Developer Portal

Build powerful integrations with Billabex

Automate payment follow-up with an AI-powered platform. Integrate through our REST API, OAuth 2.1 authentication with PKCE, and documentation that covers every endpoint.

Get startedAPI reference
REST APIOAuth 2.1OpenAPI

Production-ready endpoints with cursor-based pagination, token-based rate limiting, and OAuth 2.1 security.

https://next.billabex.com/api/public/v1

What is Billabex?

Billabex is an AI-powered accounts receivable platform that helps businesses recover outstanding payments faster. Its agent handles customer follow-ups in several languages, with tact and diplomacy.

Intelligent responses : the agent understands customer replies and adapts its communication
Multilingual support : it writes to customers in their preferred language
API-first platform : integrate it with your billing tools and your workflows

Developer experience

Production-ready features

OAuth 2.1 with PKCE : secure authorization code flow
Cursor-based pagination : efficient handling of large datasets
Rate limiting : token-based limits with clear headers
Comprehensive scopes : granular permission control
OpenAPI documentation : interactive API explorer
File uploads : multipart form-data for invoices and credit notes

Quick start

  1. Create an OAuth client in Developer Portal > OAuth Clients
  2. Implement the authorization code flow with PKCE
  3. Exchange the authorization code for access and refresh tokens
  4. Fetch your organizationId from GET /organizations
  5. Call the public API with your access token
  6. Handle pagination and rate limits
Start building

Machine-readable resources

Billabex OpenAPI specification

Typed REST operations, unique operation IDs, OAuth scopes, and JSON error schemas.

Billabex MCP server manifest

Registry-compatible metadata for the Streamable HTTP MCP server.

Billabex agent instructions

When to use Billabex, how to authenticate, and where to find each developer resource.

Explore the API

Guides

Step-by-step tutorials for authentication, pagination, rate limiting, and more.

API reference

Complete endpoint documentation with request and response schemas.

OAuth authentication

Secure your integration with OAuth 2.1 authorization code flow, PKCE, and optional OIDC.

OAuth scopes

Available permissions for invoices, accounts, communications, and organizations.

Ready to start building?

Follow the getting started guide to make your first API call in minutes. Learn how to authenticate, handle pagination, and manage resources programmatically.

Read getting startedExplore API reference