Wide-Integer implements a generic C++ template for uint128_t, uint256_t, uint512_t, uint1024_t, etc.

Extended precision integer C++ library

C++ implementation of wide exact-width integer types

Arbitrary-precison integers library in c++. It handles signed integers of any size and any base between 2 and 16. It also hande operations between different bases.

An unsigned 256 bit integer type for C++