> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.laposta.org/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.laposta.org/_mcp/server.

# Trying out the API with Try it

> Send a real call to the Laposta API from your browser, without installing anything.

On every endpoint page, you will find the ‘Try it’ button at the top right of the code example. This allows you to enter the parameters into a form and send the call directly from your browser. The response appears below it: the exact same JSON you would receive in your own code.

## Entering your API key

At the top of the form, paste your API key into the ‘api_key’ field. There is no password field, because the API does not require a password. You can read why this is the case under [Authentication with your API key](/api-authenticatie).

Your key remains in your own browser and is not sent to the creators of this site. The request goes directly from your browser to `api.laposta.nl`, over https.

## Please note: this is a real call

There is no separate test environment. If you enter a valid key and send a call that creates something, it will actually be created in your account.

> **Warning**
>
> Do not use a key from an account with a live subscriber base while you are testing things out. Also be careful if you are working on a shared computer: your key will remain saved in that browser until you clear it.

If you leave the field completely blank, nothing bad will happen. The call is sent without a key and the API responds with a `401`, because without a key the API does not know which account is being accessed. This error message is explained under [Authentication with your API key](/api-authenticatie).

## Testing safely with a separate list

You can test safely by creating a separate test list in your account. Create a single list, note down the `list_id` and direct all your test calls to it. Your live lists will then remain untouched, even if something goes wrong.

Creating a separate free test account is usually not an option; see [One free account per organisation](/er-is-al-een-gratis-account-voor-je-organisatie). If you are a developer and genuinely need an isolated environment, please contact the helpdesk at [helpdesk@laposta.nl](mailto:helpdesk@laposta.nl). It is possible to create multiple paid accounts, bundled in a management environment.

## Endpoints without Try it

For a number of endpoints, the ‘Try it’ button has been left out on purpose, because those calls cannot be undone or will start running automatically:

| Endpoint                                                          | Why not                                            |
| ----------------------------------------------------------------- | -------------------------------------------------- |
| All delete endpoints                                              | the object is permanently gone afterwards          |
| [Emptying a list](/lijsten/lijst-leegmaken)                       | deletes all subscribers in the list                |
| [Synchronising a list (bulk)](/lijsten/lijst-synchroniseren-bulk) | modifies up to 500,000 subscribers at once         |
| [Sending a campaign](/campagnes/campagne-verzenden)               | sends real emails to real recipients               |
| [Scheduling a campaign](/campagnes/campagne-inplannen)            | queues a campaign to be sent at the scheduled time |

The code examples are still provided on those pages, so you can see exactly what the call looks like.

## Choosing a programming language

Above the code example, you can select the programming language. On the endpoint page itself, there are nine options, ranging from cURL and PHP to Python, Go and Swift. In the ‘Try it’ screen, there are three (cURL, JavaScript and Python), because this shows a preview of your current input rather than the full list.

## Related articles

#### [Making your first API call](/je-eerste-api-aanroep)

Make your first API call and retrieve your lists, directly on this site or from your…

#### [How does authentication with your API key work?](/api-authenticatie)

The API uses basic auth, with your key as the username and an empty password.

#### [What are common mistakes with the API?](/veelgemaakte-fouten-met-de-api)

Pitfalls when integrating with the Laposta API, including the error message you get and…