All official nREPL extensions (e.g. Piggieback and Drawbridge) share the same license.
While nREPL was part of Clojure Contrib (until 2018), it was also licensed under Clojure’s Contributor Agreement,
but this was changed with nREPL 0.3. You can find the re-licensing discussion here.
Copyright © 2010-2021 Chas Emerick, Bozhidar Batsov and nREPL contributors.