KPN

KPN Developer Portal offers comprehensive telecom and communication APIs with OAuth 2.0 and JWT authentication.

The platform includes CPaaS services for SMS, WhatsApp, messaging, voice calling, identity management (Grip), mobile service management, and knowledge management. Extensive documentation with Postman collections and OpenAPI specs available on GitHub. Free sandbox testing with production-like data. However, production access requires KPN business contracts for most APIs.

Ideal for businesses needing communication infrastructure, customer engagement solutions, and enterprise mobile fleet management with high-quality telecom services.