What’s New in Web – Insights from TPAC 2026

Christian is a member of the World Wide Web’s architecture board, the Technical Architecture Group (TAG) of W3C. Join Christian, just back from the W3C's annual Technical Plenary and Advisory Committee (TPAC) week in Dublin, where all W3C working groups such as CSS, WebApps, and Web Machine Learning come together. In his session, you'll gain insights into the latest discussions among standards bodies, browser vendors, and web developers. And you have the opportunity to report your wishes back to the Web’s architecture board. Don't miss this opportunity to stay updated on the forefront of web technologies.

Transcript

1. What’s New in Web? Insights from TPAC 2026 Christian Liebel @christianliebel Consultant
2. What’s New in Web? Insights from TPAC 2026 Christian Liebel Hello, it’s me. W3C TAG Web Application Manifest Editor WebApps & WebML christian.liebel @thinktecture.com
3. What’s New in Web? Insights from TPAC 2026 TAG Technical Architecture Group
4. What’s New in Web? Insights from TPAC 2026 TAG
5. What’s New in Web? Insights from TPAC 2026 TAG Next TAG F2F: 16–19 March 2027 Karlsruhe Get ready for a developer meetup! Community partners wanted!
6. What’s New in Web? Insights from TPAC 2026 TPAC Technical Plenary and Advisory Committee
7. What’s New in Web? Insights from TPAC 2026 TPAC
8. What’s New in Web? Insights from TPAC 2026 TPAC Schedule One of five days
9. What’s New in Web? Insights from TPAC 2026 Age Assurance Trilemma Martin Thomson: Think of the Children
10. What’s New in Web? Insights from TPAC 2026 Digital Credentials API https://developer.chrome.com/blog/digital-credentials-api-origin-trial
11. What’s New in Web? Insights from TPAC 2026 Digital Credentials API https://bmds.bund.de/aktuelles/pressemitteilungen/detail/d-you-deutschland-startet-digitale-identitaet-fuer-alle
12. What’s New in Web? Insights from TPAC 2026 Digital Credentials API https://www.w3.org/2001/tag/doc/prevent-credential-abuse/#harms
13. What’s New in Web? Insights from TPAC 2026 <agecheck> WebKit Proposal I am 16 or older! Browser User Service Platform Provider https://github.com/WebKit/explainers/tree/main/agecheck
14. What’s New in Web? Insights from TPAC 2026 HTTP Protocols http https httpq
15. What’s New in Web? Insights from TPAC 2026 HTTPQ Only a request! Tentative opinion: This should happen as a part of https! https://mailarchive.ietf.org/arch/browse/uri-review/?gbt=1&index=8h4GXD_Sdlkaz_grEHqjkSCdszw
16. What’s New in Web? Insights from TPAC 2026 Post-Quantum TLS Chromium Plan https://www.ietf.org/slides/slides-pqws-12-1340-chromium-00.pdf
17. What’s New in Web? Insights from TPAC 2026 Peripheral APIs Moved to WHATWG – Web Bluetooth – Web Serial – WebUSB – WebHID – WebNFC
18. What’s New in Web? Insights from TPAC 2026 Web Install TAG Finding
19. What’s New in Web? Insights from TPAC 2026 Element-Scoped View Transitions DEMO https://view-transitions.chrome.dev/my-patagonia-trip/
20. What’s New in Web? Insights from TPAC 2026 Web Haptics Imperative Declarative navigator .playHaptics("align", 0.8); button { haptic: click align 0.8; } https://github.com/WICG/web-haptics
21. What’s New in Web? Insights from TPAC 2026 CSS Types for Custom Properties CSS Custom Functions and Mixins Level 1 --angle: 45deg; @property --angle { syntax: "<angle>"; inherits: false; initial-value: 0deg; } @property --angle <angle>: 0deg; https://github.com/WICG/web-haptics @function --fluid(--min <length>, --max <length>) { @property --slope <length>: 0px; --slope: calc((var(--max) var(--min)) / 100); result: clamp(var(--min), var(--slope) * 1vw, var(-max)); }
22. What’s New in Web? Insights from TPAC 2026 CSS APIs now supported by two engines In Dev Preview in WebKit: – Device Posture API – Viewport Segments API https://share.google/zzX4CjvZVHke8rriG
23. What’s New in Web? Insights from TPAC 2026 Observables – Native implementation of Observables in browsers – Debate about Observable subscription semantics (cold-by-default vs. other approaches) – Discussed in WICG https://wicg.github.io/observable/ element .when('click') .filter((e) => e.target.matches('.foo')) .map((e) => ({ x: e.clientX, y: e.clientY })) .subscribe({ next: handleClickAtPoint });
24. What’s New in Web? Insights from TPAC 2026 Built-in AI – Initiative by Google Chrome – Exploratory APIs for local experiments and use case determination – Downloads AI models into Chrome/Edge (offline capable) – Models are shared across origins – Uses native APIs directly (full performance) Browser BIAI APIs Website HTML/JS AI Models Device https://developer.chrome.com/docs/ai/built-in
25. What’s New in Web? Insights from TPAC 2026 Built-in AI New Proposals – Semantic Embedder API vs. Vector Store API – Decision API DEMO
26. What’s New in Web? Insights from TPAC 2026 WebMCP – Allows websites to expose tools to the browser or external agents – Joint effort by Microsoft and Google https://github.com/webmachinelearning/webmcp
27. What’s New in Web? Insights from TPAC 2026 WebMCP Imperative DEMO https://googlechromelabs.github.io/webmcp-tools/demos/pizza-maker/
28. What’s New in Web? Insights from TPAC 2026 WebMCP API Imperative Declarative document.modelContext.registerTool({ "name": "start_game", "description": "Start a new game.", "inputSchema": {}, "execute": () => { // Do something }, }); <form id="reservationForm" toolname="book_table_le_petit_bistro" tooldescription=...> <input name="name" toolparamdescription="Customer's full name (min 2 chars)" /> </form>
29. What’s New in Web? Insights from TPAC 2026 WebMCP TPAC Updates – Origin Trials in Chromium extended – WebMCP Polyfill is official W3C OSS project – Per Mozilla’s request, WebMCP will be reframed as an external communication tool (“WebRPC”) – Imperative API should be done first before tackling declarative https://github.com/webmachinelearning/webmcp
30. What’s New in Web? Insights from TPAC 2026 Cross-Origin Storage https://github.com/wicg/cross-origin-storage
31. What’s New in Web? Insights from TPAC 2026 Priority of Constituencies User needs come before the needs of web page authors, which come before the needs of user agent implementors, which come before the needs of specification writers, which come before theoretical purity. https://www.w3.org/TR/design-principles/#priority-of-constituencies
32. Thank you for your kind attention! Christian Liebel @christianliebel christian.liebel@thinktecture.com