Captcha Verification

The /captcha endpoint verifies an answer submitted for a challenge-mode captcha: send back the token from the X-Captcha-Token header, along with the text the user typed.

posthttps://api.moxon.dev/v5/captcha

Try itpost/v5/captcha

curl -X POST \  "https://api.moxon.dev/v5/captcha" \  -H "Content-Type: application/json" \  -d '{}'

Send the request to see the response here.

Parameters

The request body must be JSON:

tokenstringrequired
Token from the X-Captcha-Token header
answerstringrequired
Text typed by the user. Case-insensitive, trimmed

Response Fields

validboolean
true if the answer matches
reasonstring
Why it was rejected — absent when valid is true

Rejection Reasons

Reason	Meaning
`wrong`	The answer does not match the image
`expired`	The token is older than 5 minutes
`used`	The token was already redeemed — each one works exactly once
`invalid`	The token is malformed

Code Examples

curl -X POST \  "https://api.moxon.dev/v5/captcha" \  -H "Content-Type: application/json" \  -d '{    "token": "eyJ...",    "answer": "a4Kf2p"  }'

Error Handling

If parameters are missing or invalid, the API will return an error:

400Please provide a token (?token={token})The token is missing
400Please provide an answer (&answer={answer})The answer is missing

get/v5/captcha - Generate a captcha in challenge mode
get/v5/pow - Proof of work, the recommended alternative

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Last updated on September 8, 2026