Abseil
Google's general-purpose C++ libraries that extend the standard library
What it is
Abseil is a collection of C++17 library code drawn from Google's internal codebase, covering strings, Swiss-table hash containers, status and error types, logging, command-line flags, time and time zones, synchronization, random numbers, and 128-bit integers. Some pieces fill gaps in the standard library while others offer alternatives tuned for specific needs. C++ developers add it to projects built with Bazel or CMake to get tested building blocks, with long-term support releases available for teams that cannot track the latest commit.