---
title: Testing a REST-API Connection
slug: how-tos/i9IG-testing-a-rest-apu
createdAt: 2025-09-09T10:06:06.906Z
---

## Install a REST-API client

Install a client to send test requests to the REST API.

- Recommended: [Postman](https://www.postman.com/downloads/) (free)
- Alternative tools: **cURL** (command-line), [Insomnia](https://insomnia.rest)

:::CodeblockTabs
Curl Example

```curl
curl -X GET "https://api.example.com/v1/data" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json"
```
:::

## Gather connection details

Before connecting, make sure you have the following details:

- **API Reference/Documentation**
  Obtain the official REST API documentation (webpage or document).
- **Request/Load Limitations**
  Check for any restrictions, e.g., 100 requests/hour.
- **Connection Details**
  - **Endpoint Address**: IP address and TCP port.
  - **Credentials** (examples below):
    - **Basic Auth**: Username & Password
    - **Identifier & Secret**
    - **Bearer Token**
    - **OAuth2 Credentials**:
      - Client ID & Client Secret, or Base64 token (identifier\:secret encoded)
      - Username & Password
      - OAuth Scope (if non-default) – defines granted privileges
    - **Custom Authentication**:
      May require development effort.

## Perform a request and get a 200 status code with data in return

- Open your REST-API client and create a new request.
- Set method & endpoint:
  - Select `GET` (or the method required by the API).
  - Enter the full enpoint.
    - **Example: **`https://api.example.com/data`
- Authentication:
  - Go to the related authentication tab.
  - Select the required auth type (Basic Auth, Bearer Token etc.).
  - Enter your credentials or token.
- Headers (if needed):
  - Add `Content-Type: application/json` or any required custom headers.
- TLS validation:
  - Enter the TLS settings.

:::hint{type="info"}
Disable `validate certificate` in your REST-API client if there are no valid TLS certificate served by the REST API (self-signed TLS certificate = invalid).
:::

- Perform a test request.
  - Expect an HTTP **200 OK** response.
  - Verify that the response body contains the data you intend to collect.

## Troubleshooting API connection

### Permission denied or 401 Unauthorized

- Could be caused by invalid credentials (expired token, wrong username/password).
  - Double-check credentials (token, username/password, client ID, client secret etc.).
  - Re-issue or refresh authentication tokens if expired.
  - Consult the API documentation for required parameters.

### Couldn't resolve host name

- Check the host name.
  - If DNS is used check if VPN is required to have access.
  - Test network reachibility: `ping` or `curl` to the endpoint.

### Rate limits exceeded (too many requests in a short time)

- Consult the API documentation for required parameters.