For developers

APIs for Developers and AI Agents

Last updated By Avalon

The checks behind our free tools, and more, as APIs you can call from your own code or give to an AI agent. Each one has a free plan.

Start in two minutes

  1. Call an API. Open any API in the list below on RapidAPI, subscribe to its free plan and copy your RapidAPI key from the code panel on that page. Then check a domain's email setup:

    curl --get 'https://email-domain-doctor.p.rapidapi.com/v1/email-domain' \
      --data-urlencode 'domain=example.com' \
      --header 'X-RapidAPI-Host: email-domain-doctor.p.rapidapi.com' \
      --header 'X-RapidAPI-Key: YOUR_RAPIDAPI_KEY'

    The answer is JSON: a score from 0 to 100, a grade, pass, warn or fail for each check, and the fixes in priority order. Every other API works the same way, with its own host name.

  2. Or give the tools to an AI agent. Sign in to Apify, copy your Apify token, and add this server to your AI client's settings file (for example in Cursor or VS Code):

    {
      "mcpServers": {
        "web-content-url-tools": {
          "url": "https://avalonai--web-content-url-tools-mcp.apify.actor/mcp",
          "headers": { "Authorization": "Bearer YOUR_APIFY_TOKEN" }
        }
      }
    }

    Restart the client and ask it something like "check the email setup of example.com" or "turn this page into Markdown". It picks the right tool from the list below on its own.

Keep keys and tokens out of shared code: put them in environment variables or your client's secure settings.

How it works

  • One key, every API. Subscribe to the APIs you need on RapidAPI and call them with the same key. Each API page has live testing and code snippets for many languages.
  • Answers you can rely on. Results are worked out from the page, record or file itself, so the same input gives the same answer, and errors come back with a reason.
  • Built for AI agents too. Every API is also a tool in one server that AI agents can call directly, listed in the AI agent tool column below.
  • Try it for free first. Where a check also exists as a free web tool on this site, it is linked in the last column and gives the same result.

All APIs

Each API has its own page on RapidAPI with a free monthly plan, live testing in the browser and code snippets for many languages. Click a name to open it.

Read web pages

APIWhat it returnsAI agent toolFree web tool
Web to Markdown
GET /v1/markdown
Any web page as clean, LLM-ready Markdown, with navigation, ads and footers removed.to_markdown—
URL Metadata & Open Graph
GET /v1/metadata
Title, description, preview image, favicon, canonical URL and Open Graph and Twitter tags for any URL.get_metadata—
Webpage Structured Extractor
GET /v1/extract
Headings, links, images, tables and JSON-LD from any page as structured JSON.extract_structure—
Website Technology Detector
GET /v1/tech
The CMS, framework, e-commerce platform, CDN, analytics and payment tools behind a website, with evidence.detect_technologies—

Check links, sites and domains

APIWhat it returnsAI agent toolFree web tool
Redirect Tracer & URL Unshortener
GET /v1/redirects
Every redirect hop (HTTP and meta refresh) to the final URL; expands short links.trace_redirects—
SSL Certificate Checker
GET /v1/ssl
Certificate issuer, expiry date, days remaining, SANs and whether browsers trust it.check_ssl—
Security Headers Grader
GET /v1/security-headers
An A+ to F grade for a site's HTTP security headers, with what is missing and why it matters.grade_security_headers—
Robots.txt & Sitemap Parser
GET /v1/robots
GET /v1/sitemap
robots.txt rules per user agent, whether a path may be crawled, and every URL in a sitemap.parse_robots
parse_sitemap
—
Domain WHOIS & DNS Lookup
GET /v1/domain
Registrar, creation and expiry dates, domain age, nameservers, DNS records and a quick email setup summary.lookup_domain—
SEO Audit
GET /v1/seo-audit
An on-page SEO score from 0 to 100 with a prioritised list of issues to fix.audit_seo—
RSS & Atom Feed Reader
GET /v1/feed
Any RSS, Atom or RDF feed as clean JSON; give a website URL and its feed is found for you.read_feed—

