# Citi API Authentication Services

**Canonical:** https://apis.io/apis/citi/citi-api-authentication-services/  
**Provider:** Citi — https://apis.io/providers/citi/  
**Base URL:** https://tts.apib2b.citi.com/citiconnect/prod  
**Documentation:** https://developer.citi.com/apidocs/authentication/authentication-only-guide

Citi API Authentication Services is one of 12 APIs that [Citi](https://apis.io/providers/citi/) publishes on the [APIs.io](https://apis.io/) network, described by a machine-readable OpenAPI specification. Tagged areas include Authentication, OAuth, and Security. The published artifact set on APIs.io includes API documentation, an API reference, an OpenAPI specification, and authentication docs.

OAuth 2.0 token issuance for every Citi institutional API. Four concurrent versions (V1-V4) of the authentication endpoint are published; each product API's own specification names the version it requires. V1-V3 additionally require the request payload to be signed and encrypted with asymmetric PKI keys over mutual TLS; V4 removes the signing and encryption requirement. Citi publishes 4 machine-readable specifications for this family covering 4 operations, served from developer.citi.com.

## Operations (1)

| Method | Path | Summary |
|---|---|---|
| POST | `/authenticationservices/v1/oauth/token` | Request v1 Access Token |

## Machine-readable artifacts (12)

- **Documentation** — https://developer.citi.com/apidocs/authentication/authentication-only-guide
- **APIReference** — https://developer.citi.com/apidocs/authentication/authentication-api-reference
- **OpenAPI** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/openapi/citi-authentication-api-1-openapi.yaml
- **OpenAPI** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/openapi/citi-authentication-api-2-openapi.yaml
- **OpenAPI** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/openapi/citi-authentication-api-3-openapi.yaml
- **OpenAPI** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/openapi/citi-authentication-api-4-openapi.yaml
- **Overlay** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/overlays/citi-authentication-overlay.yaml
- **Authentication** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/authentication/citi-authentication.yml
- **Conventions** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/conventions/citi-conventions.yml
- **ErrorCatalog** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/errors/citi-problem-types.yml
- **Sandbox** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/sandbox/citi-sandbox.yml
- **APIsJSON** — https://raw.githubusercontent.com/api-evangelist/citi/refs/heads/main/apis.yml

## Other Citi APIs (11)

- [Citi Account Reporting APIs](https://apis.io/apis/citi/citi-account-reporting-apis/)
- [Citi Outgoing Payments APIs](https://apis.io/apis/citi/citi-outgoing-payments-apis/)
- [Citi Payment Acceptance APIs](https://apis.io/apis/citi/citi-payment-acceptance-apis/)
- [Citi Commercial Cards and Virtual Card Accounts APIs](https://apis.io/apis/citi/citi-commercial-cards-and-virtual-card-accounts-apis/)
- [CitiFX Gateway and Instant FX APIs](https://apis.io/apis/citi/citifx-gateway-and-instant-fx-apis/)
- [Citi Custody and Securities Services APIs](https://apis.io/apis/citi/citi-custody-and-securities-services-apis/)
- [Citi Funds Transfer Agency APIs](https://apis.io/apis/citi/citi-funds-transfer-agency-apis/)
- [Citi Open Banking APIs](https://apis.io/apis/citi/citi-open-banking-apis/)
- [CitiConnect Trade Services APIs](https://apis.io/apis/citi/citiconnect-trade-services-apis/)
- [Citi Gateway Services API](https://apis.io/apis/citi/citi-gateway-services-api/)
- [Citi Additional Payment Services APIs](https://apis.io/apis/citi/citi-additional-payment-services-apis/)

## Tags

Authentication, OAuth, Security

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/citi/citi-api-authentication-services/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/citi/.