I developed a simple tool for decoding data from EU Green Pass QR Code.
I used Python with Flask and deployed my app using Heroku.
You just need to attach your certificate to immediately get a complete reading of the QR code.
Also in this case, no data will be stored and that if you want, since the code is open source, you can create your instance without any worries.
If you're a bit curious let's try the app in action here:
My Github project: