Not to excuse these dark patterns from shitty products that can't get revenue without tricking people, but privacy.com lets you set up single-use credit cards with e.g. a $1 lifetime limit. This is my go-to for places like this if I really, really want to try it.

FWIW I’ve been using brainfm for about 8 years.

Granted, I got my account with a lifetime subscription back when they were just spinning up, but I’ve used them pretty consistently since then.

it's worth it, good product

You might enjoy the binaural beats and ambient radio on https://ambiph.one as a free alternative (disclosure: it's my site). Not as science-y as brain.fm but it helps me a lot with focus

Wow - nice work! Your site looks and works great. Thanks for sharing it.

Thanks, glad you like it! I'm all ears if you have any suggestions (here or there's a feedback form linked at the bottom)

You have created a fantastic site. Endless combinations.