Loadster Manual

Loadster is a load testing platform for scalable websites, web applications, and APIs. If you want to reduce the risk of site failure due to high traffic, you’ve come to the right place.


New to load testing or it’s been a while? You might like an introduction to load testing. You can also review best practices and pitfalls and learn about key concepts in Loadster.

How Scripting Works

Loadster runs bots to simulate real users interacting with your site, and you control their behavior with scripts.

Protocol Scripts fire off a sequence of HTTP requests, and they’re ideal for testing APIs and simple static sites. A protocol script is essentially a sequence of HTTP requests with automatic response validation and capturing.

Browser Scripts run real headless web browsers, and they’re the easiest and most realistic way to test complex websites and dynamic web applications. A browser script performs high-level browser operations like navigating to a URL, clicking on a button, typing text into a field, and so on.

Take a look at code blocks to take scripting to another level with looping and conditional logic. Also, check out variables and datasets for ways to inject dynamic data so each bot interacts with your site a little differently.

The Load Testing Process

A script controls the behavior of a single bot, but it takes many bots running together to make a load test.

Create a scenario to define groups of bots and tell how each group should behave: what script they should run, what cloud region or engine they’ll run from, and so on. Once you’ve created a scenario to define bots and groups, you’re ready to launch a load test.

As the test runs, Loadster gathers realtime results. After the test finishes you’ll have a test report so you can analyze the test results.

Load Test Infrastructure

Loadster runs bots from your choice of Loadster cloud regions or from your own self-hosted Loadster Engines.

Once you’ve got a working and repeatable load test, you can (optionally) run it on a regular schedule from your continuous integration tool.


Loadster integrates with our companion application, Speedway, for 24x7 site and API monitoring.

We also have integrations with other tools including Slack and Pagerduty, or you can implement your own integration with webhooks.

FAQs and Testing Guides

Alongside this manual, we’ve covered some Frequently Asked Questions and occasionally publish Articles & Guides about load testing and other performance engineering topics.

You can also keep tabs on what’s new with Loadster with the Changelog.

Getting Help

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

If you don’t find what you need, shoot an email to help@loadster.app and we’ll help you out.