Welcome to XCODX Online Compiler
Quick Start:
Ctrl+Enter Run code
Ctrl+S Save / Download
Ctrl+L Clear output
Select a language and start coding.
Clojure is a dynamic, functional, immutable-by-default Lisp dialect that compiles to JVM bytecode (Clojure), JavaScript (ClojureScript), and the .NET CLR (ClojureCLR). Created by Rich Hickey in 2007, it brings the legendary expressiveness of Lisp — code-as-data, macros, REPL-driven development — to the entire Java ecosystem. Used in production by Nubank (the world's largest neobank), Walmart, CircleCI, Funding Circle, and Cisco for high-concurrency systems where pure functions and persistent data structures pay dividends. Run any Clojure script in this online compiler — no Leiningen, no deps.edn, no JVM setup.
;; Hello World in Clojure — REPL-friendly, functional style
(defn greet [name]
(str "Hello, " name "!"))
(doseq [lang ["Python" "Rust" "Go" "Clojure"]]
(println (greet lang)))
;; Bonus: immutable transformation pipeline
(def numbers (range 1 11))
(def squared-evens
(->> numbers
(filter even?)
(map #(* % %))
(reduce +)))
(println "Sum of squared evens 1..10:" squared-evens)
;; => 220Use Clojure for high-concurrency back-end services (its persistent data structures plus STM make race conditions almost impossible), data-processing pipelines, ETL jobs, REST APIs (Ring + Compojure + Reitit), and full-stack applications (Clojure back-end plus ClojureScript front-end with Reagent or Re-frame). It's especially popular in fintech (Nubank's entire core banking platform runs on Clojure) and at any company that needs to interop with the Java ecosystem without writing Java boilerplate.
Functional-first, with all data immutable by default. Vectors, maps, sets, and lists are all persistent — changes return new versions, originals stay intact, and they share structure under the hood for performance. You can interop with Java's mutable object world when needed, but idiomatic Clojure pushes you toward pure functions and immutable values.
Clojure compiles to JVM bytecode and runs on the Java Virtual Machine. ClojureScript compiles to JavaScript and runs in the browser or Node.js. Same language, two target platforms. Reader conditionals ( #?(:clj ... :cljs ...) ) let the same .cljc file target both, which is why so many Clojure libraries publish as 'cljc' for full-stack reuse.
Clojure is a Lisp, and Lisps use parentheses as the universal syntax for both function calls and data structures. This 'code is data' homoiconicity is what enables Clojure's powerful macro system — you transform programs as if they were lists, because they are lists. Modern editors with rainbow parens, structural editing (Paredit), and tools like Calva for VS Code make the parentheses essentially invisible after the first week.
main.cljclojureread-line(println "Hello from Clojure!")
(println "Welcome to XCODX Online Compiler!")
(def message "Clojure is a Lisp!")
(println message)