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Agent402 Stateless CAPTCHA Challenge Generator
x402
Agent402 Stateless CAPTCHA Challenge Generator is a paid API for AI agents from agent402.tools, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).
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.
Price / call$0.001
Success—
StatusUnknown
How this service works
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.
Output
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.
Example use cases
Example prompt
“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.”
Technical details
Endpoint
POSThttps://agent402.tools/api/captcha-generateWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| type | string | math | alnum (default math) |
| difficulty | integer | 1–3 (default 1) |
Output
Schema · Response
{
"type": "json",
"example": {
"algo": "sha256",
"salt": "…",
"type": "math",
"prompt": "What is 3 + 4?",
"verify": "sha256(salt + answer.trim().toLowerCase().replace(/\\s+/g,'')) === answerHash",
"answerHash": "…"
}
}Tags
x402
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