The GoogleChrome/modern-web-guidance repository reached a stable release on November 10, 2026, after nearly two hundred preview versions published since summer. Jointly maintained by the Chrome, Microsoft Edge, Mozilla Firefox, and MDN teams, the project gives coding agents structured access to web platform best practices and browser compatibility data, so they stop reproducing outdated code.
A Known Problem: Agents That Code Like It’s 2019
The language models behind coding agents are trained on data heavily weighted toward old code. The result: faced with a need the web platform can now handle natively, an agent tends to reach for a polyfill, a third-party library, or an outdated pattern instead. The project starts from a precise observation: a model can know an API exists without knowing how to use it correctly in production.
What Version 1.0 Covers
Modern Web Guidance claims coverage of 250 web platform features and 203 real-world use cases, organized by domain.
| Category | Example topics covered |
|---|---|
| CSS & Layout | Container queries, anchor positioning, View Transitions |
| HTML & DOM | Popover API, the native dialog element |
| JavaScript & APIs | scheduler.yield, Temporal, passkeys |
The repository, released under the Apache 2.0 license, already carries about 3,500 stars and 120 forks on GitHub.
Installation and Commands
The project installs through a dedicated CLI, which drops the skill files in place and can keep them updated:
# Interactive install
npx modern-web-guidance@latest install
# Search for a guide on a specific topic
npx modern-web-guidance search "view transitions"
# Scan an existing project for outdated patterns
npx modern-web-guidance legacy-scan ./src
Plugins are provided for several agents, including Claude, Codex, Cursor, and Gemini, echoing the approach already documented in the piece on editorial agents in production.
A Joint Initiative Across Browser Engines
The joint involvement of Chrome, Edge, Firefox, and MDN sets this project apart from the many extensions built for a single agent. It mirrors the standardization logic already seen around the Model Context Protocol: rather than letting every agent vendor build its own knowledge base, browser makers are pooling a single source, updated on the same cadence as their own compatibility data.
A coding agent can know that a web platform API exists without knowing how to use it correctly in production.
Modern Web Guidance does not replace human code review. The legacy-scan command flags outdated patterns, but deciding whether to replace them, and checking what the agent generates, remains the development team’s job.
The Takeaway
Modern Web Guidance reaches a stable release after several months of preview versions, jointly backed by the major browser engines. The tool installs with one command, covers 250 modern web features, and plugs into most existing coding agents. It fits into a broader trend of browser makers and AI tool vendors pooling best practices.
One detail stands out in this project: it is maintained by direct competitors in the browser market, brought together around a shared goal. On recent engagements, coding agents improve markedly as soon as they are given explicit context about modern APIs instead of guessing from training memory — a tool like this should quickly become as routine to install as a linter — Simon Janvier.
Further reading: the official repository on GitHub, GoogleChrome/modern-web-guidance.
