File serving

Besides using the body editor, Mockoon allows you to serve different files for each route. File serving should be the preferred method when you want to send lots of data.

 Using files

To serve a file, you must provide a path in the file input field:

fill the file input field

 Absolute or relative paths

You can either provide an absolute path like /home/username/file.json or a relative path. Starting with v1.16.0, relative paths are resolved from the environment's file location. You can check the environment's file location by right-clicking on an environment en select "Show in folder" in the contextual menu:

show in folder menu entry


Templating is available in both the file content and the file input field.

 File content templating

As for the body editor, templating will be parsed inside files for a limited set of MIME types (application/json, text/html, text/css, text/csv, application/javascript, application/typescript, text/plain, application/xhtml+xml, application/xml). You can use all the available templating helpers to generate dynamic mock data.

Templating can be disabled both for the body editor and the file content. Please refer to the templating documentation for more information.

 File input templating

Templating is also supported directly in the file input field. It allows to dynamically generate the file path using helpers. Please refer to the templating documentation for more information.

 404 fallback

By default, Mockoon will return an error in the body when a file is not found. It will still keep the status code you set up on your route response. You can instead choose to automatically return a 404 by activating an option in the route response settings:

tick the 404 fallback checkbox

This option will also fall back to use the content present in the body editor.

 Serving a range of bytes from a file

Mockoon supports the Range header for files that are not parsed by the templating engine or when the templating is disabled on the response (see above).

To use this feature, you must provide a Range header in your request. The header value must be in the form bytes=start-end where start and end are the byte positions of the file you want to return. For example, bytes=0-100 will return the first 100 bytes of the file.

The server will answer with a 206 Partial Content status code and the Content-Range header containing the range of bytes returned. If the range is invalid, the server will answer with a 416 Range Not Satisfiable status code.