Wunderground requires a key.
Developers can get a free one, if/once registered, that has daily/minute limits.

Qriusity is a quiz and trivia API.
The API is easy to use and requires no signup :)

Microsoft constantly 302's their Maps API which in turn breaks our build. Pointing the reference link to the Maps API documentation should hopefully fix some of these unnecessary failures.

This API has gone [private](https://www.patreon.com/posts/api-is-going-10743518) and now a small fee is required to use it.

According to @davemachado remark #347 re-ordering my contribution

Add France address database searching engine, `adresse.data.gouv.fr`, powered by OSS : https://github.com/addok/addok

The [Navitia](https://www.navitia.io/) API is an open API build around transport data.

you can query for journeys, isochrone, schedules, realtime data, ...

Marvel now requires an account to get an api key.

It's free for open source and free for smaller/personal/learning projects. There's a paid tier for enterprise.