Thomas Steiner

Thomas Steiner

@tomayac.com

Developer Relations Engineer at Google, focused on the Web, WebAssembly, and Project Fugu 🐡. Dad-of-3.

3.3K followers 238 following237 posts

Thomas Steiner reposted

Joaquín Sánchez

@userquin.bsky.social

After a few months of hard work, we're happy to announce the initial @unplugin-pwa v0.0.2 packages! We completely rearchitected the core. Just look at the diet: we went from 321 total dependencies down to just 22, cutting the install size from 43.3MB to 4.1MB. Leaner, faster, and bundler-agnostic.

On my way to #w3cTPAC with a Chromium build with the entirety of the #CrossOriginStorage API:

github.comRelease Chromium with Cross-Origin Storage (macOS arm64, 2026-10-20) · tomayac/ChromiumUnofficial macOS arm64 developer build of Chromium 157.0.8092.0 with the Cross-Origin Storage API, its declarative integrations, its DevTools integration, its settings page, an extension API, and a...

* `navigator.crossOriginStorage.getFileHandle()` * `crossoriginstorage` attribute for HTML * `cross-origin-storage()` URL request modifier for CSS * `crossOriginStorage` import attribute for JS

github.comRelease Chromium with Cross-Origin Storage (macOS arm64, 2026-10-20) · tomayac/ChromiumUnofficial macOS arm64 developer build of Chromium 157.0.8092.0 with the Cross-Origin Storage API, its declarative integrations, its DevTools integration, its settings page, an extension API, and a...

* `crossOriginStorage` `RequestInit` option for fetch() * Strawman `browser.crossOriginStorage.*` for extensions * `chrome://settings/content/crossOriginStorage` Settings * DevTools support Try it: github.com/tomayac/Chro...!

github.comRelease Chromium with Cross-Origin Storage (macOS arm64, 2026-10-20) · tomayac/ChromiumUnofficial macOS arm64 developer build of Chromium 157.0.8092.0 with the Cross-Origin Storage API, its declarative integrations, its DevTools integration, its settings page, an extension API, and a...

Thomas Steiner reposted

Getting my TOTP data out of Twilio's Authy app thanks to the GDPR: blog.tomayac.com/2026/10/17/g.... New blog post in which I document how I used the sledgehammer 🔨 that is #GDPR to get my #TOTP #2FA 🔐 data out of #Authy and built myself a TOTP Vault PWA.

blog.tomayac.comGetting my TOTP data out of Twilio's Authy app thanks to the GDPRThe personal blog of Thomas Steiner

Getting my TOTP data out of Twilio's Authy app thanks to the GDPR: blog.tomayac.com/2026/10/17/g.... New blog post in which I document how I used the sledgehammer 🔨 that is #GDPR to get my #TOTP #2FA 🔐 data out of #Authy and built myself a TOTP Vault PWA.

blog.tomayac.comGetting my TOTP data out of Twilio's Authy app thanks to the GDPRThe personal blog of Thomas Steiner

Thomas Steiner reposted

Refueling an EV be like: blog.tomayac.com/2026/10/08/r.... New blog post in which I describe a worst case (but not too far from the average) public charging experience for people who never drove an electric vehicle. 🚗🪫 Despite the horrors, I'd never go back to another car. 🔋☀️ #EV #EVdriving #Solar

blog.tomayac.comRefueling an EV be likeThe personal blog of Thomas Steiner

Refueling an EV be like: blog.tomayac.com/2026/10/08/r.... New blog post in which I describe a worst case (but not too far from the average) public charging experience for people who never drove an electric vehicle. 🚗🪫 Despite the horrors, I'd never go back to another car. 🔋☀️ #EV #EVdriving #Solar

blog.tomayac.comRefueling an EV be likeThe personal blog of Thomas Steiner

📢 #CrossOriginStorage API update: we have renamed `navigator.crossOriginStorage.requestFileHandle()` to `getFileHandle()` for better symmetry with the OPFS API, so it's easier coming from OPFS's `getFileHandle()` (developer.mozilla.org/en-US/docs/W...). OPFS's `name` is COS's `hash`.

developer.mozilla.orgFileSystemDirectoryHandle: getFileHandle() method - Web APIs | MDNThe getFileHandle() method of the FileSystemDirectoryHandle interface returns a FileSystemFileHandle for a file with the specified name, within the directory the method is called.

