WebPageTest is an incredibly useful resource for any web developer, but the information it provides becomes much more powerful when monitored regularly, rather than at isolated events. SpeedTracker runs on top of WebPageTest and makes periodic performance tests on your website and shows a visualisation of how the various performance metrics evolve over time.
This allows you to constantly evaluate how new features or infrastructural changes impact the perceived performance of your website.
Companies like Calibre or SpeedCurve offer this as a professional (and far more comprehensive) service, but not everyone can afford them. Whether you’re part of a small company or run a non-profit/open-source project, SpeedTracker can help you keep an eye on the performance of your website for free.
Tracking web performance for these organisations and many others: