Most web performance issues don't show up at one user... they show up at hundreds or thousands of users. Loadster is a cloud platform for simulating that kind of traffic and then seeing how your web application responds to it.
Loadster has Browser Bots and Playwright for real browser testing, or Protocol Bots for lightweight HTTP protocol testing. Load test scenarios mix bot types, ramp populations up over time, and run load tests with hundreds or thousands of concurrent bots from cloud regions of your choice.
The built-in reporting covers response time distributions, error rates, page-rendering metrics, and detailed traces about individual user journeys.
Loadster also has built-in 24/7 site and API monitoring. Loadster monitoring reuses the exact same scripts as synthetic checks running 24/7 from selected regions, with alerting through Slack, PagerDuty, SMS, or voice robocall whenever something goes wrong. Maintenance windows mute monitors during planned work so on-call pagers don't fire for non-events.
The free tier is 50 units of Loadster Fuel with no credit card required (enough to run a few load tests or maybe several weeks/months of monitoring). Usage scales from one-off load tests up to continuous testing and monitoring plans.