The current link is just the release notes and covers only the interface-level changes. The announcement post goes into more detail on what's new in WASI 0.3, how it differs from WASI 0.2, and includes examples.
Love/hate with this one. How was I supposed to follow this? I tried, and few things were publicly visible for nearly two years. I last checked in march and it looked like no progress had been made.
That makes me very suspicious of wasiv3. Funny enough, I already implemented a bunch of the promises (pun not intended) and think that freestanding wasm with custom integrations is the more likely future.
The promise of wasi components has not been fulfilled. The market wants to hotload and link artifacts dynamically. The wasi project requires insider wizardry to use it that way: the offering has been statically linking components before you ship. Defeating 99% of the use cases.
I do not like that this has been worked on in the shadows.
I don't think it's fair to say this work has happened in the shadows. I work on CNCF wasmCloud, and I know how hard we try to make this content available.
I mean this, though - what else would you like to see to try and make the content and process more accessible? Are there communities that are doing this really well that we could use for inspiration?
At 18:00 the speaker states something like "It should not be Systems Interface but Standard Interfaces" which honestly sounds like a different project. As an implementer or even as just a user in general, can it be trusted that tomorrow it isn't something completely different? Seems like an odd standard to follow.
(EDIT and aside: Rereading this it reads more dismissive than I meant it. So if this isn't clear: I want WASI to succeed. I think having a widely used system interface is great, but I think many know standards that suffered from scope creep. And while big successful standards for better or for worse at least have a chance of surviving this, WASI as the 0.3 indicates is in its infancy. So I worry about it turning out bad, leading to people abandoning the idea altogether or the standard losing sight of its initial goal. So while this is criticism the only reason I bother to write it in first place is because I badly want it to succeed. I worry that if WASI tries to do too much at once - and I totally understand wanting to do that - it makes it less likely to be successfully implemented and thereby less likely to succeed as a standard.)
Wrong direction. WASI should be simple and stable. Initially, it was revolving around a simple Unix-like API model and it was close to perfect. Now, there is an opinionated component model which is an unneeded overcomplication that should have never been considered as part of WebAssembly spec IMHO.
A real component model is a separate development and cannot be blindly tied to a particular ecosystem. Otherwise, its main purpose of providing easy interoperability between different ecosystems is totally lost.
I do not know why WebAssembly committee thinks that shoving-in CORBA-like monstrosity is even an acceptable idea. Let's keep WebAssembly lean and fast! Anything extra can (and should) be implemented by other technologies.
The component model is what unlocks relatively type-safe interop between modules written in different languages. Given that Wasm is a runtime target for many languages, this is an entirely appropriate and useful goal.
If you have a host system where you want to expose APIs in an language-agnostic way, IDLs are the best way to do that.
You're also conflating the core WebAssembly work with the WASI work. There is some overlap in people, but WASI is developed separately.
There is a wat (s expression) syntax for the component model. The problem with the wat syntax for both Wasm and the component model is they’re a reflection of a binary format, and therefore are terrible for writing by hand. They’re designed to be written by tools, and the text format is just to help you understand the binary format.
I’ve written Wasm and component model wat extensively over the last decade to develop tests for Wasmtime, and even for an expert it’s a bad experience.
Wit syntax is easy to read and write by hand. There are high quality parsers that can transform it to and from the binary or wat format as needed, and code generators for a wide range of languages. It’s a way, way better experience in every way to deal with wit compared to the wat format.
The present component model is "simple and stable". It is presently providing "interoperability between different ecosystems" and has been for years. It has basically nothing in common with CORBA. All the major problems with the Unix design they ran into that caused them to switch to a component model haven't vanished; the component model is still the best way of solving WASM's major complications that traditional C-based designs don't have. C-based designs, in general, are not better just because they came first; if you were designing systems programming from scratch, you'd want something like WIT (proof: Microsoft has done this twice now).
