Create a project


Run these commands to create a new Biff project (and if you run into any problems, see Troubleshooting):

# Linux, Mac
bb -e "$(curl -s"

# Windows
iwr -out new-project.clj
bb new-project.clj

This will create a minimal CRUD app which demonstrates most of Biff's features. Run bb dev to start the app on localhost:8080. Whenever you save a file, Biff will:

  • Evaluate any changed Clojure files (and any files which depend on them)
  • Regenerate static HTML and CSS files
  • Run tests

You can connect your editor to nREPL port 7888. There's also a repl.clj file which you can use as a scratch space.

When you're ready to deploy, see Production.

Jacking in

cider-jack-in and similar commands will start up a JVM and an nREPL server for you. However, bb dev already does that. Instead of running cider-jack-in, you should run cider-connect (or the equivalent) so that you can connect to the nREPL server started by bb dev. See Connecting to a Running nREPL Server in the CIDER docs.

This does mean that CIDER will not be able to decide which version of the nREPL server dependencies to use. If you run into problems, you'll need to set the versions manually in deps.edn:

{:deps {nrepl/nrepl       {:mvn/version "..."}
        cider/cider-nrepl {:mvn/version "..."}


If you're on Windows, I recommend using Biff via WSL2. I do this myself. Plain Windows will mostly work, but the bb prod-dev command (used for Biff's optional develop-in-prod workflow) is unsupported, unless you manage to install rsync and fswatch somehow. (PRs welcome if you can figure out how to remove those dependencies.)

Have a question? Join the #biff channel on Clojurians Slack.