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KLIPSE is a simple client-side code evaluator pluggable on any web page.


The klipse plugin is a javascript tag (see details below) that transforms static code snippets of an html page into live and interactive snippets:

  1. Live: The code is executed in your browser
  2. Interactive: You can modify the code and it is evaluated as you type

The code evaluation is done in the browser: no server is involved at all!

Live demo

With the klipse plugin, the code is evaluated as you type...

Here is a live demo of the embedding of klipse in a web page.

Javascript Ruby
abc abc
PHP Clojure
abc abc

Supported languages

The code editing inside the interactive snippets is powered by CodeMirror.

How does it work?


In order to integrate the klipse plugin on a blog, library documentation or any other web page, you have to follow 3 simple steps.

  1. Make sure you have <!DOCTYPE html> at the top of your html file and <meta charset="utf-8"> right after your <head> (It is required in order to display properly the CodeMirror elements used by Klipse.)

  2. Add css and custom configuration somewhere in the page (it could be in the <head> or in the <body>) before the <script> element of step #3. The selector keys are per language (see below for a list of supported languages) and the value are the CSS selector of the elements that you want to klipsify.

<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector_eval_js: '.language-klipse-eval-js', // css selector for the html elements you want to klipsify 
  1. Add the javascript library at the end of the body tag :
    <script src=""></script> 

Here is an interactive guide of the klipse snippets.

If you want to host the javascript tag from your own server, see Host Klipse Locally.

If you want to use an older version of Klipse, see Use Older Versions.


Here is the full interactive guide of the klipse javascript snippets.

<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector_eval_js: '.language-klipse-eval-js', // css selector for the html elements you want to klipsify 
<script src=""></script>

Here is a jsfiddle with the klipse plugin for javascript. And here are detailed explanations about a javascript live code editor in a blog post.


Pay attention: for clojure interactive snippets, you must use the non-minified version of klipse as for the moment, self-host cljs doesn't support advanced compilation!

Here is the full interactive guide of the klipse clojure snippets.

You can manipulate the DOM inside KLIPSE: here is a tutorial.

<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector: '.language-klipse'// css selector for the html elements you want to klipsify 
<script src=""></script>


<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector_eval_python_client: '.language-klipse-python', // css selector for the html elements you want to klipsify 
<script src=""></script>


<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector_eval_ruby: '.language-klipse-eval-ruby', // css selector for the html elements you want to klipsify 
<script src=""></script>


<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector_eval_scheme: '.language-klipse-eval-scheme', // css selector for the html elements you want to klipsify 
<script src=""></script>


<link rel="stylesheet" type="text/css" href="">
    window.klipse_settings = {
        selector_eval_php: '.language-klipse-eval-php', // css selector for the html elements you want to klipsify 
<script src=""></script>


If your site runs under https, you need to load the klipse plugin from instead of

The reason is that the klipse plugin is hosted on Google Cloud Storage and for the moment SSL is not supported for custom domains.


The klipse plugin is configurable both at the level of the page and at the level of the snippet.

Page level configuration

Here are the settings for the klipse plugin a page level:

window.klipse_settings = {
          eval_idle_msec: 20, // idle time in msec before the snippet is evaluated 
          selector: '.language-klipse', //selector for clojure evaluation snippets 
          selector_js: '.language-klipse-js', // selector for clojure transpilation snippets  
          selector_reagent: '.language-reagent', // selector for reagent snippets 
          selector_google_charts: '.language-google-charts' // selector for google charts snippets 
          selector_oblivion: '.language-oblivion' // selector for oblivion snippets 
          selector_eval_js: '.language-klipse-eval-js', // selector for javascript evaluation snippets 
          selector_eval_ruby: '.language-klipse-eval-ruby', //selector for ruby evaluation snippets 
          selector_es2017: '.language-klipse-es2017', // selector for EcmaScript 2017 evaluation snippets 
          selector_jsx: '.language-klipse-jsx', // selector for jsx evaluation snippets 
          selector_transpile_jsx: '.language-transpile-jsx', // selector for jsx transpilation snippets 
          selector_render_jsx: '.language-render-jsx', // selector for jsx rendering snippets    
          selector_react: '.language-react', //selector for react snippets 
          selector_eval_php: '.language-klipse-eval-php', // selector for php evaluation snippets 
          selector_eval_markdown: '.language-klipse-markdown', // selector for markdown transpilation snippets 
          selector_eval_lambdaway: '.language-klipse-lambdaway', // selector for lambdaway transpilation snippets 
          selector_eval_python_client: '.language-klipse-python', // selector for python evaluation snippets 
          selector_eval_cpp: '.language-klipse-cpp', // selector for cpp evaluation 
          selector_eval_html: '.language-klipse-html', // selector for html evaluation snippets 
          selector_sql: '.language-klipse-sql', // selector for sqlite evaluation snippets 
          selector_eval_scheme: '.language-klipse-scheme', // selector for scheme evaluation snippets 
      selector_brainfuck: '.language-klipse-brainfuck',
      secured_eval: true/false, //secured mode (default: false) 
      cached_ns_root: '/my-root', // the root of clojure cached namespace 
      clojure_cached_macro_ns_regexp: /reagent.*/, // the regexp for clojure macro namespaces that are cached 
      clojure_cached_ns_regexp: /reagent.*/, // the regexp for clojure namespaces that are cached 
      codemirror_root: '/my-codemirror-root', // the root of codemirror files 
      scripts_root: '/my-scripts-root', // the root of scripts files (e.g pretty_format.js, opal.js ...) 