AIUI, the underlying motivation for the WASM component model is the same as for the early interface types proposal, which has been a planned part of WASM since the very beginning - namely to allow modules written in high-level languages to expose "native" interfaces, without requiring a completely bespoke translation into WASM's lower level facilities. That's a sensible goal, even if achieving this may ultimately involve something that's at least loosely reminiscent of CORBA.
i don't think people calling it CORBA-like are doing it in good faith, but regardless, no we should not do unix apis everywhere for the rest of time please
I agree. This is saddening. It seems to often happen in "standard first" scenarios for some reason. I was very happy when CloudABI and POSIX were picked as prior art inspiration.
Now it feels like it moved from "what would we need to get things done and achieve our goals?" to "what could be done and which goals could we achieve?"
Maybe I am missing something, but are the recent changes something that people requested?
Yes, you missed people asking for years: away to do interop between languages in WASM, a way to interact with browser APIs without JavaScript from WASM.
Fair enough. Isn't that another topic more tied to WASM compare to what initially claimed to be a "System Interface" and not a language interface or a browser interface?
I think there is a difference between "just copying" and "building upon understood systems and standards".
Also to be fair "just copying" works really really well, especially for standards. The primary goal of standardization is not to invent something new, but to have a target that isn't constantly moving.
If you want to build something new and better do that, and if you are ready to build a standard based of it which is very valid. You can also build them together, and CloudABI which they mention as inspiration in their readme for example did it that way. All valid paths.
But you want to start out simple and something common so that people that make use of the standard have an easy time to implement it. After all having more than one implementation is why you need a standard. Otherwise it's maybe a specification, which again, fair enough.
I can stand behind not copying Unix until the end of time, but "Unix" is a common target that people know how to implement and use. And while not even the authors of Unix claim it's great or even good it is something that people already implement (often enough even when not targeting anything unixy at all) so if your goal is to create a standard that those people can target then abandoning that does seem like a wrong move.
Even if something lasts due to pure inertia it lasts. And something that lasts is pretty nice if you want a standard to last, or be implemented. The standard usually isn't the thing that you use to proof you can do something better, by being different. Because then everyone will have a harder time adapting it. People implement interfaces they dislike.
Since this is related to Webassembly, Browsers, the Web. The web has a lot of historically baggage, that one might have to work around at times, sometimes more sometimes less. There are good bits and not so good bits and in the end a lot of the time more modern web applications (whether you think they are good or bad) as well as web browsers jump through hoops to do things. For many applications there would be better protocols. But it became the dominant standard, a standard that is actually being used a lot and that is why it has become a success story. It wasn't a hundred times better than everything else. It simply was something that people managed to implement successfully and something where they were willing to deal with shortcomings, because there are great benefits in implementing the same standard as everyone else.
Don't know much about the US constitution, but it seems that it was largely good enough to make people work together that otherwise might have ended up fighting each other. That's what you'd get if everyone had a different idea about what a good constitution is. Maybe things are unclear, and maybe there are uproars because of things, but it doesn't even get to that if people don't agree on a standard or a constitution in first place.
And while over the years I often imagined how great it would be if everyone just used that better standard that has been there for a long time and nobody uses and is completely forgotten, if it ever had any popularity, then everything would be so much better and greater and I wouldn't have to do that senseless thing I am doing now. But if that standard doesn't allow for people to agree with it by implementing it it's essentially worthless (outside of maybe "prior art" consideration).
And like it or not we currently live in a world where designs persist due to pure inertia. But we know that obviously people are willing to implement these which means when a standard comes along that is similar to what already is there then having many people adapting it is realistic. Otherwise it's that super interesting university project that never makes it into anything in the real world.
If you have used WASI in the past, can you mention your use case? Very curious if you found it to give you an edge compared to other sandboxing like containers or VMs.
WASI is the best format for code submitted by users, entirely untrusted, which is in principle of any complexity but expected to be pretty simple. It works on any platform, in any environment, with extreme and direct control over its access to every resource and its ability to execute at all. Wasmtime's "fuel" feature is not something you can do with containers, and if you can do it with VMs then I don't know about it, but VMs are behemoths for the task of executing a simple function that would in an alternate universe be CEL.
