🆕 Introducing the MDN MCP server!

Bring MDN's docs and browser compatibility data straight into your AI agent or IDE for accurate, up-to-date answers about the web platform.

• Works with VS Code, Zed, Cursor, Claude Code, Codex CLI, Claude Desktop, and more
• No more outdated guesses from training data
• Reliable Baseline and browser support info

Currently experimental. We'd love your feedback.

Learn more 👇
https://developer.mozilla.org/en-US/blog/introducing-mdn-mcp-server/

Ever wish HTTP status codes were easier to remember? 🖼️

Check out this MDN cheatsheet that pairs each status code with an emoji to help you visualize what each one means, from 200 OK ✅ to 418 I’m a teapot 🫖

Check it out 👇

🦊 Firefox 150: web extensions can now use the Web Authentication API.

Extensions can create and retrieve WebAuthn credentials for any domain covered by their host permissions.

Read Now 👇
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

🦊 Firefox 150: <img sizes="auto"> is now supported.

Lazy-loaded images use their calculated layout size to select from srcset — no more duplicating media queries in HTML.

Read Now 👇
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

🦊 New in Firefox 150: the revert-rule CSS keyword.

Make a property behave as if the current rule didn't exist, letting a value from another matching rule take effect instead.

Read Now 👇
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

🦊 Firefox 150: light-dark() now accepts image values — not just colors.

Use it with images and gradients to adapt visuals based on color scheme.

background: light-dark(url(light.png), url(dark.png));

Read Now 👇
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

🦊 Firefox 150 ships ariaNotify() on Document and Element.

Queue text to be announced by a screen reader — a more ergonomic and reliable alternative to ARIA live regions.

Read Now 👇
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

🦊 Firefox 150: color-mix() now accepts more than two colors at once.

Mix any number of colors in a single declaration — no more nesting multiple calls.

Read Now 👇
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/150

Have you heard of CSS Subgrid? 🤔

A grid item can now pass its parent's grid lines to children, so nested elements align perfectly with the outer layout.

No more hacky workarounds for aligned nested grids.

Learn more 👇
https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_grid_layout/Subgrid

🆕 The URL Pattern API is Newly Available!

Use it to match and extract parts of URLs, no need to reinvent routing logic. Supports literals, wildcards, named groups, and even regex constraints.

Learn how it works 👇
https://developer.mozilla.org/en-US/docs/Web/API/URL_Pattern_API