Adding an app to the Bangle.js App Loader

If you have an app (eg by following the Bangle.js First App tutorial), you might want to add it to the Bangle.js App Loader so you or others can easily install it.

Note: To keep things simple for everyone, the BangleApps Git repository and all code in it are MIT Licensed. By contributing an app you're agreeing that the code in it will be MIT Licensed too, and you need to be sure you don't include any copyrighted code data or images that you don't have the right to distribute freely.


The first step is to 'Fork' the existing Bangle.js App Loader (make your own copy).

Enable GitHub Pages

Now, let's enable "GitHub Pages", which allows you to view and use your own copy of the repository.

  • Click Settings up the top right of the repository page
  • On the left panel, select Pages
  • Under Source, choose master branch
  • Now click Save
  • The page will refresh and under GitHub Pages it'll then say:
Your site is ready to be published at

Note: You can host the App Loader yourself, but it must be on an HTTPS server (not HTTP) for Web Bluetooth to work.

Adding your app

If you followed the Bangle.js First App tutorial you should now have an app with an ID of timer, so let's use that. We should create a new folder of the same name as your app's ID in the apps folder.

An example of what the folder might look like is in:

Note: If you just want to add a feature to an existing app, please consider modifying that app (see Making Changes below) rather than copying the app to a new one and making your change. Almost identical copies of the same app mean that if a bug is discovered in one app, someone has to manually copy the fixes over to each copy.

Experienced Git developers will know about cloning a repository to their local computer, but I'll assume you don't know/want to do that, so we'll do everything online.

  • Go to your BangleApps repository at
  • Click on the apps folder
  • Click the Create new file button
  • Now type timer/app.js in the name box and copy/paste your app's JavaScript into the editor box. If you don't have anything and want to try it out, just add:
E.showMessage("My\nSimple\nApp","My App")
  • Now click the Commit new file button
  • The window will now be in the BangleApps/apps/timer folder, and we now want to add the app icon.
  • In Bangle.js First App we downloaded a 48px icon as a PNG file, so let's use that.
  • Rename the file on your computer to app.js (GitHub doesn't provide a way to rename files)
  • Click Upload files in GitHub's BangleApps/apps/timer folder, upload the file, and click Commit Changes

Now we need to upload the icon in a form that Bangle.js understands

  • Go to
  • Click Choose File and upload the app.png file
  • Check Use Compression and Transparency
  • If your image is in color, change Colors to 3 bit RGB and check the preview image. If it doesn't look good choose Optimal 2/3/4 bit instead - the higher the number the more colors but the more space the image takes up.
  • Under Output As choose Image String
  • Now you'll see some text like var img = E.toArrayBuffer(atob("...")). Highlight and copy just the E.toArrayBuffer(atob("...")) part - do not copy var img =
  • Go back to GitHub and the BangleApps/apps/timer and create a new file called app-icon.js with the E.toArrayBuffer(atob("...")) code you just copied in it, and click Commit new file

At this point you could add a ChangeLog file so others can see what changed if you release multiple versions of your app, but we're going to skip that for now.

Finally, it's time to add a description of your app. There's an example at

  • Click on the file metadata.json
  • Click on the little pencil 'edit' icon in the top right
  • Now edit the file to contain:
{ "id": "timer",
  "name": "My Timer App",
  "shortName":"My Timer",
  "icon": "app.png",
  "description": "This is a description of my awesome timer app",
  "tags": "",
  "supports": ["BANGLEJS2"],
  "storage": [

Note: we're assuming you're writing and app for Bangle.js here. If you're writing for Bangle.js 1 use "supports": ["BANGLEJS"], instead, or for both, use "supports": ["BANGLEJS","BANGLEJS2"],

There is more information about the format of the metadata.json file on

  • Now click Commit Changes and you're done!

Note: If you were working with a local copy of the GitHub repository you could run the bin/sanitycheck.js file which would give your app's description a quick check over to make sure everything looked ok (icons, code, etc).

Using your new App

  • Go back to your personally hosted BangleApps repo at (make sure to hit 'reload' - you may also need to wait a minute or two for GitHub to propagate your changes).
  • You'll see an app called My Timer App - click the Upload button next to it
  • You can now press the button on your Bangle.js, open the Launcher, and see your app in there!

Note: If the App Loader doesn't work, it's almost certainly because of an error in the metadata.json file that was changed earlier.

Documenting your App

While there's short field for a description, many apps may need slightly more documentation about how to use them.

To add this documentation in a way that can be found easily from the app loader, create a file called (a markdown file) in your app's folder.

Then, in your app's metadata.json file, add:


Now, when anyone sees your app in the App Loader, there'll be a link saying Read more.... When clicked, it'll bring up a window showing your documentation.

Making Changes

If you want to change your app you can simply edit the files in your repository. However if you are publicly submitting your app we'd suggest that you add a ChangeLog file so users can see what has changed.

  • Add a file called BangleApps/apps/timer/ChangeLog - it should look like:
0.01: New App!
0.02: Fixed thingybob
0.03: Added fancy text
  • Edit metadata.json and change the line "version":"0.01", in your app to match the last number in the ChangeLog.

After this, if a user clicks on the version number in the App Loader they'll be able to see the ChangeLog file

Submitting your App to the main App Loader website

Now you have a working app it's easy to submit it.

While we will try to accept any apps you send us, we won't be able to accept any obviously broken or non-child-friendly apps. However your apps will still be available on for anyone that wants to upload them

  • In (the main repository) click Pull request up the top right
  • Scroll down and see exactly which files are set to be changed or added and make sure it looks ok.
  • If it is, click Create Pull Request
  • In the next page, write a short title and description so we can check up on your app
  • Click Create pull request

You'll see the pull request as well as yellow test saying Some checks haven’t completed yet.

We run the bin/sanitycheck.js script on any submissions using Travis CI. This allows us to do a quick check that everything is ok. It won't detect bugs in your app but it will ensure that the App Loader stays working.

After a while it'll change to either a green All checks have passed or a red Checks failed. If checks fail then we're unlikely to be able to merge as-is, but you can click Show all Checks, Details and see what errors were found. If you correct these in your repository then the check status will update.

More Info

There are a more Bangle.js tutorials on making apps.

For a reference of the format of apps and the JSON, check out the Bangle.js App Loader's README file

Maintainers of the espruino/BangleApps repository use the App Contribution checklist as an aid when reviewing pull requests.

This page is auto-generated from GitHub. If you see any mistakes or have suggestions, please let us know.