Ask HN: Is it safe to use Facebook's open source projects?

Hmm, interesting. The grant of rights looks as though it's designed to build a defense against patent claims against Facebook. Get everyone using their stuff, and anyone who does will find it quite difficult to challenge Facebook patents.

IANAL, but shouldn't you be more concerned about open source projects which don't grant you patent rights required to use the software?

It is safer than using SW without those "Additional Grant of Patent Rights". They explictly state that you can use it, other didn't make the effort to check for patents, or simply can screw you later.

There is no way to be safe from patents. Anyone could have them, they don't have to declare them, and they're written in deliberately obtuse ways so that you have no way of finding relevant patents before you're sued for infringing them (you don't have to have copied, or even be aware of, any patented thing to violate a patent). It's just a hazard of the software industry.

The BSD license says nothing about patents, so this project is in some sense safer than a "normal" BSD-licensed project (but not an Apache, EPL or GPLv3-licensed project). The grant Facebook is giving you is fairly minimal but that's understandable from their perspective: they don't want to give you any extra patent rights, just enough to use the stuff they're actually trying to release.

It's not safe to use software in a commercial project. Facebook might hold patents on any random library you're using. Companies that aren't Facebook might hold patents on any random library or on React. You could develop a library in-house in a clean room and it could still infringe someone else's patent. Patents really suck that way. But React is in no more danger than any other code you might use.

EDIT: no more danger than any other BSD-licensed code. It would be safer to use code that has a less revocable patent grant, such as that in the Apache License, EPL, or GPLv3.

Of course it is – you've got this back to front. The grant of additional rights to use any patent Facebook may hold is an additional benefit and in no way places any restriction on you.

If you're going to worry about anything, worry about the squillions of open-source projects that don't include any patent grants. But you probably shouldn't worry about that either.