Getting Started

Loadster is a load testing platform for testing your websites, web applications, and APIs. Load testing your site helps you prepare for high-traffic events by finding scalability problems ahead of time.

If you want to reduce the risk of your site crashing under heavy traffic, you’ve come to the right place.


If you’re new to load testing (or it’s been a while) you might want to brush up on a bit of general theory in our Introduction to Load Testing. There are also guides specific to Website Load Testing and API Performance Testing.

You might also review some best practices and pitfalls and glance over key concepts.

Ready to start testing with Loadster? Read on!

Bots & Scripting

Loadster runs bots to simulate real users interacting with your site. You control their behavior with scripts. Usually, you’ll want your scripts to mimic real user behavior on your site as closely as possible.

There are two types of bots, Protocol Bots and Browser Bots, and each type of bot runs its own type of script.

Protocol Scripts, executed by Protocol Bots, operate at the HTTP/HTTPS protocol layer. They’re ideal for low-level testing of APIs and simple static websites. A protocol script is essentially a sequence of HTTP requests, but you can use variables with validation and capturing to chain together dynamic requests and responses.

Browser Scripts, executed by Browser Bots, automate full headless web browsers. Real browser testing is the easiest and most realistic way to test modern websites and web applications. A browser script automates high-level actions like navigating to a URL, clicking on a button, or typing text into a field, so you don’t have to worry about the underlying protocol. The browser handles it.

Loadster’s built-in script editor makes it easy to record and modify both types of scripts. In the editor, you can play a script repeatedly with a single bot to make sure your script works as intended.

Load Testing

A load test is when you run many bots concurrently, so you can measure your site’s performance and stability under heavy load.

In Loadster, a load test scenario is a recipe for how to assemble the bots into a load test. A scenario configures how many groups of bots should run, which script each bot group should execute, and the ramp pattern each group should follow as the bots start and stop.

When you run a load test, your bots gather site performance metrics and errors as they test your site, and Loadster automatically assembles the data into graphs and tables. You can observe these metrics on a realtime dashboard while your load test runs.

After the test finishes, Loadster generates a report with high-level performance metrics and an assortment of graphs and tables, so you can further analyze the results of your load test.

Test Infrastructure

You can choose to run your bots from any of Loadster’s 29 cloud regions (recommended), or from your own self-hosted engines if you need to test on a private network.

After you’ve created test scripts and a repeatable load test scenario, consider adding load testing to your continuous integration pipeline so you can automatically test your site’s performance and scalability with each release or on a regular schedule.

Site Monitoring

Alongside load testing, you can also use your Loadster scripts for 24x7x365 Site & API Monitoring to make sure your site stays alive and functional. Unlike a load test that runs hundreds or thousands of bots concurrently, monitors run just one bot on a regular schedule and alert you of downtime or other problems with your site.

You can often reuse the same scripts for both load testing and monitoring. Loadster’s monitors test entire scripted flows through your site, so it’s more than just a simple uptime check.

Load testing and site monitoring are both a good idea if you want to reduce your risk of crashes and downtime.

FAQs and Guides

Alongside this manual, we’ve covered quite a few Frequently Asked Questions.

There are also several Guides, covering load testing and other performance engineering topics at a higher level than we do in this manual.

You can keep tabs on what’s new in Loadster each month in the Changelog.

Getting Help

We hope you’ll find everything you need in this manual, but load testing can be tricky, and there are edge cases we haven’t covered here.

If you don’t find what you need, email and we’ll help you out.