YSlow
Official YSlow Open Source Project Website. YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages.
15 Alternatives To YSlow
AppDynamics
Get real-time insight from your apps using Application Performance Management—how they’re being used, how they’re performing, where they need help.
Fiddler
Fiddler is a debugging program for websites.
GTmetrix
GTmetrix is a free tool that analyzes your page’s speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers actionable recommendations on how to fix them.
Google Lighthouse
Lighthouse is an open-source, automated tool for improving the quality of web pages.
HttpWatch
HttpWatch: The ultimate HTTP Sniffer for Chrome, IE and iOS
Loader
Load testing and tracking application
Postman Collections
Biggest library of ready-made API collections for Postman
Ryte
Ryte is a web-based software invented for technical optimization for search engines and improvement of websites.
SEO PowerSuite
Get all SEO tools in one pack - download free edition of SEO PowerSuite and get top 10 rankings for your site on Google and other search engines!
UbikLoadPack
UbikLoadPack provides plugins for Apache JMeter to load test Video Streaming, GWT Applications, Java Serialization based products and Flex.
WebPagetest
Run a free website speed test from multiple locations around the globe using real browsers…
Website Speed Test by Pingdom
Pingdom is a website performance monitoring software.
XRebel
XRebel is a lightweight Java profiler that helps developers find and fix common problems in their application as they code.