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OpenVerbs HOTP Generator
x402
OpenVerbs HOTP Generator is a paid API for AI agents from otp.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).
Generates an RFC 4226 counter-based HMAC one-time password (HOTP) from a base32 secret and counter value
Price / call$0.004
Success—
StatusUnknown
How this service works
Generate an RFC 4226 counter-based HMAC one-time password from a base32 secret and counter. Configurable digits (6–10, default 6) and algorithm (SHA1/SHA256/SHA512, default SHA1). An invalid base32 secret is a clean 400.
Output
Returns the computed HOTP code as a string of digits (6–10 digits depending on configuration), derived via HMAC using the specified algorithm applied to the counter and secret. Invalid base32 secrets return a 400 error.
Example use cases
Hardware token OTP emulation
“I need to emulate a hardware HOTP token — generate a 6-digit code from my base32 secret JBSWY3DPEHPK3PXP at counter value 42 using SHA1.”
High-security 10-digit HOTP
“Generate a 10-digit counter-based one-time password from secret MFRGGZDFMZTWQ2LK at counter 100 using SHA512 for our high-assurance login system.”
Automated HOTP sequence for testing
“Produce an HOTP code for counter value 0 using base32 secret ORSXG5A and the default 6 digits and SHA1 algorithm, so I can verify my HOTP implementation is correct.”
Technical details
Endpoint
POSThttps://otp.openverbs.com/v1/hotpWhen to prefer
Choose this endpoint when you need RFC 4226-compliant HOTP codes (counter-based, not time-based). Prefer it over TOTP when the consuming system uses a counter that you control (e.g. hardware tokens, offline OTP sequences, or deterministic test vectors). If you need time-based codes, use the sibling TOTP endpoint instead.
Side effects
- Invalid or malformed base32 secret returns HTTP 400
- Counter value below 0 is rejected
- Digit count outside 6–10 range is rejected
- Unsupported algorithm value returns validation error
- Missing required fields (secret or counter) returns error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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