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Modern Web Guidance

An open-source skill collection from the Chrome, Edge, Firefox, and MDN teams, giving coding agents 203 modern web guides across 250 platform features plus a Manifest V3 Chrome extensions skill.

13.2k stars Updated Nov 10, 2026 Apache-2.0 2 skills

The roster

New

Build and Publish Chrome Extensions

GoogleChrome

Create or fix Manifest V3 Chrome extensions without common API bugs, and generate CHROMEWEBSTORE.md with store copy, permission justifications, privacy disclosures, and launch checks.

modern-web-guidance/chrome-extensions 13.2k
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modern-web-guidance

GoogleChrome

modern-web-guidance/modern-web-guidance 13.2k

What it does

Modern Web Guidance is an open-source collection of coding-agent skills stewarded by the Google Chrome, Microsoft Edge, Mozilla Firefox, and MDN teams. It steers agents away from outdated training-data patterns and toward current browser APIs, accessibility rules, and Baseline compatibility fallbacks.

The repository includes two skill packs: modern-web-guidance, which searches 203 developer use-case guides spanning 250 CSS, HTML, DOM, and JavaScript features via an offline embedding and BM25 CLI, and chrome-extensions for building and publishing Manifest V3 extensions. It installs via npx, Vercel's Skills CLI, or GitHub CLI, and ships plugins for Claude Code, OpenAI Codex, Google Antigravity, GitHub Copilot CLI, Grok Build CLI, and Kimi Code.

Guides are pruned for token efficiency and calibrated against Playwright evaluations on real web apps, lifting agent pass rates by 27 to 36 percentage points in published runs. You can gate experimental Origin Trial or single-engine features in .mwgrc, and run legacy-scan to spot outdated patterns in existing codebases.

When to use it

  • Your agent writes bloated JS for native CSS and HTML jobs

    Give it 203 curated guides covering 250 modern CSS, DOM, form, security, and View Transition features with lightweight fallbacks.

  • You want to modernize legacy frontend code across a repo

    Run the built-in legacy-scan command to flag outdated patterns in your codebase and retrieve tested replacements guide by guide.

  • You're building or publishing a Manifest V3 Chrome extension

    Install the companion chrome-extensions skill pack for 20 mandatory Manifest V3 rules, 19 API guides, and Chrome Web Store launch docs.

Common questions

How do I install Modern Web Guidance?

Run npx modern-web-guidance@latest install for the guided wizard, or add --choose to pick individual skill packs. You can also install via npx skills add GoogleChrome/modern-web-guidance, gh skill install, or native plugins for Claude Code, Codex, Antigravity, Copilot CLI, Grok, and Kimi.

Which coding agents does it work with?

Modern Web Guidance supports Claude Code, OpenAI Codex, Google Antigravity, GitHub Copilot CLI, Grok Build CLI, and Kimi Code directly, as well as any agent compatible with the Vercel Skills CLI or GitHub CLI skill installer.

Is it free and does the CLI work offline?

Yes. Software code is Apache-2.0 licensed and guide docs are CC-BY 4.0. Search and retrieval run locally with zero external API keys using an embedded model and BM25 index, though npx fetches the package once and anonymous usage telemetry is enabled unless DISABLE_TELEMETRY=1 is set.

How does it handle experimental browser APIs?

Guides for Origin Trial APIs and newly shipped single-engine features stay discoverable in search results but are blocked on retrieve by default. You can opt in per project or user via .mwgrc so agents never adopt unstable APIs without consent.