HAR is the file suffix for files generated using the HTTP Archive format. It's a file specification for capturing the HTTP experience of downloading a web page: HTTP headers, file sizes, download times, etc. HAR is fairly new, but it's already supported by Firebug and HttpWatch.
PageSpeed (download) is a web performance analysis Firefox add-on
(similar to YSlow).
Recently, the PageSpeed team ported their logic to C++ and released it as the
This includes some commandline tools.
har_to_pagespeed for this utility.
HarViewer is an open source project from Honza for drawing an HTTP waterfall chart from HAR files.
Why is this useful?
Releasing the PageSpeed SDK (all open source) is one step closer to having a common performance metric across all web development tools and environments. Imagine being able to get the same performance analysis results from Firebug, Web Inspector, HttpWatch, Fiddler, Keynote, and Gomez. This will help us develop a common vocabulary and bring more consistency and quality to the field of web performance optimization.