Are these code tools built using https://github.com/kythe/kythe ? Any other OSS projects by Google that back these?

Piper was actually a big source of frustration for me. Yeah it's dead simple, but once you have a CL chain, you're entering a world of pain. I've switched to Fig a while ago and haven't looked back. Beyond a tiny fix I'll start editing from CS or a throwaway citc client, it's just simpler to use fig. I've been able to juggle 4-5 CL chains easily and it makes my workflow much easier. Also splitting CLs before review is much simpler with Fig.

:) https://github.com/jhuangtw-dev/xg2xg

In my opinion, what makes them really great is the tight integration that they have. For example, since the whole company uses one build system and one single repository, you can build a truly awesome IDE that knows about every library in the company and can autocomplete for it. Same for code search, where cross references are accurate and work cross languages (for example a class generated from Protobuf).

So CodeSearch, Critique, Borg, Sherlog, Cider come to mind as top notch tools that are not available outside. As far as libraries go, the C++ Fibers thing is incredible and I don't think it's open.

Blaze is amazing (albeit a bit slow) but Bazel should be more or less the same, haven't used it. Dremel, Spanner, Tensorflow, Proto, grpc are all available outside. Abseil (https://abseil.io/) is a great library available to everyone.