I tinkered with https://extism.org and basically the use case is that they suggest, namely you can extend software in another programming language but without having to setup a container or VMs on the client. They "just" run the code in the browser and it can be JavaScript, sure, but can also be Python, Go, whatever.
It's quite specific though as I'm working on support programming in the browser.
If you are not deep into letting a very specific kind of user extend, it's probably overkill.
Even then it's a very VERY niche thing because it has to be simultaneously :
- someone who is opinionated about a programming language (either because they know too much, i.e. expert, or not enough, i.e beginner)
- is dedicated enough to want to try to build something on top of an existing system
- does not want to bother with solutions you mentioned
We evaluated Extism and concluded that it did basically nothing that WASI and the component model didn't already do out of the box. Was your experience different?
In-process sandboxed llm-generated code execution. Considerably lighter weight, faster to boot (assuming pre-compilation) than Docker or spinning up micro-VMs.
I'm using it for a secure, language agnostic workflow orchestrator. Components have very finely-grained and controller permissions and access to data. They don't even get clocks by default (to mitigate against Spectre-style attacks) and credentials and tainted data are sequestered.
Will WebAssembly ever achieve a real breakthrough? It's been almost 10 years since it came around. HTML, CSS and JavaScript were a breakthrough back in the days. WebAssembly still is not right now; only very few folks or companies use it.
I think its killer use case is actually embedded in non-web places. Tree Sitter parsers require arbitrary programs to be able to parse arbitrary languages. WebAssembly is a natural way to achieve that: write your parser in any language, compile to WebAssembly, use that result in any supported editor. You get sandboxed execution and arbitrary compute.
It has to compete with more domain-adapted use cases though. Does WASM make more sense than eBPF for packet filtering? It doesn't seem to make more sense than JavaScript for making websites. Maybe it makes more sense for deploying edge services (which IIUC is the main use case for WASI).
Plugin architectures are a niche where WASM really shines. Before WASM most plugins were either high performance (loading dynamic libraries) or sandboxed and safe for untrusted plugins (LUA etc). WASM allows you to have your cake and eat it to. You pay with a bit of complexity, but it's in a great and somewhat unique place in the tradeoff space
I think I've seen you comment this on every recent WASM post, and I'm really wondering what you think breakthrough success looks like for a low-level technology like WASM?
Do you expect everyone to hand-code their websites in WASM? Do you expect every webapp be cross-compiled to WASM?
From where I'm standing, WASM is extremely successful in its specific niches: in enabling islands of high-performance in otherwise web-based software, and in sandboxing plugins to native apps/servers.
Many things are possible that weren't possible before. For example, I was able to compile the Dart VM (the compiler + analyzer + VM) to wasm and run it on the web: https://github.com/modulovalue/dart-live it supports hot reload and many other cool features. It runs essentially everywhere and it's a very bare proof of concept for a fully integrated programming development system.
The problem is that things just take time if you have to coordinate across a bunch of languages and teams while trying to make everyone happy.
To give you a sense of what else is coming: the wasm ecosystem is moving towards supporting a component model. Eventually you'll be able to import any piece of code from any programming language that supports it. Wasm interface types will make that possible.
> I was able to compile the Dart VM (the compiler + analyzer + VM) to wasm and run it on the web
Is this really a representative use-case of WASM/WASI? Would'n it be much better to compile Dart to WASM (the Dart SDK even supports "dart compile wasm")?
It's a silent technology, but I'd argue it has broken through in that most of us already use it daily without knowing. Figma, Google Sheets, Disney+, Prime Video, and much more all have WebAssembly somewhere in their stack.
It's used heavily by major web apps like Figma, it's used to run non-Javascript languages on Cloudflare Workers, many compute-heavy web libraries rely on Wasm modules, many web games rely on Wasm, it's used for safe plugins in some native apps like Microsoft Flight Simulator, amongst other use cases.
