The initial version, released in 2010, was based on Apache Thrift and it predated Finagle, their building block for RPC services at Twitter. The Snowflake they're using internally is a full rewrite and heavily relies on existing infrastructure at Twitter to run.
This reminds me a little bit of Twitter's snowflake: To generate the roughly-sorted 64 bit ids in an uncoordinated manner, we settled on a composition of: timestamp, worker number and sequence number.
Sequence numbers are per-thread and worker numbers are chosen at startup via zookeeper (though that’s overridable via a config file).
Interesting... on 2022-12-13 the bounty has been claimed! Just a few hours after mprime1 shared the project in a comment on HackerNews, someone managed to drain the BTC.
(Now my hand hurts...)