ohmjs.org/blog/2026/03... v18 is now more than 50x faster for real-world grammars while using about 10% of the memory 🔥 …this post goes into the details of how it's built.

Tomorrow at 17:20 CET / 12:20 EDT / 9:20 PDT, I'll be livestreaming at twitch.tv/jlengstorf, teaching @jason.energy about WebAssembly!! I'll do my best to condense the best parts of our Wasm book (@wasmgroundup.com) into ~60 minutes. 😄

Ohhh this is cool: github.com/dy/jz JS syntax that compiles to pure WASM. No runtime, no GC.

TIL: Multithreaded WebAssembly → github.com/pdubroy/til/... (corrected)

A while back, someone in the @wasmgroundup.com Discord asked about resources for learning the formal notation used in the WebAssembly spec. One I like is Jeremy Siek's "Crash Course on Notation in Programming Language Theory": siek.blogspot.com/2012/07/cras...

Is it the end of February already?? Yes, yes it is. Which means we just sent out our #Wasm tidbits. Sign up here to get it in your inbox once a month (ish): sendfox.com/wasmgroundup

Spritely Hoot, our Scheme->WASM compiler (and all-around WASM toolkit) hits 0.8.0, and this one is a BIG release! spritely.institute/news/hoot-0-... For the first time you can LIVE develop web applications using Hoot, from the comfort of your own editor! See the video at the top!

"Wasm with TypeScript" oh hey that's us!!

**for early adopters** The WebRacket repo is now public at github.com/soegaard/web... The WebRacket language is a subset of Racket that compiles to WebAssembly examples github.com/soegaard/web... and racket-stories.com/static/minis... a small Scheme interpreter

Happy Friday! We just published a new blog post — A WebAssembly Interpreter: Part 2 → wasmgroundup.com/blog/wasm-vm... In the first post, we wrote a small #Wasm interpreter from scratch in JS. In Part 2, we extend the interpreter to support local and global variables.

Version 121 of Binaryen, the WebAssembly optimizer, is out: github.com/WebAssembly/... Compilation is now much faster on GC content, up to 2x.

Just sent out our #Wasm tidbits for January. All the coolest kids at FOSDEM subscribe, why don't you? https://sendfox.com/wasm...

We just sent out our last newsletter of the year, chock full of Wasm tidbits and captivating compiler content. Not signed up? You're missing out! Get on the list at sendfox.com/wasmgroundup

Are you sad that Advent of Code is already over, and looking for a new challenge to close out the year? Why not learn some #Wasm? Until Jan 7, you can get our book for 25% off! Just head to wasmgroundup.com and use the code HOLIDAY25.

A very readable doc about V8's new bytecode verifier. Readers of our book may notice the similarity to the Wasm security model — see this excerpt from the chapter "What makes WebAssembly safe?"

If you're into compilers or interested in low-level programming, don't miss @matt.godbolt.org's Advent of Compiler Optimizations! I've learned a few new things every day…Saturday's post was no exception: xania.org/202512/06-di...

I don't check LinkedIn very often, but today it was worth it. 😊

Oh hey! We're on the HN front page 😄 If you've read the book and enjoyed it, and feel like leaving a comment, it would certainly help us out!

Wasm Maze by Kenny Fully → kennyfully881230.github.io/wasm_fun/was... "I ended up learning a lot about how to use linear memory to render one time to the canvas on every frame. Not only that, I learn how to do collisions, sprite clipping etc all in Wasm." Source code: github.com/kennyfully88...

Per your request, please find enclosed…a new blog post! A WebAssembly interpreter (Part 1) → wasmgroundup.com/blog/wasm-vm... We build up a simple interpreter from scratch, in JavaScript, for a small subset of Wasm instructions (arithmetic and comparison).

This is something we thought about in our book…that's why the first (proper) chapter ends by producing a minimal (but valid) Wasm module.

Ever thought about writing #WebAssembly by hand? 🤔 Authors Patrick @dubroy.com and @marianoguerra.org think it's crucial for learning. They join #WasmAssembly host Thomas Steiner to discuss their ebook, "WebAssembly from the Ground Up" → goo.gle/3Ln67Pp

Today I presented to the Wasm CG a proposal for fine-grained dynamic code generation as a core WebAssembly feature. The proposal is now at phase 1! github.com/WebAssembly/... Also immortalized in song: suno.com/song/19e0679...

