# Documentation and API reference

> Where to find what: the help for the application, the API reference and the guides for wiring up your tests. All three exist in English and in French.
> https://facteur.eu/en/documentation

## Three sets of docs, and which one to open

The help for the application, the API reference and the integration guides each answer a different question. The help is on this site, the reference and the guides on developers.facteur.eu.

## What each one holds

You open one according to what you are doing: clicking around the application, writing the code that calls the API, wiring that code into your test suite.

#### Help for the application

Creating an inbox, the address that receives the emails your tests trigger. Then reading a message, understanding a quota you have hit, inviting a colleague, wiring up SSO, recovering a lost second factor. Screen by screen.

#### API reference

Every route under /v1: its fields, its error codes, what a key must be allowed to do to call it, and what the API refuses whatever the key. It is built from the API’s OpenAPI document, so it cannot describe a route the service does not serve.

#### Integration guides

The path to a first call: a key, an inbox, a message received, an assertion that passes. Then authentication, the shape of errors, the server-side wait that replaces your retry loops, and picking up a suite written for Mailosaur.

## I want to…

If you know what you want to do but not where it is written, start here. And if your need is missing from the list, write to us: that is a page we have yet to write.

- I want to…
- It is written

- watch a test read a real email before I write my own
- receive a message in my tests and read the code inside it
- install a package into Playwright or Cypress rather than call the API
- know the exact fields of a response, or what an error code means
- create an API key and know what it can reach
- understand a quota I have hit, or change an inbox retention
- invite a colleague, partition a workspace, wire up SSO
- pick up a test suite written for another provider
- know what it costs, and from what volume
- know where my data sits and what the DPA commits to
- know whether the service is answering right now

## What is translated, and what is not

- All three exist in English and in French. Pick yours at the top of the page: the developer portal remembers the choice and serves you the next pages in that language.
- What you read is translated, what you type never is. A field name, a path such as /v1/inboxes, an error code such as quota_exceeded are written in English in both versions: that is what the API expects, and what it returns.
- The API error messages come back in English, whatever language you read in. Assert on the error.code field, never on the sentence beside it: the code does not change, the sentence can be rewritten.