# Class API Resources

Welcome! This hub collects all the essential resources for building against the **Class API**. Start with the quickstart, then dive into authentication flows (Authorisation Code, Resource Owner Password), refresh tokens, scopes, error handling, and our API structure.

## Quickstart

Get set up and make your first successful request in minutes.

- **[Using the API](/products/nowinfinity/resources/class-api-structure)** — environment setup, base URL, headers, a first “hello” call, and troubleshooting tips.


## Authentication & Authorisation

Learn how users and apps obtain tokens to call the Class API securely.

- **[Auth Overview](/products/nowinfinity/resources/authorising-partner-application-api-access)** — Identifying which flow to implement (Partner vs. Client)
- **[Authorisation Code Flow](/products/nowinfinity/resources/authorisation-code-flow)** — recommended OAuth 2.0 flow for web/native apps.
- **[Resource Owner Password Flow](/products/nowinfinity/resources/resource-owner-password-flow)** — legacy/edge case flow.
- **[Refresh Tokens](/products/nowinfinity/resources/refresh-tokens)** — how to obtain/rotate refresh tokens.
- **[Authorisation Scopes](/products/nowinfinity/resources/authorisation-scopes)** — available scopes and least-privilege examples.
- **[UserInfo Endpoint](/products/nowinfinity/resources/userinfo-endpoint)** — retrieving the authenticated user’s profile.
- **[SSO using Class API](/products/nowinfinity/resources/sso-using-class-api)** — high-level SSO patterns.


## API Structure & Discovery

- **[Class API Structure](/products/nowinfinity/resources/class-api-structure)** — service domains, resource naming, versioning strategy.


## Reliability & Best Practices

- **[Rate Limiting](/products/nowinfinity/resources/rate-limiting)** — limits, headers, and retry/backoff guidance.
- **[Error Codes](/products/nowinfinity/resources/error-codes)** — error taxonomy and actionable remediation.


## Reference

- **[API Reference](/products/nowinfinity/apis)** — full OpenAPI reference.