Crédit Mutuel de Bretagne API Access & Open Banking

Crédit Mutuel de Bretagne (CMB) serves personal and business customers across Brittany, and open-banking.io lets you reach that account data on your own terms. Instead of wrestling with PSD2 certificates or a bank sandbox, you link CMB once in the open-banking.io dashboard and your balances and transactions flow in — decrypted locally with a key that never leaves your device.

How to connect Crédit Mutuel de Bretagne

Connecting happens entirely inside the open-banking.io web dashboard — there is no API call, code, or key involved in this step.

  1. Sign up for open-banking.io and set an encryption passphrase. Your keys are generated right there on your own device.
  2. In the dashboard, choose Crédit Mutuel de Bretagne and pick the account type you need — both business and personal are supported.
  3. You are redirected to Crédit Mutuel de Bretagne's own secure login, where you approve access under PSD2 consent.
  4. Your accounts sync back into your dashboard. Consent lasts up to 180 days, after which you simply re-approve on CMB's screen.

CMB does not publish a BIC through this service (BIC: not applicable), so there is nothing extra to look up — just select the bank and go.

Access your data

Once CMB is connected, reading the data programmatically is an optional developer step. From the Developers page, create an API key and export a credentials.json — this bundles the API key together with your private decryption key. From there you can use the CLI (openbanking accounts, openbanking transactions, openbanking sync), an SDK, or the REST API. Requests authenticate with the X-Api-Key header, and every response is decrypted locally with your own key. The CLI and SDK only read and sync connections you already made in the dashboard — they never establish the link themselves.

Because open-banking.io is zero-knowledge, its servers hold only your public key. An API key on its own returns ciphertext; without your private key the data stays unreadable to anyone, including open-banking.io. It is certificate-free and costs about EUR 3 per month.

Do I need a developer account to use Crédit Mutuel de Bretagne?

No. Connecting and viewing accounts works entirely in the dashboard. The API key and credentials.json are only for those who want programmatic access.

Can open-banking.io read my Crédit Mutuel de Bretagne data?

No. Decryption happens on your device with a key only you hold. The service stores your public key alone and never sees your plaintext.

Up to 180 days per approval. When it expires, you re-authorise directly on Crédit Mutuel de Bretagne's own consent screen.

Ready to start? Visit open-banking.io.