nREPL is a Clojure network REPL that provides a REPL server and client, along with some common APIs of use to IDEs and other tools that may need to evaluate Clojure code in remote environments.

nREPL powers many well-known development tools.

• Start an nREPL server (e.g. with lein repl)
• Connect to the server using any nREPL client (e.g. CIDER, Calva, vim-fireplace, rebel-readline)
• Start hacking!

See the documentation for way more information on the subject.

You can find nREPL's API documentation on cljdoc.

Extremely stable. nREPL's protocol and API are rock-solid and battle tested. nREPL's team pledges to evolve them only in backwards-compatible ways.

All experimental features are marked explicitly as such in nREPL's documentation, but even those are fairly stable by most standards.

Check the brief history of nREPL, available here.

Check out this detailed comparison.

Yes and no. The reference nREPL implementation is Clojure-specific, but it can be extended with ClojureScript support via the Piggieback middleware. In the future there may be implementations of nREPL that target ClojureScript directly.

The nREPL protocol is language-agnostic and implementations of nREPL servers exist for several programming languages. Implementing new nREPL servers is pretty simple.

See Hacking on nREPL.

This project exists thanks to all the people who contribute.

Thank you to all our backers! 🙏 [Become a backer]

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Copyright © 2010-2025 Chas Emerick, Bozhidar Batsov and contributors.

Licensed under the EPL. (See the file epl.html.)