It's early days for the #CrossOriginStorage API, but because it works perfectly as a progressively enhancement, why not teach your agents already how to use it? Modern Web Guidance now has, well, guidance for using the COS API. ⤵️

Rick Viscomi@rviscomi.dev

v0.0.191 of Modern Web Guidance is out and it's a big one! *16* new guides covering: web components by @castastrophe.bsky.social Cross-Origin Storage by @tomayac.com security by @rowan.fyi UI and PWA by @jamessw.com and @sturobson.com Wasm by @sbc100.bsky.social github.com/GoogleChrome...

Friendly reminder that there's a way to go on-the-record with your project's or company's #CrossOriginStorage API use case and express support. This can be helpful when discussing with other vendors. 👉 Current supporters: github.com/WICG/cross-o... 👉 Add yours: github.com/WICG/cross-o...

github.comIssues · WICG/cross-origin-storageCross-Origin Storage (COS), a content-addressable browser cache that shares files across origins by hash, with k-anonymity-based availability gating to prevent cross-site tracking - Issues · WICG/c...

You can additionally also comment on the #CrossOriginStorage API feature request bugs. (Please make your comment meaningful, don't just write "me too" or "+1".) 🧭 WebKit: bugs.webkit.org/show_bug.cgi... 🦊 Mozilla: bugzilla.mozilla.org/show_bug.cgi...

bugs.webkit.org324017 – Support Cross-Origin Storage

Another #CrossOriginStorage API DevTools exploration: showing some metadata for resources on the Public Hash List (github.com/WICG/cross-o...), so the entries in the table are more than opaque hash strings.

You can now download the macOS binary with this feature (☝️) enabled from github.com/tomayac/Chro.... (Launch Chromium, open `about://flags`, search for Cross-Origin Storage, set it to Enabled, and restart when prompted.) #CrossOriginStorage

github.comgithub.com

Thomas Steiner reposted

I was on the @shoptalkshow.com with @chriscoyier.net and @davatron5000.bsky.social to chat about the #CrossOriginStorage API, see the quoted skeet ⤵️. If you bookmark just one link after the show, make it github.com/tomayac/awes....

github.comGitHub - tomayac/awesome-cross-origin-storage: A curated list of resources for the Cross-Origin Storage (COS) APIA curated list of resources for the Cross-Origin Storage (COS) API - tomayac/awesome-cross-origin-storage

shoptalkshow.com@shoptalkshow.com

732: Thomas Steiner on New Cross-Origin Storage APIs

shoptalkshow.com732: Thomas Steiner on New Cross-Origin Storage APIs

I was on the @shoptalkshow.com with @chriscoyier.net and @davatron5000.bsky.social to chat about the #CrossOriginStorage API, see the quoted skeet ⤵️. If you bookmark just one link after the show, make it github.com/tomayac/awes....

github.comGitHub - tomayac/awesome-cross-origin-storage: A curated list of resources for the Cross-Origin Storage (COS) APIA curated list of resources for the Cross-Origin Storage (COS) API - tomayac/awesome-cross-origin-storage

shoptalkshow.com@shoptalkshow.com

732: Thomas Steiner on New Cross-Origin Storage APIs

shoptalkshow.com732: Thomas Steiner on New Cross-Origin Storage APIs

Akaash Parthasarathy from the WebLLM team has filed WebKit and Mozilla feature request bugs asking for #CrossOriginStorage API support in Firefox and Safari: 🧭 bugs.webkit.org/show_bug.cgi... 🦊 bugzilla.mozilla.org/show_bug.cgi... (Chrome's implementation bug is crbug.com/547587764.)

bugs.webkit.org324017 – Support Cross-Origin Storage for reuse of WebLLM model artifacts across sites

🎧 I was a guest of @codepo8.bsky.social again for the @wearedevelopers.bsky.social podcast to talk about the #CrossOriginStorage API: www.wearedevelopers.com/videos/2162-.... Happy listening! (Find all related resources on the Awesome Cross-Origin Storage 😎 list: github.com/tomayac/awes...)

