---
title: "Build powerful integrations with Billabex"
description: "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."
canonical: https://developer.billabex.com/en/
lang: en
alternate: https://developer.billabex.com/fr/
last-updated: 2026-09-12
---

# 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.

Source: https://developer.billabex.com/en/
Language: English (en)
French version: https://developer.billabex.com/fr/

## 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

## 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

## Machine-readable resources

- [Billabex OpenAPI specification](https://developer.billabex.com/openapi.json): Typed REST operations, unique operation IDs, OAuth scopes, and JSON error schemas.
- [Billabex MCP server manifest](https://developer.billabex.com/mcp-server.json): Registry-compatible metadata for the Streamable HTTP MCP server.
- [Billabex agent instructions](https://developer.billabex.com/llms.txt): When to use Billabex, how to authenticate, and where to find each developer resource.
- [Billabex agent skill](https://developer.billabex.com/.well-known/agent-skills/index.json): The Agent Skills discovery index, with the digest of the skill it names.
- [Billabex developer hub](https://developer.billabex.com/developers/): Credentials, quickstart, environments, and every machine-readable contract on one page.

## Explore the API

- [Guides](https://developer.billabex.com/en/guides/)
- [API Reference](https://developer.billabex.com/en/api-reference/)
- [OAuth](https://developer.billabex.com/en/guides/oauth/)
- [Scopes](https://developer.billabex.com/en/guides/scopes/)

---

Billabex developer portal. OpenAPI specification: https://developer.billabex.com/openapi.json.
Agent instructions: https://developer.billabex.com/llms.txt. Complete documentation: https://developer.billabex.com/llms-full.txt.