01
Generate or supply a code
Generate a numeric code of 4–8 digits, or supply a custom code of 4–16 letters, numbers, hyphens, or underscores. Set expiry from 1 to 60 minutes.
ONE-TIME PASSCODE ENGINE
OTP API for send and verify.
Send and verify one-time passcodes by email, SMS, or WhatsApp. Configure a delivery channel, then use the same API for generation, expiry, resend, and verification.
- Channels
- SMS · WhatsApp · Email
- Code TTL
- Configurable 1–60 min
- Wrong attempts
- 3, then the code burns
- Storage
- HMAC-hashed, never plaintext
What the OTP engine handles for you
02
Choose a delivery channel
Each request selects email, SMS, or WhatsApp. Configure the channel first; switching channels is an application decision, not an automatic cascade.
03
Limits on attempts and resends
Codes expire, verification attempts are capped, and resend cooldowns and recipient and tenant send limits help control repeated requests.
04
Verify on your backend
Call the verify endpoint from your server. Successful verification invalidates the code and returns a verification result with a token and timestamp.
OTP · request
POST /api/v1/otp/send
Authorization: Bearer <SENDRIN_API_KEY>
Content-Type: application/json
{
"channel": "sms",
"recipient_phone": "+919876543210",
"purpose": "login",
"ttl_seconds": 300
}
POST /api/v1/otp/verify
Authorization: Bearer <SENDRIN_API_KEY>
Content-Type: application/json
{
"channel": "sms",
"recipient_phone": "+919876543210",
"purpose": "login",
"code": "482913"
}Supported providers
- Configured SMS provider
- WhatsApp Cloud API
- Verified-domain email
Use an application API key on your server. SMS needs provider credentials; email needs a verified sending domain; WhatsApp needs a connected business number, approved authentication template, and recipient consent. See the OTP guide for setup and limits.
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