Are there any open APIs left?

One of the dreams of Web 2.0 was that website would speak unto website. An "Application Programming Interface" (API) would give programmatic access to structured data, allowing services to seamlessly integrate content from each other. Users would be able to quickly grab data from multiple sources and use them for their own purposes. No registration or API keys, no tedious EULAs or meetings. Just pure synergy!

Is that dream dead? If so, what killed it?

A decade ago, I posted a plea looking for Easy APIs Without Authentication with a follow up post two years later. I wanted some resources that students could use with minimal fuss. Are any of the APIs from 10 years ago still alive?

Alive

These ones are still around:

• Wikipedia - Yes! Still going strong.
• Police.uk - Yes! After a brief dalliance with API registration, it is now back to being completely free and open.
• Google Books ISBN - Yes! Obviously Google have forgotten it exists; otherwise it would have been killed off by now!
• iTunes Lookup - Yes! Possibly the only thing Apple don't charge a premium for.
• Pokémon API - and still receiving frequent updates.
• MusicBrainz - this Internet stalwart will never die.
• Open Notify - a collection of space APIs, although the code hasn't been updated in ages.

Dead

These have shuffled off this mortal coil:

• BBC Radio 1 - No.
• Twitter URL statistics - LOLSOB No.
• Star Wars API - No.
• British National Bibliography - No. Dead due, I think to the British Library's cyber attack.
• Football Data - gone.

API Key Required

These are still alive, but you either need to pay or register to use them:

• Google Location
• Spotify
• OpenMovieDB
• Open Air Quality

What Happened?

Something something … enshittification … blah blah … zero interest rate phenomenon … yadda yadda our incredible journey …

But back in the land of rationality, I've had a lots of experiences running APIs and helping people who run them. The closure and lockdown of APIs usually comes down to one or more of the following.

APIs cost money to run. Yes, even the static ones have a non-zero cost. That's fine if you're prepared to endless subsidise them - but it is hard to justify if there's no return on investment. Anyway, who is using all this bandwidth? Which leads on to:

Lack of analytics. Yes, I know tracking is the devil, but it is hard to build a service if you don't know who is using it. Sure, you can see traffic, but you can't tell if it is useful to the end consumer, or what value you can share. There's no way to communicate with an anonymous consumer. Which, of course, takes us to the next barrier:

Communication is key. If you need to change your API, there's no way to tell users that a change is coming. That might be the announcement of a deprecation, an outage, or an enhancement. You can try smuggling error messages into your responses and hoping someone notices a failing service somewhere - but it's much easier to email everyone who has an API key. And you know what else keys are good for?

Stopping abuse. It'd be nice if everyone played nice online; but some people are raging arseholes. Being able to throttle bad actors (figuratively or literally) is a desirable feature. On a resource constrained service, you sometimes have to put rules in place.

Still, if you know of any good open APIs which don't require registration, and that you think will survive until 2036, please drop a link in the comments.