> ## Documentation Index
> Fetch the complete documentation index at: https://api-doc.fidly.be/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Read and write a company's data over a stable HTTP interface.

The Fidly API lets a partner or third-party integration read and write a company's
data: documents (invoices, credit notes, received documents), relations, bank
accounts, journals and brandings.

## Base URL

```
https://api.fidly.be
```

All requests use HTTPS and JSON (except file upload and download endpoints, which use
`multipart/form-data` and raw bytes).

## Resources

| Resource                                              | Read | Create | Update | Delete |
| ----------------------------------------------------- | :--: | :----: | :----: | :----: |
| [Documents](/en/concepts/documents)                   |   ✅  |    ✅   |    ✅   |    ✅   |
| [Relations](/en/concepts/relations)                   |   ✅  |    ✅   |    ✅   |    ✅   |
| [Delivery locations](/en/concepts/delivery-locations) |   ✅  |    ✅   |    ✅   |    ✅   |
| [Bank accounts](/en/concepts/bank-accounts)           |   ✅  |    ✅   |    ✅   |    ❌   |
| [Journals](/en/concepts/journals)                     |   ✅  |    ✅   |    ✅   |    ❌   |
| [Brandings](/en/concepts/brandings)                   |   ✅  |    ❌   |   🟠   |    ❌   |
| [Reference lists](/en/concepts/reference-lists)       |   ✅  |    ❌   |    ❌   |    ❌   |

**Legend**:

* ✅ available
* 🟠 partially implemented — the endpoint exposes only part of the resource
* ❌ not available

🟠 **Brandings** — the `PATCH` only lets you designate the default branding; no
other field can be modified.

The business conditions of an action (edit lock on a sent document, fields fixed at
journal creation, deletion refused while other objects still reference the targeted
one...) are detailed on each resource's page.

<Warning>
  The API is more permissive than the interface. A document created through the API
  may therefore hold combinations the web or mobile application cannot represent, and
  displaying or editing it from the application may then cause issues. This applies
  in particular to VAT rates other than the Belgian legal rates (0, 6, 12 and 21 %),
  and to discounts and charges as soon as there is more than one per line or per
  document — without being limited to these two examples.
</Warning>

## Environments

Each API client works in one of two environments:

* **Live** — the company's real data, for both reads and writes.
* **Sandbox** — an isolated environment to develop and test: demo data, the exact
  same validations and error codes as live, and no stored changes. See
  [Sandbox](/en/sandbox).

The environment is determined by your credentials: a
`client_id` / `client_secret` pair belongs to either live or sandbox, and is
obtained from the Fidly interface.

## Authentication

Authentication relies on the OAuth2 client credentials flow. A call to
`POST /auth/token` with your `client_id` / `client_secret` pair returns your
`access_token` and `refresh_token` keys; every API call then carries the
`access_token` in the `Authorization` header. See
[Authentication](/en/authentication).

## Errors

All errors share one envelope with a machine-readable `code` and a human-readable
`message`. See [Errors](/en/errors).