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JSON Derulo Build Status NPM version Dependency Status

Supported by Mashape Mashape logo

Derulo is a tool for building and manipulating JSON files.

Derulo Logo


Hand editing JSON kinda sucks. You have to go around quoting stuff and if you forget a comma or a colon everything breaks. Derulo offers a fast way of creating and editing JSON files.


Get Node.js then run

$ npm install -g derulo

Usage examples

For full usage instructions, see the help text.


Derulo video


derulo <filename> will open up a REPL where you can add multiple key-value pairs to be written to the file. To quit the REPL, and either save or discard the object you're build, press Ctrl+C at any time. Ctrl+D will quit the whole program with no prompt, so be careful!

The REPL is not fully finished yet, so use with caution.

Adding and editing

derulo package name Jason will add the pair "name": "Jason" to the file package.json in the current directory. If the file doesn't exist it will be created. If the key already exists, the value will be overwritten.

If the value is a number, boolean or null, it will be parsed as such. Everything else will be a string.


derulo -d package name will remove the name property from the file package.json. If no such key exists, nothing will happen.

Fuzzy matching

If you omit the extension from the filename, .json will be appended automatically (or .yml for YAML if the -y flag is passed). If this doesn't match either, a fuzzy search will be performed, finding the closest matching file. Therefore, pack, package and package.json are equivalent when running in this repository.


Derulo will attempt to auto-detect and preserve indentation on files. If this fails, it will fall back to 2-space indentation.

Planned features

  • Support for nested structures - arrays and objects.
  • Support for editing YAML too.


New features and bug reports/fixes are very welcome. Try and be consistent with existing style and all that.