# Overview

> What you can build on Fina, which API to use and how to authenticate.

Fina is the operating system for small businesses in the Dominican Republic: books, a wallet (**Fina Pay**) and vertical modules (farm, store, restaurant, barbershop, real estate, car rental). Everything a third party can use is a plain HTTPS + JSON API described by an **OpenAPI 3.1** spec.

| I want to… | Use | Credential |
| --- | --- | --- |
| Accept payments in my store, app or backend | [Fina Pay API](https://fina.do/developers/api-fina-pay.md) | Secret key `sk_live_…` |
| Build my own customer app or website for a Fina business | [Storefront APIs](https://fina.do/developers/storefront-apis.md) | App key of the module |
| Build a kitchen display / POS for my restaurant | [Restaurant staff API](https://fina.do/developers/api-staff.md) | Paired device + staff PIN |
| Automate AI media jobs with my credits | [Video Studio API](https://fina.do/developers/api-video-studio.md) | Personal key `fina_vs_…` |

### Conventions shared by every API

- Money is always an **integer in minor units** (`amount_minor`, `price_minor`…): `150000` = RD$1,500.00. Never a float.
- Timestamps are ISO 8601 in UTC (`2026-10-05T14:00:00.000Z`). Business dates (`YYYY-MM-DD`) are in Dominican Republic time (UTC−4).
- Requests and responses are `application/json`. Error codes are stable strings — branch on them, never on the message.
- Base host: `https://fina.do`. Every API is versioned in its path (`/v1`); breaking changes ship as a new version.

### Built for AI assistants

Every page of these docs is also Markdown (append `.md` to its URL). [llms.txt](https://fina.do/llms.txt) indexes them, [llms-full.txt](https://fina.do/llms-full.txt) has all of it in one file, and a read-only [MCP server](https://fina.do/developers/ai.md) lets Claude Code, Cursor and other assistants search the docs and read the OpenAPI specs.

Source: https://fina.do/developers#overview