# Echo Endpoint Configuration

> Learn how to configure the Echo endpoint in KrakenD. A straightforward way to test your API Gateway setup containing the details of a request.

Source: https://www.krakend.io/docs/enterprise/endpoints/echo-endpoint/

The `/__echo/` endpoint is a developer tool to help you debug configurations. It works similarly to the [`/__debug/` endpoint](https://www.krakend.io/docs/enterprise/endpoints/debug-endpoint/), but instead of printing the requests in the log and returning a `{"message": "pong"}`, they are printed in the response. It replies with an object containing all the request details, and you can use it as an endpoint or backend. As KrakenD has a [zero-trust](https://www.krakend.io/docs/enterprise/design/zero-trust/) approach, you will find out the exact information that passes through in this endpoint.

Ends in slash!

Notice that the `/__echo/` endpoint has two slashes in its definition.

## Configuration

To enable the `/__echo/` endpoint, you should add in the configuration (service level) the flag `echo_endpoint`, and then use it directly by calling `http://krakend:8080/__echo/` or by adding it as a `backend` in any endpoint.

##### Echo endpoint

\* required fields

##### [`echo_endpoint`](https://www.krakend.io/docs/enterprise/endpoints/echo-endpoint/#echo_endpoint "Click to copy link to echo_endpoint") boolean

Enables the `/__echo/` endpoint for this configuration, that returns information about the incoming request. When using /\_\_echo as a backend you can check the actual headers and content a backend receives after all the zero-trust filtering.

Defaults to `false`

Schema: [https://www.krakend.io/schema/v3.0/krakend.json](https://www.krakend.io/schema/v3.0/krakend.json "JSON schema definition")

When used as a backend, you have a **fake backend** that is very useful for seeing the interaction between the gateway and the backends and testing all sorts of KrakenD components.

### Response fields

Given a request following the format `[scheme:][//[userinfo@]host][/]path[?query][#fragment]`, the `/__echo/` endpoint will answer with the following structure:

```json
{
  "req_uri": "/__echo/foo/bar/vaz?q=foo#fragment",
  "req_uri_details": {
    "user": "userinfo",
    "host": "krakend:8080",
    "path": "/__echo/foo/bar/vaz",
    "query": "?q=foo",
    "fragment": "fragment"
  },
  "req_method": "POST",
  "req_querystring": {
     "q": ["foo"]
  },
  "req_body": {
     "@comment": "The correct parsing of the body is not guaranteed as its content is unknown (and even binary)"
  },
  "req_headers": {
     "Content-Type": ["application/json"]
  }
}
```

## Echo endpoint example

The most beneficial case is when you add KrakenD itself as another backend using the `/__echo/` endpoint. Then, you can see exactly what headers and query string parameters your backends receive in the responses.

To test it, save the content of this file in a `krakend.json` and start the server:

```json
{
  "version": 4,
  "port": 8080,
  "echo_endpoint": true,
  "endpoints": [
    {
      "endpoint": "/test/{var}",
      "backend": [
        {
          "host": ["http://127.0.0.1:8080"],
          "url_pattern": "/__echo/{var}"
        }
      ]
    }
  ]
}
```

**Default behavior:**

Ignore query strings by default 

```
$curl -i -H'Test: foo' 'http://localhost:8080/test/one?a=1&b=2&c=3'
```

In the response, you will see that `a`, `b`, and `c` do not appear, neither the sent headers. The `curl` command automatically sends the `Accept` and `User-Agent` headers, but they are not in the backend call either. Instead, you see the KrakenD User-Agent as set by the gateway.

Play now with the [parameter forwarding](https://www.krakend.io/docs/enterprise/endpoints/parameter-forwarding/), such as the `input_headers` and `input_query_strings`, and repeat the test.