---
title: "Developers"
description: "The Custom One public API — create and enrich leads, and subscribe to lead-journey events."
slug: "en/developers"
url: "https://docs.custom.one/en/developers/"
capability: "integrations"
published_at: "2026-10-26T04:39:33.778Z"
---
The public API lets external tools work with Custom One programmatically: build
and publish a custom, create and enrich leads in it, read its columns, and
subscribe to lead-journey events (webhooks). It is the same API an AI assistant
works through, and the one an automation platform such as Make, Zapier or n8n
uses with a key.

Authenticate every request with a workspace API key. Create one under
**Integrations**, on the **AI assistants** or **Automations** tab — see
[API keys and permissions](/en/integrations/api-keys/). The key prefix selects
the environment: `co_live_…` targets production, `co_test_…` targets
development.

- [API reference](/en/developers/api-reference/) — every endpoint, request and
  response, and a link to the machine-readable OpenAPI document.
- [AI assistants (MCP)](/en/developers/ai-assistants/) — connect Claude, ChatGPT or
  another assistant to a workspace, with no key to copy (tools configured by file,
  like Cursor, take a key).