Introduction

K-OTP lets you issue → deliver → verify phone verification codes (OTP) with two API calls. K-OTP generates the code, sends it by SMS or KakaoTalk AlimTalk, enforces expiry and attempt limits, deduplicates retries, and settles credits.

How it works

 Your server / browser          K-OTP API                     End user's phone
 ─────────────────────          ─────────                     ────────────────
 1. POST /v1/issue  ─────────▶  generate 6-digit code (hash only)
    (Idempotency-Key)           reserve credit + queue delivery
                     ◀───────── { issueId, expiresAt, ... }
                                2. send SMS or AlimTalk ─────▶  "[K-OTP] 인증번호는 123456..."
 3. POST /v1/verify ─────────▶  check issueId + code
    { issueId, code }           (expiry, max attempts, one-time)
                     ◀───────── { verified: true }

1. Issue — your service sends a phone number and a purpose to POST /v1/issue. K-OTP generates a 6-digit code server-side, reserves credit, and queues delivery. The response contains an issueId, never the code.
2. Deliver — K-OTP sends the code by SMS (default) or AlimTalk. Delivery is tracked asynchronously; check it with GET /v1/status.
3. Verify — send the code the user typed together with the issueId to POST /v1/verify. The response is always 200; read verified and, on failure, reasonCode.

Key concepts

URLs

Next steps