Developer Documentation

REST APIs for automating UK company filings. Choose your integration path below.

Formation Agent API

Public self-service API for submitting CT600 nil returns to HMRC and dormant accounts to Companies House. Just 3-4 required fields per filing — we auto-derive the rest from Companies House.

Quickstart

Submit your first filing in 5 minutes.

API Reference

Complete endpoint documentation.

Authentication

API keys, rate limits, and security.

Sandbox

Test with magic company numbers.

Partner API

Private integration for white-label partners. Generate secure activation URLs and push trial balance data so the submission form is pre-populated when your customers arrive.

Partner Guide

Activation endpoints and trial balance imports.

OpenAPI Spec

Machine-readable spec for code generation.

Pricing: Formation Agent API filings cost £20 each, charged only on acceptance. Get your API key and top up your balance to get started.