Build an Integration

Build an Integration

Connect your product or internal tools with Close.
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Close’s REST API supports everything from a simple internal script to a full product integration used by thousands of Close customers. If building AI Agent integrations, you may prefer to connect via the MCP server instead.

Choose an authentication method

There are two ways to authenticate with the Close REST API or MCP server.

  • API keys — A key is tied to a specific user and organization. Great for scripts, internal tools, import jobs, and automations. Generate one in Settings → Developer → API Keys and then follow API keys to authenticate your requests.
  • OAuth 2.0 — Lets each user authorize your app to act on their behalf. Strongly recommended for user-facing integrations that multiple users will authenticate to. See Creating an OAuth App to get started and then follow Authentication with OAuth to implement the request flow.

Access permissions inherit from the specific user/membership associated with the API key or OAuth token.

Internal integration

Building something for your own Close organization — an import script, a sync job, an internal dashboard, or an AI agent?

  1. Choose an authentication method — Either method described above can be a good choice for internal integrations.
  2. Build your integration — Use the API Reference to read and write Close data. Set up webhooks if you need real-time updates.

Multi-customer integration

Building a product that connects to your customers’ Close accounts? OAuth 2.0 is strongly recommended so each customer can authorize access to their own org.

  1. Create an OAuth App — Register your application in Close to get client credentials.
  2. Implement the OAuth 2.0 flow — Let users authorize your app and obtain access tokens.
  3. Build your integration — Use the API Reference to interact with Close data on behalf of each connected customer.
  4. Get listed — Submit your integration to the Close Integrations Directory to reach thousands of sales teams.

Dev/test organization

If you need a separate Close organization for development and testing:

  • Already a Close user — You can create a free secondary organization. See Secondary organization for instructions.
  • Not a Close user — Integration partners who don’t use Close in their own sales process can request a free Dev organization by emailing support@close.com with a description of your OAuth app, the overall workflow, and your expected release timeline. Dev organizations work identically to standard Close organizations but have no subscription fees.

Your OAuth app continues to work regardless of whether your Close account’s subscription is active, expired, or canceled.