OTP flows on programmable SMS routing: a FastAPI implementation

Most OTP examples stop too early. They show how to generate a code, store it somewhere, and send an SMS through a provider that hides routing behind a black box. That works for demos. It breaks down when routing, pricing and delivery behavior matter. At BridgeXAPI, messaging is approached differently. Routing is not hidden. It is part of the application. To demonstrate that, we built a FastAPI OTP service on top of programmable SMS routing. This is not just an OTP example This is an example of what authentication flows look like when routing, pricing and delivery are part of your system — not abstracted away by a provider. The routing model Most messaging APIs follow this pattern: you define the message the provider selects the route pricing and delivery behavior are opaque In this model, routing is a black box. BridgeXAPI follows a different approach: the developer selects the route ( route_id ) pricing is tied to that route delivery behavior becomes predictable routing decisions live