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CIDER is the Clojure(Script) Interactive Development Environment that Rocks!

CIDER extends Emacs with support for interactive programming in Clojure. The features are centered around cider-mode, an Emacs minor-mode that complements clojure-mode and clojure-ts-mode. While clojure-mode and clojure-ts-mode support editing Clojure source files, cider-mode adds support for interacting with a running Clojure process for compilation, code completion, debugging, definition and documentation lookup, running tests and so on.

OpenCollective OpenCollective Patreon Paypal

Bozhidar (a.k.a. Bug, CIDER's primary author/maintainer) has spent countless hours working on CIDER and the numerous related projects. That's a lot of work and not all of it is fun!

Please consider supporting financially CIDER's ongoing development.


The instructions that follow are meant to get you from zero to a running CIDER REPL in under 5 minutes. See the online documentation for (way) more details.



The recommended way to install CIDER is via package.el - the built-in package manager in Emacs.

CIDER is available on all major package.el community maintained repos - NonGNU ELPA, MELPA Stable and MELPA.

Provided you've enabled one of them in your Emacs setup, you can install CIDER with the following command:

M-x package-install RET cider RET

Launch an nREPL server and client from Emacs

Simply open in Emacs a file belonging to your lein, tools.deps or boot project (like foo.clj) and type M-x cider-jack-in. This will start an nREPL server with all the project dependencies loaded in and CIDER will automatically connect to it.

Alternatively you can use C-u M-x cider-jack-in to specify the path to a Clojure project, without having to visit any file in it.

Tip: In Clojure(Script) buffers the command cider-jack-in is bound to C-c C-x (C-)j.

Connect to a running nREPL server

You can go to your project's directory in a terminal and type there (assuming you're using Leiningen that is):

$ lein repl

Or with Boot:

$ boot repl -s wait

Alternatively you can start nREPL either manually or by the facilities provided by your project's build tool (tools.deps, Gradle, Maven, etc).

After you get your nREPL server running go back to Emacs. Typing there M-x cider-connect will allow you to connect to the running nREPL server.

Tip: In Clojure(Script) buffers the command cider-connect is bound to C-c C-x (C-)c (C-)j and the command cider-connect-cljs is bound to C-c C-x (C-)c (C-)s.

Diving Deeper

CIDER packs a ton of functionality and you really want to be familiar with it, so you can fully empower your workflow. The best way to get acquainted with all available features is to go over the entire CIDER manual.

If you're into video lessons, you might also check out this intro to CIDER demo as well.

Quick Reference Card

You'll find all of CIDER's essential commands and their keybindings in its one-page printable quick reference card.

New CIDER users might benefit from keeping a copy close to their keyboard.

Get Help

Start with CIDER's discussions board. If it doesn't get the job done consider some of the other available support channels.


An extensive changelog is available here.


The Core Team

The direction of the project is being stewarded by the CIDER core team. This group of long-term contributors manage releases, evaluate pull-requests, and does a lot of the groundwork on major new features.

CIDER Alumni

In addition, we'd like to extend a special thanks the following retired CIDER core team members. Lovingly known as The Alumni:

Release policy

We’re following SemVer.

You can read more on the subject here.


CIDER's logo was created by @tapeinosyne. You can find the logo in various formats here.

The logo is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.


CIDER's homepage is in the gh-pages branch of this repository and is deployed automatically when changes are made to it.

It's just a single index.html file and a bit of Bootstrap 4. Contributions to it are very welcome!


While CIDER is free software and will always be, the project would benefit immensely from some funding. Raising a monthly budget of a couple of thousand dollars would make it possible to pay people to work on certain complex features, fund other development related stuff (e.g. hardware, conference trips) and so on. Raising a monthly budget of over $5000 would open the possibility of someone working full-time on the project which would speed up the pace of development significantly.

We welcome both individual and corporate sponsors! We also offer a wide array of funding channels to account for your preferences (although currently Open Collective is our preferred funding platform).

If you're working in a company that's making significant use of CIDER we'd appreciate it if you suggest to your company to become a CIDER sponsor.

You can support the development of CIDER, clojure-mode and inf-clojure via Open Collective, GitHub Sponsors, Patreon and PayPal.

Open Collective Backers

Open Collective Sponsors

Become a sponsor and get your logo on our README on Github with a link to your site. [Become a sponsor]


CIDER is distributed under the GNU General Public License, version 3.

Copyright © 2012-2024 Bozhidar Batsov, Artur Malabarba, Tim King, Phil Hagelberg and contributors.