FWIS3

Have fun with it!
I did.

Does gifs:
https://kazuhikoarase.github.io/qrcode-generator/

Does png files but can write longer text.
https://www.the-qrcode-generator.com/

Does jpeg and long text
http://www.qr-code-generator.com/

And my cheap Chinese Android phone can scan them

Congratulations. You now do what I've been doing on my posters for conferences for years. (Namely, put a QR code in the corner that goes to either a pdf of the poster or the group website with a list of publications. Quite handy!)