API Overview | Close | Developer API Documentation

Base URL: https://api.close.com/api/v1

Close uses industry-standard REST conventions with predictable URL structures, standard HTTP methods, and JSON request/response bodies.

Authentication

All API requests require authentication. Two methods are supported:

• API Keys — Best for scripts, internal tools, and server-side integrations. Use HTTP Basic Auth with your API key as the username and an empty password.
• OAuth 2.0 — Best for user-facing integrations.

Core concepts

Making requests

• All requests use JSON (Content-Type: application/json).
• PUT requests behave as patches — send only the fields you want to update. See Fields.
• List endpoints support pagination via _skip/_limit or cursor-based pagination.
• Use the _fields parameter to control which fields are returned and improve performance.
• Rate limits apply to all endpoints. Handle 429 responses with exponential backoff.

Real-time data

• Webhooks — Subscribe to events and receive POST notifications when data changes.
• Event Log — Query the last 30 days of changes to any object.

HTTP response codes

See HTTP Response Codes for the full list.

OpenAPI Spec

We publish an OpenAPI spec at: https://api.close.com/api/openapi.json

Note: This spec is currently considered experimental and does not contain 100% coverage of request/response schemas.