Thomas Steiner reposted

DevTools and browser Settings UI exploration for the #CrossOriginStorage API is coming along nicely. What would you expect to see in both DevTools and Settings? Let me know!

DevTools and browser Settings UI exploration for the #CrossOriginStorage API is coming along nicely. What would you expect to see in both DevTools and Settings? Let me know!

🤩 Fantastic article by @nucliweb.net on HTTP cache partitioning and the #CrossOriginStorage API: joanleon.dev/en/http-cach.... Try the embedded demos with the COS extension installed or in one of the experimental browser builds (see the Awesome Cross-Origin Storage list: github.com/tomayac/awes...).

joanleon.devHTTP cache partitioning: the same image, downloaded twice | Joan LeónA page with a cross-site iframe requests the same image from the iframe and from the parent. Chrome downloads it twice; Firefox and Safari, once. Why the cache key differs across the three engines, wh...

Thomas Steiner reposted

I have a new unofficial macOS Chromium build out for you to test with #CrossOriginStorage API support and full DevTools integration: goo.gle/cos-chromium. Remember to set the Cross-Origin-Storage flag in `chrome://flags/#cross-origin-storage` and find Cross-origin storage on the Application tab.

I have a new unofficial macOS Chromium build out for you to test with #CrossOriginStorage API support and full DevTools integration: goo.gle/cos-chromium. Remember to set the Cross-Origin-Storage flag in `chrome://flags/#cross-origin-storage` and find Cross-origin storage on the Application tab.

Early Chrome DevTools exploration for debugging the #CrossOriginStorage API. This shows global stats first and then per-origin stats, here inspecting Three.js. - (WIP) backend CL: chromium-review.googlesource.com/c/chromium/s... - (WIP) frontend CL: chromium-review.googlesource.com/c/devtools/d...

macOS users interested in #CrossOriginStorage: you can now run a test build with the API behind a flag 🚩: github.com/tomayac/Chro.... In `about://flags`, search for Cross-Origin Storage, set it to Enabled, restart when prompted. To un-quarantine the app, see github.com/tomayac/Chro....

github.comgithub.com

🤩 It's happening!!1! I just sent the "Intent to Prototype" email for the #CrossOriginStorage API: groups.google.com/a/chromium.o.... If you want to stay in the loop, star the ☂️ umbrella Chromium bug crbug.com/547587764 (and the subtask bugs: crbug.com/547587764/de...).

groups.google.comIntent to Prototype: Cross-Origin Storage

😎 Chromium (personal fork) passing all Web Platform Tests of the #CrossOriginStorage API. * WIP CL: chromium-review.googlesource.com/c/chromium/s... * Runnable binary: github.com/tomayac/Chro... (Linux x86_64)

Look, ma, that's WebKit 🧭 passing all Web Platform Tests for #CrossOriginStorage. And you can try it: github.com/tomayac/WebK... (personal fork)! That's now four prototype implementations of the API in four different browsers: github.com/tomayac/awes... (all of them with releases you can run).

For the first time you can try the #CrossOriginStorage API on a "real" browser—after the still in-development browsers [shells] Servo and Ladybird: I managed to implement the API in proper Firefox 🦊: github.com/tomayac/awes... (Note that all of those are personal experimental builds.)

github.comGitHub - tomayac/awesome-cross-origin-storage: A curated list of resources for the Cross-Origin Storage (COS) APIA curated list of resources for the Cross-Origin Storage (COS) API - tomayac/awesome-cross-origin-storage

More #CrossOriginStorage API updates: filed HTML issues (CSS already existed) toward better integration in the platform: * Add `crossoriginstorage` attribute to `<link>` and `<script>`: github.com/whatwg/html/... * Add `crossOriginStorage` JavaScript import attribute: github.com/whatwg/html/...

github.comAdd `crossoriginstorage` attribute to `<link>` and `<script>` · Issue #12770 · whatwg/htmlWhat problem are you trying to solve? <link> and <script> elements load resources declaratively, driven entirely by markup, before any page script needs to run. The Cross-Origin Storage (COS) API (...

