https://www.ifixit.com/ - free repair guides

https://www.erowid.org/ with plenty of resources for harm reduction. In case you or a loved one is a drug user, at least you can help them (or yourself) to not hurt them too much

squoosh.app - Easy to use image compression without upload

Can I offer a non tech site?

https://www.seat61.com/

A bit niche - train travel around the world - but if you want to travel between countries by train, or several countries, or cross country, this is THE site. I’ve used it for inspiration, and for checking whether a mad idea I’ve had is feasible, and for planning.

I’ve done a few trips by train and often people are amazed at my travel know-how but in reality I have none, the guy who makes this website does, and he makes it all incredibly easy. Timetables, prices, options, suggested routes, links to buy tickets, what to expect from the train facilities, it’s all in there.

The fediverse

Saltify Share sensitive information safely

• SourceHut as an alternative git foundry, https://sr.ht
• Any HedgeDoc deployment , like https://pad.nixnet.services/
• Any jitsi meet deployment, like https://meet.jit.si/
• KeyOxide for online identity verification (using gpg), https://keyoxide.org/
• PlantUML for drawing all kinds of diagrams based on formal text descriptions (online version: https://www.plantuml.com/plantuml/uml/, but mainly just an offline tool). I’d encourage people not to use online services for everything but simply rely on good tools.
• Freesound.org (https//freesound.org) for sound fragments
  • TrekCore.com for Star Trek sounds ;) https://www.trekcore.com/audio/
• Bookwyrm as a fediverse alternative for sites like goodreads (tracking and reviewing books): https://bookwyrm.social/
• Fotostrips.nl if you’re dutch and like comics

And in general I’d wish more people would use RSS (and more sites would prominently offer it) to aggregate things like news.

wavedrom.com is something I myself discovered recently. It can draw timing diagrams by taking JSON-style text as input.

Sleepytime.cc. It calculates sleep cycles to tell you when to go to sleep or when to wake up. I’ve been using it for years and can attest that I always wake up feeling rested and refreshed.