Here is every Web Performance Test Tool I know of to help identify issues in your site/get you some key speed metrics. The idea is you think of a feature you want, e.g. "TTFB" or "locations" or "waterfall" and just Cmd + F on this page to find a tool that helps you with that thing.

Please let me know if you have other tools that belong here.

Simple Tools

Tools with simplicity as the appeal - great first checks.

• TestMySite from Netlify - Netlify's tool which checks TTFB and HTTPS and gives a score out of 100
• TestMySite from Google - mobile speed report from Google - lets you generate a report with recommendations for your team
• Bytecheck.com - gives you a simple waterfall breaking down Redirects + DNS + Connect + SSL + Send + Wait + Receive
• YellowLab.tools nice letter grades per section
• Pingdom Tools - you pick a location, it gives you some load time/page size stats, improvement opportunities, and a waterfall with a nice filter
• 24x7 Page Analyzer - you pick a location, it shows you a waterfall of requests with a PageSpeed score
• KeyCDN Speed Tool - gives you per-asset download breakdowns - a little TOO detailed to be useful
• Butterfly - I havent looked into this too much - Unlimited Automated Page Speed Monitoring & Tracking, Security Tracking & Performance Timing - founder is Ciprian on Twitter
• Lightest.app - Visualize web performance against competitors. Fast, simple, effective. strong recommend

Comprehensive Tools

Tools that try to give you the whole kitchen sink including waterfalls

• PageSpeed Insights - The original PageSpeed test from Google, aka Lighthouse run on the web - gives you FCP, FID, TTI, screenshots, opportunities, and Diagnostics. You can run this programmatically for free with Chrome's Crux API
• WebPageTest - This seems the most highly regarded in the webperf circles I know about. You pick a location and a browser. Gives you 3 runs, shows waterfall, and a bunch of stats with letter grades for compression/TTFB, FCP, Document Complete and Fully Loaded times.
• GTMetrix - Also super highly regarded. Gives you PageSpeed and YSlow recommendations, waterfall, historical graphs, and (for logged in users) filmstrips

Open Source, Self Hosted

• Perfume.js
• Falco - Open Source, self-hosted WebPageTest runner. automatically run audits & see the evolution of key performance metrics to easily spot regressions & audit the performance of individual URLs or entire user journeys
• Sitespeed - also Open Source, self hosted with monitoring :)

Services with Paid offerings

• PerfBeacon - runs Google Lighthouse/Pagespeed insights at a scheduled interval + when triggered by API calls. Price plans from 2.5k - 50k tests per month, 14 day free trial
• PageSpeedPlus - Google PageSpeed Insights Monitoring, Lighthouse Data - Lab & Field, Web Vitals, URL History, Email & Slack Alerts, Competitor Comparison, Full Site Scans
• Calibre - set performance budgets from various worldwide locations, receive regular reports, and get performance changes in Pull Requests. Price plans from 5k - 50k tests per month, 15 day free trial
• Amazon Cloudwatch Synthetics
• Simpleops.io
• Debugbear Track site speed and website quality for your production site and in CI. Catch regressions and benchmark against your competitors.
• Dareboost - looks simple, but actually does have filmstrip and waterfall and recommendations!! used to be free but now has a email signup wall
• RequestMetrics - Get simplified performance metrics and actionable alerts to make your website go fast - for $10/month. They blog on devto.

More uptime monitoring: https://www.supermonitoring.com/blog/website-monitoring-tools-market-in-2020/

Improvement Recommendations

These offer improvements but didn't quite make my cut for "Comprehensive Tools" - but are still noteworthy, esp Geekflare's security tools.

• Geekflare - Geekflare's set of 25 tools giving you everything from a Website Performance Audit to TTFB and Traceroute tests and other security related tests. The Audit gives a nice score and a lot of improvement recommendations.
• Pingdom Tools - you pick a location, it gives you some load time/page size stats, improvement opportunities, and a waterfall with a nice filter
• RequestMap from Webperf.Tools - Simon Hearnes' request map generator which focuses on visualizing Third Party Assets. Pick a location, and a device.
• ReportURI Security Headers - quick and easy way to check if sites have security headers like CSP and HSTS enabled
• Mozilla Observatory - teaching developers, system administrators, and security professionals how to configure their sites safely and securely.

Test Banks

Tools which ping your site from multiple locations to give you a global view.

• Sucuri Performance - pings your site from 16 locations worldwide and gives you connection and TTFB times.
• Website Speed Test from Dotcom Tools - ping 20+ locations and pick a browser, it shows you load times for first visit and repeat visit!
• KeyCDN Perf Tools - pings your site from 14 locations worldwide and gives you DNS/Connect times
• Latency.apex.sh - pings two URLs to compare latency from 13 locations. Good for comparing sites with and without a CDN.
• 🌟 Lighthouse Metrics - ping Lighthouse from multiple locations. Made by Chris.
• FastOrSlow - FastOrSlow does actual browser simulations from around 12 locations around the world. When we first architected it, we wanted to provide as many locations as possible including places like South Africa. That meant in some cases we needed actual bare-metal servers. So we built it on bare metal in data centers around the world. (Source)