Working on a diagram for an upcoming @wasmgroundup.com blog post.

This week the W3C WebAssembly Community Group is holding an in-person meeting in Munich. We (@dubroy.com and @marianoguerra.org) are planning to be there. Patrick tomorrow, and both of us on Thursday for the Research Day. If you see us, come say hi!

📢 New #WasmAssembly podcast 🎙️ episode: #WebAssembly from the Ground Up with @dubroy.com and @marianoguerra.org. Learn how they're teaching #Wasm by building a compiler in JavaScript and why writing Wasm by hand is crucial! 🍿 www.youtube.com/watch?v=dRdD... 🎧 wasmassembly.libsyn.com/webassembly-...

Interesting paper presented at MPLR yesterday — "A Snapshot of the Performance of Wasm Backends for Managed Languages" → users.cs.northwestern.edu/~robby/pubs/... Benchmarks Wasm implementations of Dart, Haskell, Scheme, OCaml, Ruby against the native impls.

A look at how people are shipping Wasm as part of JavaScript libraries.

An interesting article about how Figma moved from WebGL to WebGPU — Figma rendering: Powered by WebGPU → www.figma.com/blog/figma-r... Also talks a bit about their overall app architecture, and how they use #wasm.

The WebAssembly 3.0 spec is complete! webassembly.org/news/2025-09... This includes major features like GC, 64-bit memories, exceptions, and tail calls.

@dubroy.com alerted me to the Safari release notes (developer.apple.com/documentatio...) say version 26 ships an in-place interpreter for WebAssembly, which is in part based on the Wizard design, but adapted for Safari's use cases. This is cool! Wasm brings all the VMs to tiers!

Nice use of Wasm — bundling lightweight WebAssembly decoders with the data. AnyBlox: A Framework for Self-Decoding Datasets → gienieczko.com/anyblox-paper /ht Jamie Brandon (www.scattered-thoughts.net/log/0054/)

Designing syntax is hard! Some good examples here of what makes language design so tricky.

Many of our friends in North America are back to school already, but we've still got two more weeks of holidays over here. Which means: it's not too late to snag a copy of the book in our summer sale!

Had a fun time recording a podcast episode today…looking forward to sharing it with y'all soon!

Lately I’ve been learning more about WebAssembly fundamentals by reading this fantastic book: wasmgroundup.com . It’s really well written and focuses on how WebAssembly is written by teaching you to write a compiler for it. Which is honestly pretty genius.

The summer holidays just started here in southern Germany. So, it's time for a ☀️ SUMMER SALE ☀️ — Use the code SUMMER25 for a 25% discount on the book until Sept 15: wasmgroundup.com

Wasm modules are enabled by default in the latest version of Node (v24.5.0)! 🎉

Pretty pleased with the ergonomics of the Wasm (macro-)assembler in @ohmjs.org. It's built on the low-level assembler lib we created for @wasmgroundup.com, but has some nice higher-level features, including labeled breaks. I'm particularly proud of the idea to put the block label at the end. 😊

WebAssembly Branch Hinting: From an idea to W3C standard → labs.leaningtech.com/blog/branch... An interesting look at journey from an idea ("it should would be nice if Wasm supported this…") to a standardized feature.

We're still looking for more sponsors! If you or your company can help fund this effort: github.com/sponsors/pd... Since 2017, my work on Ohm has been unpaid. Your sponsorship helps the project be sustainable, ensuring that I can maintain and improve Ohm for many years to come!

acm queue issue out on webassembly, with articles by @littledan.dev, conrad watt, ben titzer, & yours truly: queue.acm.org/issuedetail....

A good question we were asked recently — "Does V8 optimize WebAssembly similar to JS?" The latest post on the V8 blog, "Speculative Optimizations for WebAssembly using Deopts and Inlining", provides some answers! v8.dev/blog/wasm-s...

Here's what I've been working on the past couple months! It's been a lot of fun, and the prototype shows some promising perf improvements (~10x). It's still about 8–10 weeks of effort to productionize this. If you or your company can help fund that work, please get in touch!