The CSS #CrossOriginStorage issue is: * Proposal for a new `<request-url-modifier>` called `<cross-origin-storage>`: github.com/w3c/csswg-dr...

github.com[css-values-5] Proposal for a new `<request-url-modifier>` called `<cross-origin-storage>` · Issue #14056 · w3c/csswg-draftsBackground On the Chrome team, we're considering a new browser API and storage mechanism called Cross-Origin Storage (COS), which would allow for resources (like huge AI models but also large Web f...

See this progressively enhanced demo page for what these proposals would enable: web-ai-community.github.io/cross-origin...! (Try the demo without or with the #CrossOriginStorage extension installed: github.com/web-ai-commu...)

web-ai-community.github.ioCross-Origin Storage — progressive enhancement demo

If you want to experience Cross-Origin Storage (COS) in two real browsers, I managed to add full imperative COS API support (`navigator.crossOriginStorage`) to both @servo.org and Ladybird (personal prototypes): github.com/tomayac/awes.... #CrossOriginStorage

github.comGitHub - tomayac/awesome-cross-origin-storage: A curated list of resources for the Cross-Origin Storage (COS) APIA curated list of resources for the Cross-Origin Storage (COS) API - tomayac/awesome-cross-origin-storage

I'm keeping track of the learnings in the implementation notes (github.com/WICG/cross-o...), which hopefully will be useful for other vendors. #CrossOriginStorage

github.comgithub.com

You can find Web Platform Tests in github.com/web-platform....

github.comAdd tests for Cross-Origin Storage API by tomayac · Pull Request #61811 · web-platform-tests/wptSpec draft: https://wicg.github.io/cross-origin-storage/ Explainer: https://github.com/WICG/cross-origin-storage/blob/main/README.md This PR covers both the imperative API (navigator.crossOriginSt...

Super happy to announce that I'll be presenting about the #CrossOriginStorage API at #JSNationUS 2026: gitnation.com/badges/jsnat.... Click this link to sign up for partial free streaming access! Here's the talk's abstract: gitnation.com/contents/cro....

gitnation.comCheck out my badge & claim your free JSNation US 2026 remote ticket!Join 5k engineers worldwide at JSNation US 2026 and meet 50+ top speakers at November 16 - 19, 2026

Hope to see some of you at @jsnation.gitnation.org, physically or on streaming! 👋

I've now filed (or commented on existing) standards position requests from other browser vendors (WebKit & Mozilla) and the W3C TAG for the #CrossOriginStorage API: * Mozilla: github.com/mozilla/stan... * WebKit: github.com/WebKit/stand... 🆕 * W3C TAG: github.com/w3ctag/desig... 🆕

github.comCross-Origin Storage (COS) · Issue #1427 · mozilla/standards-positionsSpecification title Cross-Origin Storage (COS) Specification or proposal URL (if available) No response Explainer URL (if available) https://github.com/WICG/cross-origin-storage/ Proposal author(s)...

If you're interested in the Cross-Origin Storage API, I just created a new Bluesky feed, check it out and pin it if you like it: bsky.app/profile/did:... #CrossOriginStorage

I was once again a guest on the German-speaking 🇩🇪 @workingdraft.de podcast 🎙️ to talk about the Cross-Origin Storage API: workingdraft.de/723/. thoroughly enjoyed chatting about this exciting API proposal with @schepp.dev and @sirpepe.bsky.social. Track #CrossOriginStorage for more.

workingdraft.deRevision 723: Cross-Origin Storage API – Caching über Origins hinweg, mit Thomas Steiner | Working DraftWir sprechen mit Thomas Steiner (Mastodon, Bluesky, LinkedIn) von Google über einen neuen Vorschlag für die Webplattform: die Cross-Origin-Storage API. Tom war bereits mehrfach bei uns zu Gast, zuletz...

