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Harmony Public API

The Harmony Public API lets your own code push contacts into Harmony, update them, and read them back.

Who it is for​

The API is for developers working on their own Account: syncing contacts from a CRM or data warehouse, or starting outreach from an internal tool. Each API key acts as the Harmony user who created it, inside that user's Account.

Building an integration that many Harmony customers install is not supported yet.

Limits​

The API has no published rate limits yet.

Next steps​

  • Quickstart: create a key and make your first call.
  • Errors: the error format and how to report a problem.
  • AI tools (MCP): connect Claude Code, Codex, Cursor, or VS Code to your Harmony data.