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BiSON.js - Binary Encoding for JavaScript

BiSON is size optimized binary encoding for JavaScript objects, it was designed for real time web games and other applications that might be bandwidth limited.

Output Size

BiSON saves between 20 to 45 percent of size when compared to JSON. With the average saving being around one third. In order to achieve a maximum of compression BiSON makes some trade offs, therefore it is not 100% compatible with JSON.

Valid BiSON

  • true, false, null
  • Any Number between -2147483647.99 and 2147483647.99 (inclusive)

Note: Floats are rounded to 2 decimal places

  • Object and Arrays of any size and nesting depth
  • Strings of any length

Just like with JSON, all data needs to be encapsulated in a top level Array or Object.

Important: For reasons of speed, BiSON does not perform any validation on the data you pass it. Therefore passing for example Numbers that are not in range will result in malformed output.


Depending on the input, BiSON under V8 is between 2 to 5 times faster than native JSON and just as fast as JSON in Firefox 4 Beta.

For more detailed results visit the JSPerf Benchmark.