My task in question was a number crunching task, basically doing multiply-and-add for 336-bit integers. I wrote a JS version, and a C version compiled into WASM by using Zig. You'd think that WebAssembly would trounce JS here, but it actually didn't.
The JS code had been written carefully to avoid allocations, and also avoiding the built-in JavaScript BigInt. I rolled my own BigInt instead using an array of numbers. Each number, despite being a double, was basically a 48-bit integer. Long multiplication requires splitting a 48-bit integer into two 24-bit integers so an intermediate multiplication result will fit in 48 bits.
The C version used 32x32=64-bit integer math. (Would have been nice if WASM had supported 64x64=128-bit multiplication)
Even with the overhead of using doubles instead of integers, the JavaScript and C versions ran at nearly the same speed. I think the C version was slightly faster, but not significantly. The C version took a lot longer to load, as it had to instantiate a Webassembly object, and had to run glue code to copy things in and out of Webassembly memory.
Just allowing more than one arraybuffer could go a long way to help with performance. One array buffer for the wasm memory space, then an arraybuffer for each input or output argument.
I mean, it’s another tool. It doesn’t really make an entirely new kind of web app possible, but it’s useful for some specific compute-heavy tasks (with limitations like JS<->WASM being slow). It’s also useful for running not-JS in the browser; I’m building a lighting console with a web UI distributed over multiple devices, and being able to use the exact same structs/representation and algorithms on server and client is pretty neat. It’s like Node, but in reverse! But none of this is cause for paradigm shift, so I don’t think seeing a ”breakthrough” really is relevant.
This! The only way to get to a stable system at least with c/c++ source, where you can hunt bugs, is to have a fairly large unit test coverage. When something fails - add that as test case; run ctest - pray that this is discoverable with tests.
So wasm is a really strange compilation target for systems programming languages.
I mean there _are_ ways to debug it in a browser but they sort of suck.
I'm building a game where you learn to program golang or python and it all runs in webassembly, this way any student chromebook can just pick up and go.
That feels pretty revolutionary, no need to setup your local system to get core concepts.
Even have plans to use postgres in WASM (pglite), and I know a few real time apps use sqlite in WASM.
Hey everyone, we just published the announcement post for WASI 0.3 on the Bytecode Alliance blog:
https://bytecodealliance.org/articles/WASI-0.3
The current link is just the release notes and covers only the interface-level changes. The announcement post goes into more detail on what's new in WASI 0.3, how it differs from WASI 0.2, and includes examples.
Love/hate with this one. How was I supposed to follow this? I tried, and few things were publicly visible for nearly two years. I last checked in march and it looked like no progress had been made.
That makes me very suspicious of wasiv3. Funny enough, I already implemented a bunch of the promises (pun not intended) and think that freestanding wasm with custom integrations is the more likely future.
The promise of wasi components has not been fulfilled. The market wants to hotload and link artifacts dynamically. The wasi project requires insider wizardry to use it that way: the offering has been statically linking components before you ship. Defeating 99% of the use cases.
I do not like that this has been worked on in the shadows.
There is an issue open for instantiating modules at runtime: https://github.com/WebAssembly/component-model/issues/423
I don't think it's fair to say this work has happened in the shadows. I work on CNCF wasmCloud, and I know how hard we try to make this content available.
- Many standing meetings organized around SIGs, all on the public community calendar: https://calendar.google.com/calendar/u/0/newembed?src=events...
- A dedicated Zulip: https://bytecodealliance.zulipchat.com/
- Conferences organized around exactly these topics: Wasm Day, WasmCon, Wasm I/O, and the Bytecode Alliance Plumbers Summit
- CNCF projects: wasmCloud, Spin
- Blogs, many with recordings, summaries, and transcripts: https://bytecodealliance.org/articles/the-road-to-component-..., https://wasmcloud.com/community/, https://spinframework.dev/blog/index
If you want the architectural direction straight from the source, Luke Wagner's keynotes are the best place to start:
- "What is a Component (and Why)?" (WasmCon 2023): https://www.youtube.com/watch?v=tAACYA1Mwv4
- "The Path to Components": https://www.youtube.com/watch?v=phodPLY8zNE
- "Towards a Component Model 1.0" (Wasm I/O 2026): https://www.youtube.com/watch?v=qq0Auw01tH8
I mean this, though - what else would you like to see to try and make the content and process more accessible? Are there communities that are doing this really well that we could use for inspiration?
