SMS verification API built for production teams
Products that verify users by SMS need reliable infrastructure — not ad-hoc personal SIM cards. SMSTwins offers a documented REST API, signed webhooks, catalog discovery, activations, rentals, and tiered rate limits so businesses and integrators automate OTP workflows at scale.
Core capabilities
Request temporary numbers, poll or webhook-deliver OTP text, manage balance, and configure event endpoints. Provider gateway documentation covers the separate supply side for SIM partners.
Simple API mode returns plain text for legacy scripts. OpenAPI enables interactive exploration.
Security and compliance
Keys are hashed at rest; prefixes display in the dashboard for identification. Webhook HMAC verification prevents spoofed events. HTTPS is required in production.
API Terms of Use define acceptable integration behavior. Use verification APIs for lawful onboarding and testing — not harassment or fraud.
Scale and rate tiers
Free tier: 60 requests/minute. Standard (Bronze–Gold loyalty): 120/minute. Enterprise (Platinum): 600/minute. Limits apply per account across all keys.
Loyalty discounts reduce purchasePrice on every API activation automatically when authenticated.
Operational reliability
Non-VoIP provider routing, automatic refunds on failed activations, and status page transparency support SLA-minded teams. Enterprise customers can discuss custom limits and contacts.
Support channel available for integration questions and billing.
Onboarding checklist
Create account → issue API key → configure webhook URL → call catalog for prices → POST activation → handle sms.received event → complete your product flow.
Sandbox keys let you validate authentication before spending credits in staging.
Business API FAQ
- Is invoice billing available?
- Enterprise tier customers can discuss invoice options and custom SLAs with our team.
- How are webhooks retried?
- See documentation for delivery semantics and best practices on idempotent handlers.
- Can we whitelist IPs?
- Contact support for enterprise security discussions including rate limits and operational requirements.