If you want to get started with developing Trello Power-ups, GitHub Pages allows you to host your Power-Up for free (provided you're fine with making your repository public).
You can take a look at how it works with Trello's template.
Unfortunately, GitHub Pages doesn't let you have a development branch that pushes to a separate URL, so there's a couple of options for testing:
In this post we're going to be exploring the third option.
Install github-pages using
gem install github-pages.
If you don't have ruby installed, you can follow the instructions here.
You can then run your Power-Up locally using
This will make it available to you at
You'll need to download ngrok to create a tunnel between your locally hosted Power-Up and the internet.
Once you've got it downloaded, run
jekyll serve in one terminal window, and then
./ngrok http 4000 in another.
This will give you a ngrok URL, which will look something like
https://12345abc.ngrok.io (make sure you choose the https url!)
Paste this URL straight into your Power-Up settings and voila!
If everything looks good, you'll want to push your local changes to your repository. But before you do, make sure you've added the following lines to your .gitignore:
Gemfile Gemfile.lock _site/
This prevents any Jekyll-related files from being pushed up to your remote repository.
This approach is great if you want to do all of your development in the same place, without having to worry about new repositories or Glitch projects. The one downside is that due to ngrok, the initial page load of your Power-Up is a lot slower, so keep that in mind!