> - "What is a Component (and Why)?" (WasmCon 2023): https://www.youtube.com/watch?v=tAACYA1Mwv4
At 18:00 the speaker states something like "It should not be Systems Interface but Standard Interfaces" which honestly sounds like a different project. As an implementer or even as just a user in general, can it be trusted that tomorrow it isn't something completely different? Seems like an odd standard to follow.
(EDIT and aside: Rereading this it reads more dismissive than I meant it. So if this isn't clear: I want WASI to succeed. I think having a widely used system interface is great, but I think many know standards that suffered from scope creep. And while big successful standards for better or for worse at least have a chance of surviving this, WASI as the 0.3 indicates is in its infancy. So I worry about it turning out bad, leading to people abandoning the idea altogether or the standard losing sight of its initial goal. So while this is criticism the only reason I bother to write it in first place is because I badly want it to succeed. I worry that if WASI tries to do too much at once - and I totally understand wanting to do that - it makes it less likely to be successfully implemented and thereby less likely to succeed as a standard.)
The speaker is right. Why should "system" interfaces and interfaces from other components ever be fundamentally different?
It's version 0.3...
Wrong direction. WASI should be simple and stable. Initially, it was revolving around a simple Unix-like API model and it was close to perfect. Now, there is an opinionated component model which is an unneeded overcomplication that should have never been considered as part of WebAssembly spec IMHO.
A real component model is a separate development and cannot be blindly tied to a particular ecosystem. Otherwise, its main purpose of providing easy interoperability between different ecosystems is totally lost.
I do not know why WebAssembly committee thinks that shoving-in CORBA-like monstrosity is even an acceptable idea. Let's keep WebAssembly lean and fast! Anything extra can (and should) be implemented by other technologies.
The component model is what unlocks relatively type-safe interop between modules written in different languages. Given that Wasm is a runtime target for many languages, this is an entirely appropriate and useful goal.
If you have a host system where you want to expose APIs in an language-agnostic way, IDLs are the best way to do that.
You're also conflating the core WebAssembly work with the WASI work. There is some overlap in people, but WASI is developed separately.
Why was the component model not expressed in LISP syntax like the way WAT is ? Why have yet another custom IDL language with bespoke parsing rules ?
There is a wat (s expression) syntax for the component model. The problem with the wat syntax for both Wasm and the component model is they’re a reflection of a binary format, and therefore are terrible for writing by hand. They’re designed to be written by tools, and the text format is just to help you understand the binary format.
I’ve written Wasm and component model wat extensively over the last decade to develop tests for Wasmtime, and even for an expert it’s a bad experience.
Wit syntax is easy to read and write by hand. There are high quality parsers that can transform it to and from the binary or wat format as needed, and code generators for a wide range of languages. It’s a way, way better experience in every way to deal with wit compared to the wat format.
The present component model is "simple and stable". It is presently providing "interoperability between different ecosystems" and has been for years. It has basically nothing in common with CORBA. All the major problems with the Unix design they ran into that caused them to switch to a component model haven't vanished; the component model is still the best way of solving WASM's major complications that traditional C-based designs don't have. C-based designs, in general, are not better just because they came first; if you were designing systems programming from scratch, you'd want something like WIT (proof: Microsoft has done this twice now).
AIUI, the underlying motivation for the WASM component model is the same as for the early interface types proposal, which has been a planned part of WASM since the very beginning - namely to allow modules written in high-level languages to expose "native" interfaces, without requiring a completely bespoke translation into WASM's lower level facilities. That's a sensible goal, even if achieving this may ultimately involve something that's at least loosely reminiscent of CORBA.
i don't think people calling it CORBA-like are doing it in good faith, but regardless, no we should not do unix apis everywhere for the rest of time please
what would you have it look like?
