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What is the Calmony Open Banking Service API?

The Calmony Open Banking Service API allows developers to integrate with Calmony bank accounts, retrieve financial data, and manage Open Banking connections programmatically. The API is due to be available from Q2 2026.

The Calmony Open Banking Service API provides a standardised way for developers to access financial data and manage Open Banking connections within the Calmony platform, with minimal UI development required.

Availability

The Calmony Open Banking Service API is due to be available from Q2 2026. If you would like to be notified when access becomes available, or if you have questions in the meantime, please contact the Calmony team at support@calmony.co.

What the API can do

The API enables connected applications to:

  • View all registered bank accounts in the system
  • Retrieve detailed account information, including account numbers, sort codes, and payment links
  • Register new bank accounts to the platform
  • Verify whether a specific bank account exists in the system
  • Retrieve bank statement entries and transaction history within specified date ranges
  • Generate authentication URLs to connect bank accounts to Open Banking services
  • Manage existing Open Banking connections by refreshing tokens and checking connection status
  • Disconnect bank accounts from Open Banking when needed
  • Register payees for sanctions and AML checking
  • Retrieve sanctions, AML, and Griffin verification information for payees

How Open Banking authentication works

The Open Banking integration uses a user-centric authentication flow:

  1. Your application collects basic account details from the user (account number and sort code)
  2. Your application requests an authentication URL from the API
  3. The user is directed to that URL, where they authenticate directly with their bank
  4. After successful authentication, TrueLayer automatically redirects the user back to the Calmony system
  5. Calmony then automatically completes the setup and imports bank transactions

This approach ensures that the user's banking credentials are only ever shared with their own bank, maintaining security and compliance with Open Banking regulations.

Authentication requirement

All API requests must be authenticated using both an API key and ED25519 cryptographic message signatures. Requests without valid signatures will be rejected.

Further information

For full technical documentation, including endpoint references, message signing guidance, security best practices, and troubleshooting, visit the Calmony Open Banking Service API Documentation.

For support or to register your interest ahead of the Q2 2026 release, contact the Calmony team at support@calmony.co.