{"uid":"cap_plVp718ltHoa1EMekp0XC","slug":"agent402-stateless-captcha-challenge-generator-066db972","name":"Agent402 Stateless CAPTCHA Challenge Generator","description":"Mint a stateless captcha challenge to gate your OWN endpoint: returns a human prompt plus a salted sha256 answer hash you keep and verify later (sha256(salt + normalized answer) === answerHash) - no server state, no shared secret. Types: math (arithmetic) or alnum (character code), difficulty 1–3. Deterministic tooling for running bot protection, not defeating it.","url":"https://agent402.tools/api/captcha-generate","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"type":{"type":"string","description":"math | alnum (default math)"},"difficulty":{"type":"integer","description":"1–3 (default 1)"}}},"responseSchema":{"type":"json","example":{"algo":"sha256","salt":"…","type":"math","prompt":"What is 3 + 4?","verify":"sha256(salt + answer.trim().toLowerCase().replace(/\\s+/g,'')) === answerHash","answerHash":"…"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","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":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_AmTezJHuekssAqwxQV3Bw","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Generates a stateless CAPTCHA challenge (human prompt + salted SHA-256 answer hash) that you can use to gate your own endpoint without any server-side state.","exampleAgentPrompt":"Generate a difficulty-2 math captcha challenge I can use to gate my API endpoint — give me the human prompt and the salted SHA-256 answer hash so I can verify responses myself without any server state.","exampleUseCases":null,"resultDescription":"Returns a human-readable challenge prompt (e.g. a math question), a salt value, and a salted SHA-256 hash of the correct answer (sha256(salt + normalizedAnswer)). The caller keeps the hash and salt to verify user responses later without any server-side state or shared secrets.","failureModes":["Invalid 'type' value (not 'math' or 'alnum') — likely 400 or default fallback to math","Difficulty out of range (not 1–3) — likely 400 or clamped to nearest valid value","Payment failure (x402 protocol) — 402 Payment Required if USDC payment not included","Malformed JSON body — 400 Bad Request"],"whenToPreferThis":"Choose this endpoint when you need a lightweight, serverless CAPTCHA mechanism to gate your own API or endpoint without maintaining any server-side session or state. It is ideal for stateless microservices, edge deployments, or any scenario where you want challenge-response bot protection with zero infrastructure overhead. Prefer it over traditional CAPTCHA services when you don't want a third-party verify step or shared secret.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:12:29.809Z","isFirstParty":false}