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Is W3C Validator API down?

Current status, daily uptime history and troubleshooting for the W3C Validator API (Development).

No, W3C Validator is up

W3C Validator answered our last daily check (Oct 24, 2026, 12:25 UTC) in 283 ms with HTTP 200.

Checking W3C Validator now…

Sending a request from our server.

W3C Validator API uptime history

30 days agoLatest check
Uptime
2 checks so far
Last check
Oct 24, 2026, 12:25 UTC
Response
283 ms · HTTP 200
Last up
Now

We check W3C Validator's listed URL (https://validator.w3.org/docs/api.html) once a day. History started when W3C Validator was first checked, so new entries show fewer than 30 days.

W3C Validator API not working for you?

  1. A 429 response means you're being rate-limited. Slow down, cache responses, and respect any Retry-After header.
  2. If calls fail only in the browser with a CORS error, W3C Validator may not allow cross-origin requests. Call it from your server instead.
  3. If it works from one network but not another, check firewalls, VPNs and regional blocks.
  4. Check the provider's documentation, status page or social accounts for planned maintenance or a changed endpoint.

Development APIs up at their last check

  1. 1Icanhazip logo

    Icanhazip API

    Online · 278 ms

    The family of icanhaz sites help you get more information about your network connection.

    • No API key needed
    • Fast: 278 ms response
    • Callable from the browser (CORS)
    • HTTPS
    No authHTTPSCORS
  2. 2Index Agentica logo

    Index Agentica API

    Online · 382 ms

    Agent-first directory of skills, MCP servers, tools, protocols and APIs as JSON, markdown, llms.txt.

    • No API key needed
    • Fast: 382 ms response
    • Callable from the browser (CORS)
    • HTTPS
    No authHTTPSCORS
  3. 3Open VSX logo

    Open VSX API

    Online · 270 ms

    Search and access VS Code extensions from the Open VSX registry.

    • No API key needed
    • Fast: 270 ms response
    • Callable from the browser (CORS)
    • HTTPS
    No authHTTPSCORS
  4. 4RubyGems logo

    RubyGems API

    Online · 360 ms

    Ruby gem metadata, versions, dependencies and search.

    • No API key needed
    • Fast: 360 ms response
    • Callable from the browser (CORS)
    • HTTPS
    No authHTTPSCORS
  5. 5Statically logo

    Statically API

    Online · 324 ms

    A free CDN for developers.

    • No API key needed
    • Fast: 324 ms response
    • Callable from the browser (CORS)
    • HTTPS
    No authHTTPSCORS

Compare all W3C Validator alternatives · APIs down right now

W3C Validator API status FAQ

Is W3C Validator API down right now?

W3C Validator answered our last daily check (Oct 24, 2026, 12:25 UTC) in 283 ms with HTTP 200. This page also runs a live check from our server when you open it, so you can see whether W3C Validator is responding at this moment.

How do you check whether W3C Validator API is up?

Once a day our checker requests W3C Validator's listed URL (https://validator.w3.org/docs/api.html) and records whether it answers within 15 seconds. Answers like 401 (needs a key), 403 (blocks bots) or 429 (rate-limited) count as up, because the server responded. The listed URL is often the documentation page, so an API endpoint can occasionally fail while its docs stay up.

What can I use if W3C Validator API is down?

Free Development APIs that were up at their last check include Icanhazip, Index Agentica, Open VSX. See the full list of W3C Validator alternatives for a comparison.

Why does W3C Validator API work for others but not for me?

A 429 response means you're being rate-limited. Slow down, cache responses, and respect any Retry-After header. If calls fail only in the browser with a CORS error, W3C Validator may not allow cross-origin requests. Call it from your server instead. If it works from one network but not another, check firewalls, VPNs and regional blocks.