BiG Spain API Access & Open Banking Data | open-banking.io

Pulling your BiG (Spain) account and transaction data no longer means chasing a bank sandbox or wrestling with eIDAS certificates. open-banking.io gives you a single, certificate-free path to your BiG data across more than 2,600 EU and UK banks — and because it is zero-knowledge, every balance and transaction is decrypted on your own device with a key that never leaves it. BiG (BIC IGSEESMMXXX) supports both business and personal accounts, with PSD2 consent lasting up to 180 days before you re-approve.

The service costs around EUR 3/month, with no per-call metering and no developer certificate to renew.

How to connect BiG

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

  1. Sign up for open-banking.io and set your encryption passphrase. Your keys are generated locally on your device at this moment, so only you can later unlock your data.
  2. In the dashboard, pick BiG from the bank list and choose your account type — business or personal.
  3. You are redirected to BiG's own secure login, where you approve access under PSD2 consent. Your credentials are only ever entered on the bank's site.
  4. Once approved, your BiG accounts sync straight into your open-banking.io dashboard, ready to view.

Access your data

Reading BiG data programmatically is an optional step you take after connecting. On the Developers page, create an API key and export a credentials.json — it bundles your API key with your private decryption key. From there, 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. Without that private key, the API key alone returns only ciphertext — open-banking.io's servers hold nothing but your public key and can never read your data.

Do I need an eIDAS certificate to reach BiG?

No. open-banking.io is certificate-free — you connect through BiG's consent screen without any QWAC or QSeal certificate.

Can open-banking.io see my BiG balances?

No. The platform is zero-knowledge: it stores only your public key, so all decryption happens on your device.

BiG grants consent for up to 180 days, after which you simply re-approve access from your dashboard.

Ready to start? Connect BiG at open-banking.io.