I agree. This is saddening. It seems to often happen in "standard first" scenarios for some reason. I was very happy when CloudABI and POSIX were picked as prior art inspiration.
Now it feels like it moved from "what would we need to get things done and achieve our goals?" to "what could be done and which goals could we achieve?"
Maybe I am missing something, but are the recent changes something that people requested?
Yes, you missed people asking for years: away to do interop between languages in WASM, a way to interact with browser APIs without JavaScript from WASM.
Component model enable both using one thing.
Fair enough. Isn't that another topic more tied to WASM compare to what initially claimed to be a "System Interface" and not a language interface or a browser interface?
I disagree. We shouldn't just be copying Unix until the end of time.
I think there is a difference between "just copying" and "building upon understood systems and standards".
Also to be fair "just copying" works really really well, especially for standards. The primary goal of standardization is not to invent something new, but to have a target that isn't constantly moving.
If you want to build something new and better do that, and if you are ready to build a standard based of it which is very valid. You can also build them together, and CloudABI which they mention as inspiration in their readme for example did it that way. All valid paths.
But you want to start out simple and something common so that people that make use of the standard have an easy time to implement it. After all having more than one implementation is why you need a standard. Otherwise it's maybe a specification, which again, fair enough.
I can stand behind not copying Unix until the end of time, but "Unix" is a common target that people know how to implement and use. And while not even the authors of Unix claim it's great or even good it is something that people already implement (often enough even when not targeting anything unixy at all) so if your goal is to create a standard that those people can target then abandoning that does seem like a wrong move.
less copying and more keeping in the spirit of, as it has clearly shown it is a model that is built to last
That's like saying "the US Constitution has clearly shown it's a model that is built to last"
Sometimes bad designs stick around due to pure inertia
Even if something lasts due to pure inertia it lasts. And something that lasts is pretty nice if you want a standard to last, or be implemented. The standard usually isn't the thing that you use to proof you can do something better, by being different. Because then everyone will have a harder time adapting it. People implement interfaces they dislike.
Since this is related to Webassembly, Browsers, the Web. The web has a lot of historically baggage, that one might have to work around at times, sometimes more sometimes less. There are good bits and not so good bits and in the end a lot of the time more modern web applications (whether you think they are good or bad) as well as web browsers jump through hoops to do things. For many applications there would be better protocols. But it became the dominant standard, a standard that is actually being used a lot and that is why it has become a success story. It wasn't a hundred times better than everything else. It simply was something that people managed to implement successfully and something where they were willing to deal with shortcomings, because there are great benefits in implementing the same standard as everyone else.
Don't know much about the US constitution, but it seems that it was largely good enough to make people work together that otherwise might have ended up fighting each other. That's what you'd get if everyone had a different idea about what a good constitution is. Maybe things are unclear, and maybe there are uproars because of things, but it doesn't even get to that if people don't agree on a standard or a constitution in first place.
And while over the years I often imagined how great it would be if everyone just used that better standard that has been there for a long time and nobody uses and is completely forgotten, if it ever had any popularity, then everything would be so much better and greater and I wouldn't have to do that senseless thing I am doing now. But if that standard doesn't allow for people to agree with it by implementing it it's essentially worthless (outside of maybe "prior art" consideration).
And like it or not we currently live in a world where designs persist due to pure inertia. But we know that obviously people are willing to implement these which means when a standard comes along that is similar to what already is there then having many people adapting it is realistic. Otherwise it's that super interesting university project that never makes it into anything in the real world.
Is there some Zig code demonstrating how to use all the changes in a Zig program that compiles to WASI 0.3.0?
If you have used WASI in the past, can you mention your use case? Very curious if you found it to give you an edge compared to other sandboxing like containers or VMs.
