Introduction to plugins

Plugins allow you to further modify your web servers beyond the options that are available in the app.

To install a plugin in the app, go to Settings > Add Plugin and choose a directory or ZIP file.

After installing a plugin, you must specifically enable it for each server you want to use it with.


Plugins aren't sandboxed, and run with the same permissions as the app. Only install a plugin if you know and trust the developer.

Community plugins

Have you made a plugin that you want to share? Open an issue on GitHubopen in new window to request that we add it to this list.

Creating a plugin

Step 1: Create a plugin manifest file

To get started, create a new folder for your plugin. In the folder, create a new file called plugin.json. Use this file to specify the name of your plugin, a unique id, any configurable options, and the name of the script file it runs.

See Plugin manifest file for a complete guide on this file.

Example plugin.json file

  "name": "My Plugin",
  "id": "myplugin",
  "script": "script.js",
  "options": [
      "id": "header",
      "name": "Add custom header",
      "description": "Enable this option to add a custom header to each response.",
      "type": "bool",
      "default": false

Step 2: Create a plugin script

Create a JavaScript file with a name that matches the value of the script option in your plugin.json file, such as script.js.

The script can have two custom functions:

  • onStart(server, options), which is called whenever the server starts and allows you to modify the server.
  • onRequest(req, res, options, preventDefault), which is called with each request and allows you modify the response or handle the request however you want.

See Plugin script for a more details, including an explanation of the arguments to these functions, and example scripts for common use cases.

Example script file

function onStart(server, options) {
  // Do nothing

function onRequest(req, res, options, preventDefault) {
  if (options.header == true) {
    res.setHeader('my-header', 'hello world');

module.exports = {onStart, onRequest};

Step 3: Install the plugin

To install a plugin in the app, go to Settings > Add Plugin and choose the directory your plugin files are located in. You can also install a plugin from a ZIP file.

Alternatively, you can manually install a plugin by adding it to the plugins directory. The name of the folder must match the id of the plugin.

Windows: C:\Users\[USERNAME]\AppData\Roaming\Simple Web Server\plugins\

macOS (Direct download): /Users/[USERNAME]/Library/Application Support/Simple Web Server/plugins/

macOS (App Store): /Users/[USERNAME]/Library/Containers/org.simplewebserver.simplewebserver/Data/Library/Application Support/Simple Web Server/plugins/

Linux: TODO


Changes to installed plugins inside the plugins directory take effect immediately. During the development of a plugin, we recommend working with files directly inside of this directory so that you don't have to reinstall the plugin after every change.

Step 4: Debug any issues

If you see an error about the plugin.json file being invalid then check to make sure that you've formatted it correctly. See Plugin manifest file for more help.

If you encounter an "Error starting plugins" error for a server, or if you receive a Plugin error error message in response to a web request, then check the logs for more error details. See Viewing logs.

If your plugin isn't working and you aren't sure why, consider adding console.log statements to your code to help debug. See Viewing logs.