{"uid":"cap_ESBxm2z7dmvJ_8GPG5_E0","slug":"api-zfax-org-zfax-send-fax-016921e7","name":"ZFax Send Fax","description":"Send a PDF document to a real fax number through the default fax service for AI agents and automated workflows. The Worker validates, SHA-256 hashes, and counts the PDF before payment, then the live 402 challenge is sized to the exact page count at 90000 micro-USDC per page and scoped to that PDF digest, up to 100 pages.","url":"https://api.zfax.org/v1/faxes?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["to","pdfUrl"],"properties":{"to":{"type":"string","pattern":"^\\+[1-9]\\d{1,14}$","description":"Recipient fax number in E.164 format, e.g. +15551234567."},"from":{"type":"string","pattern":"^\\+[1-9]\\d{1,14}$","description":"Sender fax number in E.164 format. Optional; uses the service default if omitted."},"pdfUrl":{"type":"string","format":"uri","description":"Public HTTPS URL of the PDF to fax. For local files, prefer sending the PDF as the application/pdf request body."},"headerText":{"type":"string","pattern":"^[^\\r\\n]*$","maxLength":50,"description":"Text to display at the top of each fax page."}},"additionalProperties":false},"responseSchema":{"oneOf":[{"type":"object","required":["success","faxId","status","to"],"properties":{"to":{"type":"string"},"from":{"type":"string"},"faxId":{"type":"string"},"status":{"enum":["QUEUED","IN_PROGRESS","COMPLETED","FAILURE","UNKNOWN","STATUS_LOOKUP_FAILED"],"type":"string"},"message":{"type":"string"},"success":{"type":"boolean","const":true},"errorCode":{"type":"integer","maximum":9007199254740991,"minimum":0},"errorType":{"type":"string"},"createTime":{"type":"string"},"trackingUrl":{"type":"string","format":"uri"},"errorMessage":{"type":"string"},"billablePages":{"type":"integer","maximum":9007199254740991,"exclusiveMinimum":0},"numberOfPages":{"type":"integer","maximum":9007199254740991,"minimum":0},"amountUsdcMicro":{"type":"string","pattern":"^\\d+$"},"pricePerPageUsdcMicro":{"type":"string","pattern":"^\\d+$"}},"additionalProperties":false},{"type":"object","required":["success","status"],"properties":{"to":{"type":"string"},"from":{"type":"string"},"faxId":{"type":"string"},"status":{"enum":["QUEUED","IN_PROGRESS","COMPLETED","FAILURE","UNKNOWN","STATUS_LOOKUP_FAILED"],"type":"string"},"message":{"type":"string"},"success":{"type":"boolean","const":false},"errorCode":{"type":"integer","maximum":9007199254740991,"minimum":0},"errorType":{"type":"string"},"createTime":{"type":"string"},"trackingUrl":{"type":"string","format":"uri"},"errorMessage":{"type":"string"},"numberOfPages":{"type":"integer","maximum":9007199254740991,"minimum":0}},"additionalProperties":false}],"$schema":"https://json-schema.org/draft/2020-12/schema"},"example":null,"exampleRequest":null,"tags":[],"displayCostAmount":"0.09","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.09/call","primary":{"kind":"static","protocol":"mpp","network":"tempo","amountUsd":"0.09","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"mpp","network":"tempo","amountUsd":"0.09","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_MmR3f-OcgpWvc_KeJU73n","protocol":"mpp","methodType":"crypto","chain":"tempo","mode":"charge","costAmount":"0.09","costPer":"request","priority":0,"asset":null,"unit":"request","depositMicros":null,"planRef":null}],"brandName":"api.zfax.org","brandSlug":"api-zfax-org-mpp","brandBaseUrl":"https://api.zfax.org","brandDocsUrl":null,"whatItDoes":"Sends a PDF document to a real fax number, charged at 0.09 USDC per page (up to 100 pages) via micropayment.","exampleAgentPrompt":"Please fax the PDF at https://example.com/auth-form.pdf to +15551234567 — put 'Authorization Request' in the header on each page.","exampleUseCases":null,"resultDescription":"Returns a JSON object with success flag, faxId, delivery status (QUEUED/IN_PROGRESS/COMPLETED/FAILURE/UNKNOWN), tracking URL, billable page count, total USDC micro amount charged, price per page, sender/recipient numbers, and creation timestamp. On failure, returns success=false with errorType and errorMessage.","failureModes":["Invalid or unreachable PDF URL — returns success=false with errorType indicating fetch failure","Fax number not in E.164 format — schema validation error","PDF exceeds 100 pages — rejected before payment","Fax delivery failure after transmission — status=FAILURE with errorCode and errorMessage","Payment/402 challenge failure — fax not sent, payment not captured","PDF URL returns non-PDF content — validation error before payment"],"whenToPreferThis":"Use this endpoint when an AI agent or automated workflow needs to deliver a PDF document to a recipient who only accepts fax, with no subscription, hardware, or Sinch account required. Ideal for healthcare, legal, finance, and government use cases where fax is the required delivery channel. Pay-per-page pricing (0.09 USDC) via micropayment makes it suitable for low-volume or sporadic fax needs without a standing fax service contract.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":4,"lastUsedAt":"2026-05-05T04:54:19.516Z","lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-10T18:31:36.581Z","isFirstParty":false,"canonicalSlug":"api-zfax-org-zfax-send-fax-016921e7"}