---
url: https://lookingglass.kloudkit.com/guide/response-formats.md
description: >-
  Pick HTML or JSON responses from Looking Glass, copy a request as JSON or raw
  HTTP, and see how bodies are capped.
---

# Response Formats

Looking Glass answers in HTML by default, for reading in a browser, and in JSON for scripts
and tests.
The format is picked by its own header, so it never collides with the request's `Accept`.

## At a Glance

* Looking Glass running *(see [Getting Started](./getting-started))*.
* The `X-Glass-Format` header, or the `format` query parameter.

## Pick a Format

```sh
# HTML (default)
curl 'localhost:8080/api/users?page=2'

# JSON
curl 'localhost:8080/api/users?page=2' -H 'X-Glass-Format: json'
```

In a browser, where you can't set headers, add `format=json` to the URL:

```text
http://localhost:8080/api/users?page=2&format=json
```

* **Header first:** `X-Glass-Format` wins over `format` when both are set.
* **Anything but `json` is HTML:** the value is case-insensitive *(`JSON` works)*, and an
  unknown value falls back to HTML.
* **The parameter is reflected:** `format` shows up in the reflected query, like any other
  parameter.

## The HTML View

The HTML view shows the request line, the time, the client address and the host, then the
query and the headers as tables, and the body.
Empty sections are left out.
The page title is the method and path, so browser tabs tell requests apart.

![The HTML view of a GitHub push webhook: the request line, its query, headers and JSON body](/screenshots/html-view.webp)

### Copy As

The **Copy as** control in the corner copies the request to your clipboard:

* **JSON:** the same document the JSON format returns.
* **Raw:** an HTTP dump of the request line, the headers and the body.

::: tip
Browsers only allow clipboard access on `https` pages and on `localhost`.
Behind plain `http` on another host, the buttons don't copy.
:::

## Bodies

Request bodies are reflected up to 1 MiB by default *(see
[Configuration](../reference/configuration))*.
Past the limit, the body is cut off: the JSON's `truncated` is `true`, and the HTML view marks
the body as truncated.

## Safe to Open

Every reflected value is escaped in the HTML view, so a request carrying HTML or script can't
run in your browser.

## Next Steps

* [JSON Response](../reference/json-response): every field of the JSON format.
* [Activity Log](./activity-log): the one-line record of each request.