WASI is the best format for code submitted by users, entirely untrusted, which is in principle of any complexity but expected to be pretty simple. It works on any platform, in any environment, with extreme and direct control over its access to every resource and its ability to execute at all. Wasmtime's "fuel" feature is not something you can do with containers, and if you can do it with VMs then I don't know about it, but VMs are behemoths for the task of executing a simple function that would in an alternate universe be CEL.
I tinkered with https://extism.org and basically the use case is that they suggest, namely you can extend software in another programming language but without having to setup a container or VMs on the client. They "just" run the code in the browser and it can be JavaScript, sure, but can also be Python, Go, whatever.
It's quite specific though as I'm working on support programming in the browser.
If you are not deep into letting a very specific kind of user extend, it's probably overkill.
Even then it's a very VERY niche thing because it has to be simultaneously :
- someone who is opinionated about a programming language (either because they know too much, i.e. expert, or not enough, i.e beginner)
- is dedicated enough to want to try to build something on top of an existing system
- does not want to bother with solutions you mentioned
We evaluated Extism and concluded that it did basically nothing that WASI and the component model didn't already do out of the box. Was your experience different?
In-process sandboxed llm-generated code execution. Considerably lighter weight, faster to boot (assuming pre-compilation) than Docker or spinning up micro-VMs.
I'm using it for a secure, language agnostic workflow orchestrator. Components have very finely-grained and controller permissions and access to data. They don't even get clocks by default (to mitigate against Spectre-style attacks) and credentials and tainted data are sequestered.
Extending my Rust binary with a marketplace of WASM-based extensions like VSCode
The best usage example of WASI I know of is the Zig compiler: https://ziglang.org/news/goodbye-cpp/
Edge rural farm systems
extending software with a plugin system
If you don't want to download the .tar.gz I think you can browse the content for this release (.wit interface files) here on GitHub: https://github.com/WebAssembly/WASI/tree/v0.3.0/proposals
Will WebAssembly ever achieve a real breakthrough? It's been almost 10 years since it came around. HTML, CSS and JavaScript were a breakthrough back in the days. WebAssembly still is not right now; only very few folks or companies use it.
I think its killer use case is actually embedded in non-web places. Tree Sitter parsers require arbitrary programs to be able to parse arbitrary languages. WebAssembly is a natural way to achieve that: write your parser in any language, compile to WebAssembly, use that result in any supported editor. You get sandboxed execution and arbitrary compute.
It has to compete with more domain-adapted use cases though. Does WASM make more sense than eBPF for packet filtering? It doesn't seem to make more sense than JavaScript for making websites. Maybe it makes more sense for deploying edge services (which IIUC is the main use case for WASI).
Plugin architectures are a niche where WASM really shines. Before WASM most plugins were either high performance (loading dynamic libraries) or sandboxed and safe for untrusted plugins (LUA etc). WASM allows you to have your cake and eat it to. You pay with a bit of complexity, but it's in a great and somewhat unique place in the tradeoff space
I think I've seen you comment this on every recent WASM post, and I'm really wondering what you think breakthrough success looks like for a low-level technology like WASM?
Do you expect everyone to hand-code their websites in WASM? Do you expect every webapp be cross-compiled to WASM?
From where I'm standing, WASM is extremely successful in its specific niches: in enabling islands of high-performance in otherwise web-based software, and in sandboxing plugins to native apps/servers.
It's already a breakthrough in my opinion.
Many things are possible that weren't possible before. For example, I was able to compile the Dart VM (the compiler + analyzer + VM) to wasm and run it on the web: https://github.com/modulovalue/dart-live it supports hot reload and many other cool features. It runs essentially everywhere and it's a very bare proof of concept for a fully integrated programming development system.
The problem is that things just take time if you have to coordinate across a bunch of languages and teams while trying to make everyone happy.
To give you a sense of what else is coming: the wasm ecosystem is moving towards supporting a component model. Eventually you'll be able to import any piece of code from any programming language that supports it. Wasm interface types will make that possible.
