OTP Gateway review
An open-source OTP server with a web UI, API and configurable delivery providers.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
OTP Gateway is an open-source, self-hosted web server for verifying phone numbers, email addresses and other user addresses. It is aimed at teams that want to run their own OTP service and connect it to existing applications through a web interface or HTTP/JSON API. A JavaScript modal plugin offers another way to add verification to an application, while namespace-based BasicAuth separates applications using the service.
Delivery options cover several channels and providers: SMTP email, SMS through AWS Pinpoint, and SMS or WhatsApp through Kaleyra. Webhook provider support gives teams a path to connect external delivery services. That flexibility makes OTP Gateway relevant when an organization wants control over the verification server and can select and manage its own delivery providers. The published feature set describes SMS verification; teams specifically seeking voice verification should look elsewhere.
As a self-hosted product, it places deployment and operation with the adopting team rather than offering a hosted service. OTP expiry and maximum attempts are configurable, giving implementers control over two parts of the verification flow. It is distributed under the MIT license. The fit is strongest for teams comfortable managing a server and arranging external message delivery; teams seeking a turnkey hosted phone verification service or voice-based flows should consider alternatives.
OTP Gateway pros and cons
- Where it wins
- Web UI and HTTP/JSON API support verification flows
- Configurable OTP expiry and maximum attempts
- Supports SMTP, AWS Pinpoint, Kaleyra and webhook providers
- Where it doesn't
- Self-hosted deployment requires operating the server
- SMS and WhatsApp delivery depend on external providers
- Voice verification is not documented
OTP Gateway fact sheet, pricing and score →
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