node package manager


benchmark each release of a node module published on npm against each other release using a small command line tool


A command line tool to examine your code's performance over various releases.

  • Downloads all releases
  • runs the specified js file against all versions
  • shows you a graph of your module's performance (Note: this may or may not work depending on how your javascript file prints its results to stdout).
  • specialized to read ops/sec from stdout
  • releases with incompatible APIs will likely throw errors when the js file is run, and will be omitted aka set to 0. If the error is more serious, things may just crash and I'm sorry.

Example usage for testing the redis package, and running the file multi_bench.js against each release:

npmbench redis multi_bench.js
*****      ( XX ops/sec ) v0.0.1
*******    ( XX ops/sec ) v0.0.2
********   ( XX ops/sec ) v0.0.3
****       ( XX ops/sec ) v0.0.4
********** ( XX ops/sec ) v0.0.5
  • Output from each run of your js file will be put into a file named npmbench-moduleName@x.y.z.txt.
  • These are then parsed into json files which are put at npmbench-moduleName@x.y.z.json
  • makes it easy to run your own analysis of the numbers after all the benches have been run, or just grep through it :)

Why is this nice? Makes it easy to write your own parser for the output.


  • skip running a given bench if there is already a .txt file there for it
  • graph the graph with something fancier than asterisks on the command line.
  • split out the parsing stage so people can supply their own output parser (too much work?)
  • actually write the thing that aggregates all the json blobs into one graphable json blob