{"openapi":"3.1.0","info":{"title":"HTTP Header Checker","description":"Sends a request to a web address you provide and reports back everything the server said in response: the status code, all the response headers, how many times it got redirected, and how long the whole thing took.","version":"1.0.0","contact":{"name":"_done","url":"https://forms.gle/5KzuSFH7p8hHtDmz7","email":"info@underscoredone.com"},"x-openapi-url":"https://http-header-checker.underscoredone.com/openapi.json","x-logo":{"url":"https://underscoredone.com/logo.png","altText":"_done"},"x-guidance":"Call this when you need to inspect what a web server returns before downloading content, such as checking caching rules, security headers, redirect chains, or content types. Provide a full URL with http:// or https://. Do not use this to scrape page content, only headers and status metadata are returned.","x-ai-instructions":"Call this when you need to inspect what a web server returns before downloading content, such as checking caching rules, security headers, redirect chains, or content types. Provide a full URL with http:// or https://. Do not use this to scrape page content, only headers and status metadata are returned.","x-provider":"_done — single-purpose utility APIs for developers and AI agents. Pay per call with USDC on Base Mainnet or Solana Mainnet.","x-pricing":{"model":"pay-per-call","currency":"USDC","network":"Base Mainnet or Solana Mainnet","price":"$0.01"},"x-keywords":["network","http header checker","headers","url lookup","redirect check","security headers","cache control","status code","web debugging","utility","api","ai-agent","pay-per-call","usdc","x402"],"x-category":"network","x-provider-url":"https://underscoredone.com","x-agentcash-auth":{"mode":"paid"},"x-402":{"price":"$0.01","network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","pay_to":"0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08","facilitator":"https://api.cdp.coinbase.com/platform/v2/x402","scheme":"exact","description":"Sends a request to a web address you provide and reports back everything the server said in response: the status code, all the response headers, how many times it got redirected, and how long the whole thing took.","mime_type":"application/json","networks":[{"network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","pay_to":"0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08"},{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","asset":"EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v","pay_to":"8ugAWAXDB8V18kiUrGZTq1oMvU3C6Fxs8hfC6rvzQT3b"}]}},"paths":{"/check":{"post":{"tags":["Network"],"summary":"Look up the response headers and status of any URL","description":"Checks a web address and reports back its status, headers, redirect path, and timing.","operationId":"handler_check_post","requestBody":{"content":{"application/json":{"schema":{"$ref":"#/components/schemas/Request"}}},"required":true},"responses":{"200":{"description":"Successful response","content":{"application/json":{"schema":{"$ref":"#/components/schemas/Response"},"examples":{"success":{"summary":"Successful response","value":{"api_version":"1.0.0","url":"https://example.com","final_url":"https://example.com/","status_code":200,"redirect_chain":[{"url":"http://example.com","status_code":301}],"headers":{"content-type":"text/html; charset=UTF-8","server":"nginx","cache-control":"max-age=600","content-length":"1256"},"missing_security_headers":["strict-transport-security","content-security-policy"],"response_time_ms":214}}}}}},"422":{"description":"Unprocessable — a required field is missing or the wrong type. Check the detail field for specifics.","content":{"application/json":{"schema":{"type":"object","properties":{"detail":{"type":"array"}}}}}},"402":{"description":"Payment required. Send a signed USDC payment on Base Mainnet or Solana Mainnet using the x402 protocol.","headers":{"X-Payment-Response":{"description":"x402 payment challenge — base64-encoded JSON with payment details.","schema":{"type":"string"}}}},"400":{"description":"Bad request — your input failed validation or could not be processed. Check the detail field for specifics.","content":{"application/json":{"schema":{"type":"object","properties":{"detail":{"type":"string"}}}}}}},"x-ai-instructions":"Call this when you need to inspect what a web server returns before downloading content, such as checking caching rules, security headers, redirect