Thomas Steiner reposted

@web-standards.dev

Cross-Origin Storage API: stop downloading twice. @morello.dev explains a proposed standard that stores large files by their SHA-256 hash, so origins share one device cache instead of downloading duplicates. #performance #browser morello.dev/blog/cro...

Thomas Steiner reposted

Nice to see this being worked on 🤩 You can already use `<input type="checkbox" switch>` today BTW, thanks to this polyfill by my colleague @tomayac.com: github.com/tomayac/inpu...

github.comGitHub - tomayac/input-switch-polyfill: A polyfill for <input type="checkbox" switch>A polyfill for <input type="checkbox" switch>. Contribute to tomayac/input-switch-polyfill development by creating an account on GitHub.

IntentToShip@intenttoship.dev

Blink: Intent to Prototype: <input type="checkbox" switch>

groups.google.comBlink: Intent to Prototype: <input type="checkbox" switch>Blink: Intent to Prototype: <input type="checkbox" switch>

Cross-Origin Storage API: Stop Downloading Twice: dev.to/morellodev/c.... A great overview of our proposal for the #CrossOriginStorage API by Dennis Morello. 👏

dev.toCross-Origin Storage API: Stop Downloading TwiceThe Cross-Origin Storage API lets sites share one cached copy of a file (a JS library, font, or AI model) across origins by SHA-256 hash. Here's how it works.

Dennis is @morello.dev.

Thomas Steiner reposted

Joaquín Sánchez

@userquin.bsky.social

Integrating Vite PWA Inspector with @vite.dev devtools, the inspector can run also as a seperated middleware (ala vite-plugin-inspect or UnoCSS inspector). @tomayac.com #PWA

👀 Look, ma! The Cross-Origin Storage extension running on Firefox! If you dare, install it via `about:debugging` from github.com/web-ai-commu.... Else, just wait for it to be approved on the Firefox Add-on Store. More background on #CrossOriginStorage: github.com/WICG/cross-o....

The Cross-Origin Storage extension was now approved for the Firefox Add-on Store: addons.mozilla.org/en-US/firefo.... 🦊 🧩 #CrossOriginStorage

addons.mozilla.orgCross-Origin Storage – Get this Extension for 🦊 Firefox (en-US)Download Cross-Origin Storage for Firefox. Implements the proposed Cross-Origin Storage API, letting sites share files with your consent for a faster and more efficient web.

Started an Awesome Cross-Origin Storage list: github.com/tomayac/awes... . Transformers.js, WebLLM, wllama, Flutter, Emscripten, Nuxt and Vite plugins, and a bunch of demos… #Awesome #CrossOriginStorage

github.comGitHub - tomayac/awesome-cross-origin-storage: A curated list of resources for the Cross-Origin Storage (COS) APIA curated list of resources for the Cross-Origin Storage (COS) API - tomayac/awesome-cross-origin-storage

Really great questions and comments on @danielroe.dev's posts on Nuxt's experiments with the Cross-Origin Storage API (github.com/WICG/cross-o...): 🐘 Mastodon: mastodon.roe.dev/@daniel/1168... 🦋 Bluesky: bsky.app/profile/dani... 💼 LinkedIn: www.linkedin.com/posts/daniel...

github.comGitHub - WICG/cross-origin-storage: Explainer for the Cross-Origin Storage (COS) APIExplainer for the Cross-Origin Storage (COS) API. Contribute to WICG/cross-origin-storage development by creating an account on GitHub.

daniel r(ooooooh) in nyc 🇺🇸@danielroe.dev

wouldn't it be nice if sites could share a cache of common js? ... stuff like react, or vue or svelte? 👉 there's an early stage proposal for cross-origin storage which enables exactly this. there are challenges but I think it's very interesting indeed

github.comGitHub - WICG/cross-origin-storage: Explainer for the Cross-Origin Storage (COS) APIExplainer for the Cross-Origin Storage (COS) API. Contribute to WICG/cross-origin-storage development by creating an account on GitHub.