Additionaly, you can configure CodeMirror input (snippet source code) and output (snippet evaluation) by setting codemirror_options_in and codemirror_options_out:

Currently, we support all the settings CodeMirror Configuration settings and part of the Addons settings: matchBrackets and autoCloseBrackets.

For instance, you can modify the indentUnit, lineWrapping, lineNumbers and autoCloseBrackets like this:

window.klipse_settings = {
    codemirror_options_in: {
        indentUnit: 8,
        lineWrapping: true,
        lineNumbers: true,
        autoCloseBrackets: true
    codemirror_options_out: {
        lineWrapping: true,
        lineNumbers: true

Secured mode

Learn mode about Klipse secured mode.

Clojure only

  • print_length: (default 1000) max number of items in collections to display - useful to prevent browser stuck when evaluating infinite sequences like (range)
  • beautify_strings: (default false) when evaluation result is a string - display the "interior" of the string without escaping the quotes.

Snippet level configuration

The following attributes can be added to the DOM element of the snippet:

  • data-eval-idle-msec: (default 20) idle time in msec before the snippet is evaluated
  • data-loop-msec: (default undefined) the code is run in a loop every data-loop-msec msec
  • data-preamble: (default "") A string containing Clojurescript source code that should be run before the contents of this snippet, eg "(reset! canvas-id :canvas-2)". Useful for hiding implementation details from readers in blog posts, like e.g. setting a canvas-id atom to :canvas-2, or for performing any other setup operations that need to be done on a per-snippet basis.

Javascript only

  • data-external-libs: comma separated list of javascript libraries to load before snippet evaluation
  • data-async-code: (default false) when true, asynchronous calls to console.log append their result to the result cell

Clojure only

Here is a live demo of the different snippet level configuration options.

The following data attributes are supported on a klipse snippet DOM element:

  • data-static-fns: (default false) set to true for using static dispatch
  • data-external-libs: comma separated list of github repositories to resolve dependencies: you need to provide the full list of dependencies (including the dependencies of dependencies recursively). See for instance Lambda Caclulus with clojure and Klipse
  • data-print-length: (default 1000) max number of items in collections to display - useful to prevent browser stuck when evaluating infinite sequences like (range)
  • data-beautify-strings: (default false) when evaluation result is a string - display the "interior" of the string without escaping the quotes.
  • data-verbose: (default false) passed to boostrapped eval and compile :verbose opts
  • data-max-eval-duration: (default 1000) max number of milliseconds the snippet code is allowed to run synchronously before being interrupted.
  • data-compile-display-guard: (default false) when true, display the anti-starvation code inside result of compilation


The Klipse plugin can be easily styled with CSS, which can be applied both to the Klipse plugin's own elements, and to the CodeMirror editor's elements. Much of the styling you'll apply will be to CodeMirror, as it contains all the CSS classes to style the code itself. Surrounding CodeMirror is the Klipse plugin, the styles of which control the plugin's borders, and the executed code's output.

Changing the style of CodeMirror

You can change the theme of the CodeMirror editor simply by modifying its CSS. If you don't want to create your own theme, Farhad Gayour has an awesome list of ready-made themes you can select from. Have a look at the different themes by selecting them from the drop-down. Once you've found one you like, head to the theme repo to copy the CSS, paste it into a CSS file, and link to it from the HTML page containing your Klipse plugin.

Changing the style of the Klipse plugin

To change the style of the Klipse plugin's borders and the console output, you'll need to add a few extra style rules to your CSS file. These are:

  • .CodeMirror - modify the plugin's borders and CodeMirror's containing div
  • .CodeMirror:last-child::before - modify the console's title (i.e. the bit that says Output:)
  • .CodeMirror:last-child - modify the console area (i.e. the area beneath Output:)

You can see an example of styling Klipse in demos/styling. And here is a live demo

Klipse Community

Here are a couple of examples of blogs using the klipse plugin:

Ask us any question about the klipse plugin (integration, feature requests...) on Join the chat at

Use older versions

Since version 6.8.0, Klipse is published on npm. Therefore you can access the klipse files of a specific version from unpkg - a cdn for stuff that is published to npm.

For instance, The urls are for the version 6.8.0 are:

Host Klipse locally

You can download klipse with npm or bower.

In order to serve Klipse from your own server, you have to:

  1. Include in your page all the assets that you need from the dist folder: codemirror.css, klipse_plugin.js or klipse_plugin.min.js, (CodeMirror javascript addon), pretty_format.js (javascript beautifier)
  2. set klipse_settings.no_dynamic_scripts=true;

If you need more assets that are usually dynamically loaded by klipse, please download them manually.

Klipse App - Clojure Web Repl

Here is the information about the Klipse app

The Web REPL is live at

Here is the manual for the KLIPSE web repl.

Languages supported in the REPL: clojure and clojurescript.


See the LICENSE file for license rights and limitations (GNU General Public License v3.0).