OpenAPI Spec

The full BillerAPI Client API is described by a machine-readable OpenAPI 3.0 document. Use it to generate a typed client in your language, drive a mock server, or explore the API in any OpenAPI-aware tool.

Where to get it

The spec is served from the docs site and updated on every deploy. Fetch it directly:

GET https://docs.billerapi.com/openapi.json

The document declares two servers — https://sandbox.api.billerapi.com (sandbox) and https://api.billerapi.com (production). Point your generated client at the sandbox server while you build.

Authentication

The spec defines the same auth schemes documented in Authentication:

API key and API key header API keys for client-credentialed endpoints.
client-credentials — Bearer API-key auth as an alternative to the header keys.
jwt-auth — a Bearer access token for per-account operations (obtained via link token exchange).

The spec covers the client-facing surface only. Internal and agent-only endpoints are excluded.

Generate a client

Any OpenAPI generator works. Two common options:

Generate a typed client from the spec

# TypeScript types + a typed fetch client
npx openapi-typescript https://docs.billerapi.com/openapi.json \
  --output ./billerapi.d.ts

All field names in requests and responses are snake_case. Errors follow the coded error envelope (error_code, error_type, error_message, request_id). List endpoints use cursor pagination.

Official server SDK

An official @billerapi/node server SDK generated from this spec is planned. Until it ships, the spec above is the fastest path to a typed client. For the in-browser Connect and Pay flows, use the Elements SDK instead of a generated client.

API Reference — human-readable endpoint reference
Authentication — client credentials and bearer token auth
Error Handling — the coded error envelope the spec references
Pagination — cursor pagination shape used by list endpoints

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