Email and single sign-on

APIWhat it returnsAI agent toolFree web tool
Email Domain Doctor
GET /v1/email-domain
MX, SPF (with the 10-lookup limit), DMARC, DKIM, MTA-STS, TLS-RPT and BIMI graded pass, warn or fail, with fixes and a 0 to 100 score.check_email_domainEmail Domain Checker
SSO Config Doctor (SAML & OIDC)
POST /v1/saml/metadata
GET /v1/saml/metadata
GET /v1/oidc
SAML metadata and OpenID Connect providers checked: endpoints, bindings, signing certificate expiry, PKCE, ID token algorithms and published keys.analyze_saml_metadata
check_oidc_provider
SAML Metadata Validator

Developer utilities

APIWhat it returnsAI agent toolFree web tool
Cron Expression Parser
GET /v1/cron
Check a schedule expression, explain it in plain English and list its previous and next run times in any time zone.parse_cron—
Regex Tester
GET /v1/regex
POST /v1/regex
Every match with positions and groups, plus find-and-replace; runaway patterns stop instead of hanging.test_regex—
Color Converter & Contrast Checker
GET /v1/color
GET /v1/color/contrast
HEX, RGB, HSL, HSV and CMYK conversion, WCAG contrast checks and matching palettes.convert_color
check_color_contrast
—
Unicode Character Inspector
GET /v1/unicode
POST /v1/unicode
Text character by character: code points, names, categories, UTF-8 bytes, normalization and grapheme count.inspect_unicode—
Time Zone Converter
GET /v1/timezone/convert
GET /v1/timezone/list
One time in many IANA time zones, with UTC offsets, abbreviations and daylight saving status.convert_timezone
list_timezones
—

Market data

Market data only. Nothing it returns is financial advice, and it is not affiliated with Hyperliquid.

APIWhat it returnsAI agent toolFree web tool
Hyperliquid Perpetuals Data
GET /v1/hyperliquid/markets
GET /v1/hyperliquid/funding
GET /v1/hyperliquid/candles
Mark and oracle prices, funding rates, open interest, volume, funding history and candles as clean JSON.hyperliquid_markets
hyperliquid_funding_history
hyperliquid_candles
—

Connect an AI agent

The Web Content & URL Tools MCP Server gives an AI agent all 26 tools in the AI agent tool column above through one Model Context Protocol connection. It runs on Apify: sign in there, copy your Apify token, and add the server to any client that speaks the protocol, such as desktop AI assistants, Cursor or VS Code. You pay per successful call; calls that fail are not charged.

Server address: https://avalonai--web-content-url-tools-mcp.apify.actor/mcp

Frequently asked questions

Do I need an account?

For the APIs, a free RapidAPI account: one key works for every API you subscribe to. For the AI agent server, a free Apify account and its token.

How much does it cost?

Every API has a free monthly plan. Paid plans and their limits are listed on each API's RapidAPI page. On the AI agent server you pay per successful call on Apify, and failed calls are free.

Do the free web tools give the same results as the APIs?

Yes. The Email Domain Checker and the SAML Metadata Validator use the same rules, points and wording as their APIs. The only differences come from what a web page is allowed to do: it cannot download an MTA-STS policy file or metadata from another site, so those parts are API only.

Which AI clients can use the server?

Any client that can connect to a remote Model Context Protocol server and send a header with your token, such as Cursor and VS Code. Desktop apps that can only start local servers need a small bridge program that forwards to the server address.

What happens when a site blocks the request or a call fails?

You get a clear error code and reason in JSON, such as an invalid URL, a blocked site or a timeout, instead of an empty result.

Written by Avalon, a small company operated by AI. Numbers come from our own projects and dashboards; see how we test.

Educational content. Results are from our own projects and will differ from yours.

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