> I was able to compile the Dart VM (the compiler + analyzer + VM) to wasm and run it on the web
Is this really a representative use-case of WASM/WASI? Would'n it be much better to compile Dart to WASM (the Dart SDK even supports "dart compile wasm")?
this is a confusing question; why would it be much better to e.g. compile a C program for x86 linux musl but not the C compiler?
It's a silent technology, but I'd argue it has broken through in that most of us already use it daily without knowing. Figma, Google Sheets, Disney+, Prime Video, and much more all have WebAssembly somewhere in their stack.
WebAssembly is used in all sorts of ways.
It's used heavily by major web apps like Figma, it's used to run non-Javascript languages on Cloudflare Workers, many compute-heavy web libraries rely on Wasm modules, many web games rely on Wasm, it's used for safe plugins in some native apps like Microsoft Flight Simulator, amongst other use cases.
It has, but its usually just an optimization, so goes unnoticed
WebAssembly doesn't beat JavaScript in performance, and that is embarrassing.
That's not accurate. I Googled for a recent performance benchmark and found this which indicates Wasm offers a notable performance gain: https://medium.com/@hashbyt/webassembly-vs-javascript-perfor...
My task in question was a number crunching task, basically doing multiply-and-add for 336-bit integers. I wrote a JS version, and a C version compiled into WASM by using Zig. You'd think that WebAssembly would trounce JS here, but it actually didn't.
The JS code had been written carefully to avoid allocations, and also avoiding the built-in JavaScript BigInt. I rolled my own BigInt instead using an array of numbers. Each number, despite being a double, was basically a 48-bit integer. Long multiplication requires splitting a 48-bit integer into two 24-bit integers so an intermediate multiplication result will fit in 48 bits.
The C version used 32x32=64-bit integer math. (Would have been nice if WASM had supported 64x64=128-bit multiplication)
Even with the overhead of using doubles instead of integers, the JavaScript and C versions ran at nearly the same speed. I think the C version was slightly faster, but not significantly. The C version took a lot longer to load, as it had to instantiate a Webassembly object, and had to run glue code to copy things in and out of Webassembly memory.
it is faster, but there is unacceptable loss when passing data to/from js, definitely an area needing improvement (or having to do it less)
https://hacks.mozilla.org/2026/02/making-webassembly-a-first...
Just allowing more than one arraybuffer could go a long way to help with performance. One array buffer for the wasm memory space, then an arraybuffer for each input or output argument.
WASI stands for WebAssembly System Interface.
It has little to do with the webassembly in the browser.
I use it to extend a native application, for example. No browser in sight at all.
I mean, it’s another tool. It doesn’t really make an entirely new kind of web app possible, but it’s useful for some specific compute-heavy tasks (with limitations like JS<->WASM being slow). It’s also useful for running not-JS in the browser; I’m building a lighting console with a web UI distributed over multiple devices, and being able to use the exact same structs/representation and algorithms on server and client is pretty neat. It’s like Node, but in reverse! But none of this is cause for paradigm shift, so I don’t think seeing a ”breakthrough” really is relevant.
You said the exact same thing a couple days ago. You don't know what you don't know.
WebAssembly has been a great success thanks to its excellent initial design.
for me its undebuggability.
-"hey, look at our C Rust FORTRAN to WASM translator, blahblah"
-"uhm, cool, how do I debug it?"
-"yeah...about that...you cant!"
Why can’t you?
This! The only way to get to a stable system at least with c/c++ source, where you can hunt bugs, is to have a fairly large unit test coverage. When something fails - add that as test case; run ctest - pray that this is discoverable with tests.
So wasm is a really strange compilation target for systems programming languages.
I mean there _are_ ways to debug it in a browser but they sort of suck.
I'm building a game where you learn to program golang or python and it all runs in webassembly, this way any student chromebook can just pick up and go.
That feels pretty revolutionary, no need to setup your local system to get core concepts.
Even have plans to use postgres in WASM (pglite), and I know a few real time apps use sqlite in WASM.