chains, or content types. Provide a full URL with http:// or https://. Do not use this to scrape page content, only headers and status metadata are returned.","x-guidance":"Call this when you need to inspect what a web server returns before downloading content, such as checking caching rules, security headers, redirect chains, or content types. Provide a full URL with http:// or https://. Do not use this to scrape page content, only headers and status metadata are returned.","x-payment-info":{"price":{"fixed":{"mode":"fixed","currency":"USD","amount":"0.01"}},"protocols":[{"x402":{}}]}}}},"components":{"schemas":{"HTTPValidationError":{"properties":{"detail":{"items":{"$ref":"#/components/schemas/ValidationError"},"type":"array","title":"Detail"}},"type":"object","title":"HTTPValidationError"},"RedirectHop":{"properties":{"url":{"type":"string","title":"Url","description":"The address that redirected onward"},"status_code":{"type":"integer","title":"Status Code","description":"The status number the server gave at this step"}},"type":"object","required":["url","status_code"],"title":"RedirectHop","example":{"status_code":301,"url":"http://example.com"}},"Request":{"properties":{"url":{"type":"string","title":"Url","description":"The full web address to check, including http:// or https://"},"method":{"anyOf":[{"type":"string"},{"type":"null"}],"title":"Method","description":"Either GET or HEAD. GET fetches the page normally, HEAD only asks for headers without the body.","default":"GET"},"follow_redirects":{"anyOf":[{"type":"boolean"},{"type":"null"}],"title":"Follow Redirects","description":"Whether to follow redirects to their final destination or stop at the first one.","default":true}},"type":"object","required":["url"],"title":"Request","example":{"follow_redirects":true,"method":"GET","url":"https://example.com"}},"Response":{"properties":{"api_version":{"type":"string","title":"Api Version","description":"The version number of this service","default":"1.0.0"},"url":{"type":"string","title":"Url","description":"The web address that was requested"},"final_url":{"type":"string","title":"Final Url","description":"The web address the check actually ended up at, after any redirects"},"status_code":{"type":"integer","title":"Status Code","description":"The status number the web server sent back"},"redirect_chain":{"items":{"$ref":"#/components/schemas/RedirectHop"},"type":"array","title":"Redirect Chain","description":"Each step the check was redirected through, if any"},"headers":{"additionalProperties":{"type":"string"},"type":"object","title":"Headers","description":"All the information the web server sent back about the page"},"missing_security_headers":{"items":{"type":"string"},"type":"array","title":"Missing Security Headers","description":"Common protective settings that the web server did not include"},"response_time_ms":{"type":"number","title":"Response Time Ms","description":"How long the check took, in thousandths of a second"}},"type":"object","required":["url","final_url","status_code","redirect_chain","headers","missing_security_headers","response_time_ms"],"title":"Response","example":{"api_version":"1.0.0","final_url":"https://example.com/","headers":{"content-type":"text/html; charset=UTF-8","server":"nginx"},"missing_security_headers":["content-security-policy","strict-transport-security"],"redirect_chain":[{"status_code":301,"url":"http://example.com"}],"response_time_ms":214.0,"status_code":200,"url":"https://example.com"}},"ValidationError":{"properties":{"loc":{"items":{"anyOf":[{"type":"string"},{"type":"integer"}]},"type":"array","title":"Location"},"msg":{"type":"string","title":"Message"},"type":{"type":"string","title":"Error Type"},"input":{"title":"Input"},"ctx":{"type":"object","title":"Context"}},"type":"object","required":["loc","msg","type"],"title":"ValidationError"}},"securitySchemes":{"siwx":{"type":"apiKey","in":"header","name":"SIGN-IN-WITH-X","description":"CAIP-122 wallet signature for repeat access after payment"}}},"servers":[{"url":"https://http-header-checker.underscoredone.com","description":"Production"}],"x402Version":2,"x-payment-accepts":[{"scheme":"exact","network":"eip155:8453","payTo":"0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"},{"scheme":"exact","network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","payTo":"8ugAWAXDB8V18kiUrGZTq1oMvU3C6Fxs8hfC6rvzQT3b","asset":"EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"}]}