Balancer V2 Stable Pools
This package contains the source code of Balancer V2 Stable Pools, that is, Pools for tokens that all have values very close to each other (typically stablecoins).
The flavors currently in existence are StablePool (basic five token version) and MetaStablePool (two token version for assets with externally-provided known exchange rates, plus a price oracle).
Another useful contract is StableMath, which implements the low level calculations required for swaps, joins and exits.