Assistance with creating an LNURLw top up a bolt card with sats?

Ben from BTC Sessions has a great video where he explains how to top up a Bolt card with a lightning URL (from 13.20 at https://youtu.be/vNX2xwvh8SQ)

The Lt.pay generation website Ben uses looks like they're closed down. I'd appreciate any help on how I'd be able to recreate what Ben does in the video using a Bolt Card?

Thanks all.