# Calling the API

Calls to the Transact API can be made in any programming language. The specific API calls you want to make
will depend on your use case and business requirements.

Each API endpoint has its own scope and Resource Owner type (role) requirements, documented for
each endpoint under _Authorisation Requirements_. If your request does not satisfy scope or role requirements, the API will return a
`401 Unauthorized` HTTP status code. For more information, see [Scopes and Roles](../advanced/scopes.md).

## Make a call

All calls to the Transact API **must** include:

- a `Transact-Api-Version` header specifying the API version to use
- an `Authorization` header providing a valid access token using the HTTP Bearer scheme.

For example, using cURL to call `GET /advisers` might look like the following:

```shell
curl \
  -H "Authorization: Bearer <token>" \
  -H "Transact-Api-Version: 2026-05-12" \
  https://apidemo.transact-online.co.uk/advisers
```

## What's next

- Follow a [guide](../guides/account-opening.mdx)
- Browse the [API reference](/api)
- Learn more about...
  - [Environments](../advanced/environments.md)
  - [Scopes and roles](../advanced/scopes.md)
  - [Error handling](../advanced/errors.md)
  - [Token claims](../advanced/tokens.md)
  - [Pagination](../advanced/pagination.md)
  - [Rate limits](../advanced/rate-limiting.md)