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Asset packaging library. Concatenates, Minifies, and Compresses CSS and JavaScript

Project description

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What the heck is this?

Crammit is a small tool that provides both CSS and JavaScript concatenation, compression and some other asset management related goodies. If you’ve heard of Jammit for Rails then you can think of it as my attempt to provide a similar simple version in Python.


$ [sudo] pip install crammit

If you’re adventurous you can install a bleeding edge version from the git master branch:

$ [sudo] pip install git+

To install in development mode

$ git clone
$ python develop

Put it through its paces

$ crammit -c assets.yaml

See below about configuration file format and parameters


Use YAML file to configure Crammit. Here is a sample configuration file.

output: assets       # directory path relative to the current directory
fingerprint: true    # add sha1 hash to the output file name

js_minifier: ...     # optionally use a minifier other than slimit.
                     # expects a shell command that uses stdin/stdout.
js_minifier_options: # options dictionary to configure JS minifier
  mangle: True
  mangle_toplevel: True

  # 'common' is a bundle name, output file will have prefix 'common'
    - static/js/application.js
    - static/js/vendor/*.js
    # paths are relative to the current directory
    - static/js/utils.js

    # you can use Unix shell-style wildcards in file names
    - static/css/*.css
  • output - specifies relative path of an output directory where allgenerated files will be put.
  • fingerprint - either true or false. If true then SHA1 hash will be added to output bundle file names. The hash is calculated on concatenated original files before minification and gzip compressionis applied.

Every bundle will output 3 files. Let’s check out the output of the javascript common bundle.

  • common-{sha1}.js - concatenated original files
  • common-{sha1}.min.js - concatenated and minified files
  • common-{sha1}.min.js.gz - concatenated, minified, and gzipped files

Information file

Crammit produces a bundle information file in {output}/assetsinfo.yaml that contains different details about all generated bundles. The information includes SHA1 fingerprint (if enabled) for a bundle, output file names and their corresponding sizes in bytes.

  • raw - concatenated
  • min - concatenated and minified
  • gz - concatenated, minified, and gzipped
    - static/css/test1.css
    - static/css/test2.css
    fingerprint: 71fe4cba05a1a51023c6af4c4abf9c47ab21e357
      gz: base-71fe4cba05a1a51023c6af4c4abf9c47ab21e357.min.css.gz
      min: base-71fe4cba05a1a51023c6af4c4abf9c47ab21e357.min.css
      raw: base-71fe4cba05a1a51023c6af4c4abf9c47ab21e357.css
      gz: 108
      min: 235
      raw: 277
    - static/js/application.js
    - static/js/vendor/vendor1.js
    - static/js/vendor/vendor2.js
    fingerprint: 6493b619c73c49ce1f4dfe2c31d41902e98acaee
      gz: common-6493b619c73c49ce1f4dfe2c31d41902e98acaee.min.js.gz
      min: common-6493b619c73c49ce1f4dfe2c31d41902e98acaee.min.js
      raw: common-6493b619c73c49ce1f4dfe2c31d41902e98acaee.js
      gz: 56
      min: 41
      raw: 50
    - static/js/utils.js
    fingerprint: c3ef63280b954d99e8b13fc11ea3031caee77f1a
      gz: utils-c3ef63280b954d99e8b13fc11ea3031caee77f1a.min.js.gz
      min: utils-c3ef63280b954d99e8b13fc11ea3031caee77f1a.min.js
      raw: utils-c3ef63280b954d99e8b13fc11ea3031caee77f1a.js
      gz: 42
      min: 22
      raw: 24


  • CSS minification - cssmin
  • Stole nice idea of bundle information file - Squeezeit
  • JavaScript minifier - SlimIt


The MIT License (MIT)

Change History

0.5 (2012-06-24)

  • Run custom JS minifier with js_minifier option
  • Don’t minify files that contain ‘.min’ in their file name
  • Add semicolon between merged JS files for safety

0.4 (2012-03-17)

  • Added js_minifier_options configuration directive that specifies named parameters that are passed to the underlying JS minifier to configure it

0.3 (2012-03-12)

  • files option in assetsinfo.yaml that lists files processed to create a bundle
  • Python 2.6 support

0.2 (2012-02-12)

  • Public release

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