A lot of new sources of free, public data have emerged over the last few years, and this guide covers some of the most useful. It’s aimed at developers looking for information to supplement their own tools or services. There are obviously a lot of APIs out there, so to narrow it down to the most useful, the ones in this guide have to meet these standards:
Traditional commercial data agreements are designed for enterprise companies, so they’re very costly and time-consuming to experiment with. APIs that are either free or have a simple sign-up process make it a lot easier to get started.
Quite a few startups build infrastructure and then hope that users will populate it with data. Most of the time, this doesn’t happen, so you end up with APIs that look promising on the surface but actually contain very little useful data.
Most of us now develop in the web world, so anything else requires a complex installation process that makes it much harder to try out.
There has to be some way to look up information that ties the service’s data to the outside world. For example, the Twitter and Facebook APIs don’t qualify because you can only find users by internal identifiers, whereas LinkedIn does because you can look up accounts by their real-world names and locations.
I also avoid services that impose excessive conditions on what you can do with the information they provide. There are ...