# fapi

Source: https://startwithidentity.com/glossary/fapi/
Last updated: 2026-08-29
License: content by Start with Identity. Cite the source URL.

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Financial-grade API. A hardened OAuth and OIDC security profile from the OpenID Foundation for high-risk APIs such as open banking, mandating stronger client authentication and request integrity.

FAPI is what OAuth looks like when the money is real: sender-constrained tokens, pushed authorization requests, strong client authentication, and signed request objects, all mandatory rather than optional. It became the de facto baseline for open banking worldwide, which means it is also the best available template for any high-value API even outside financial services. If you are securing payment initiation or account access, start from FAPI rather than from plain OAuth.

See also: [FAPI standard](https://startwithidentity.com/standards/fapi/), [PAR](https://startwithidentity.com/glossary/par/), [mTLS](https://startwithidentity.com/glossary/mtls/), [PSD2](https://startwithidentity.com/glossary/psd2/)