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The Grain API lets you build integrations that read and write church accounting data: transactions, bills, donors, contributions, pledges, and households.
REST API and MCP access are included on the Enterprise plan. Organization API keys and OAuth integrations require an active Enterprise subscription for the church you are accessing.

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What you can build

Accounting sync

Sync bank transactions and vendor bills into your workflows.

Giving data

Read contributions, pledges, and donor records for reporting or ChMS bridges.

Households

Manage household groupings and primary contacts.

OAuth apps

Authenticate users with Sign in with Grain (OAuth 2.1 + PKCE).

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Base URL

For local development, use your server URL (for example http://localhost:3000).

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Prerequisites

Use an organization API key for church-owned server automation, or an OAuth 2.1 access token for an application acting on behalf of a user. OAuth requests also need X-Organization-Id; API keys infer their organization. Start with the API key quickstart, then see Authentication for OAuth and credential lifecycle details.

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Rate limits

Rate limit headers are included on responses:
Contact Grain Support for higher limits on enterprise integrations.

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Next steps

Quickstart

Make your first authenticated API call in under 10 minutes.

Authentication

Set up OAuth 2.1 with PKCE and token refresh.

API reference

Browse endpoints grouped by resource.

Support

Get help from the Grain team.
Last modified on July 13, 2026