Question 1

Are dataset values unique across multiple bot groups?

Accepted Answer

When the same dataset is used by more than one bot group, each group gets its own copy, so unique-per-bot values are not unique across groups.

Question 2

Do Browser Bots support HTTP Basic or NTLM authentication?

Accepted Answer

How to supply HTTP Basic or NTLM authentication credentials to Loadster Browser Bots when load testing a site that requires them.

Question 3

What happens to the state (cache, cookies, and variables) between different iterations of the same bot?

Accepted Answer

Loadster has a setting for what to do with cache, cookies, and variables between iterations of the same bot.

Question 4

How come my test burned more or less fuel than estimated?

Accepted Answer

Sometimes a load test burns more (or less) Loadster Fuel than anticipated. Here are some reasons why.

Question 5

Can I call a JavaScript function or extract a value from the page?

Accepted Answer

Loadster's Evaluate Blocks can run custom JavaScript inside the bot's browser. Here's how to evaluate a simple value or promise.

Question 6

My Browser Bot traffic is showing up in Google Analytics! How do I make it stop?

Accepted Answer

How to configure Loadster and Google Analytics so that your bot traffic doesn't show up in the analytics.

Question 7

How can I create and sign a JWT in my script?

Accepted Answer

Many back-end APIs expect a JSON Web Token (JWT) as a way of authenticating requests or passing claims between systems. Here's how to make one in Loadster.

Question 8

Can I generate a random string, number, or UUID/GUID in my script?

Accepted Answer

Loadster has easy ways to generate random strings, numbers, or UUID/GUID for your load test scripts.

Question 9

What’s the best way to calculate how many bots I need for a load test?

Accepted Answer

How many bots does your load test require? Here's a quick formula to calculate the number of bots required for a load test by working backwards.

Question 10

How many concurrent bots or virtual users can Loadster run?

Accepted Answer

Loadster customers have run 170,000+ concurrent real Chrome browsers, and Protocol Bot capacity goes well into the millions. Here's how it scales.

Question 11

How can I ignore socket errors due to an untrusted TLS/SSL certificate?

Accepted Answer

How to configure Loadster to ignore self-signed or untrusted TLS/SSL certificates when load testing a site on a staging or development environment.

Question 12

Can I include a script in another script?

Accepted Answer

Code reuse is a good thing, and that includes test scripts. Here's how you can include one test script in another with Loadster.

Question 13

Can I make Loadster exclude error responses when calculating response times?

Accepted Answer

You might want to include or exclude errors from response time calculations. Here's how to do that in Loadster.

Question 14

What's the difference between latency and response time?

Accepted Answer

Latency is the network delay before data starts arriving; response time is the full wait for a complete response. Here's how the two differ in load testing.

Question 15

How do I make a test stop after X iterations?

Accepted Answer

In Loadster, bots normally repeat your script until time runs out. Here's how to set an iteration limit so bots stop after a specific number of runs.

Question 16

Loadster is reporting high response times, but I accessed the site myself and it seems fast. What's the difference?

Accepted Answer

If you're running a load test and Loadster reports high response times, but you access the site yourself and it's fast, there are a few things it might be.

Question 17

Loadster reports higher network throughput than my hosting provider shows. Why?

Accepted Answer

Why Loadster might report higher network throughput than your hosting provider. Common reasons for the discrepancy and how to interpret the numbers.

Question 18

How can I make my Browser Bot traffic show up in Google Analytics?

Accepted Answer

If your Browser Bot traffic isn't showing in Google Analytics, and you want it to, here's How to configure Loadster and Google Analytics.

Question 19

How do I manually set a cookie in a script?

Accepted Answer

Loadster handles most cookies automatically, but occasionally you might need to set one yourself. Here's how to set a cookie in your Loadster script.

Question 20

Can I use the Page Object Model (POM) with my Playwright scripts?

Accepted Answer

Loadster Playwright scripts are a single file, but you can still use the Page Object Model (POM) and other organization patterns. Here's how.

Question 21

How do I parse and validate a JSON response?

Accepted Answer

How to parse and validate JSON responses in a Loadster test script, to verify your API returns the expected data under heavy traffic.

Question 22

How do I parse and validate an XML response?

Accepted Answer

Validating an XML response in a load test is a way to validate the server response is what you expected. Here's how to do it in Loadster.

Question 23

How do I pass a Loadster variable into the browser so the page can read it?

Accepted Answer

How to expose dataset variables and bot context to JavaScript running inside the page with Browser Bots.

Question 24

How can I play a script that needs to reach a site on a private network?

Accepted Answer

Normally, Loadster scripts play from the public cloud. Run your own engines as script players if you need to hit a site on a private network.

Question 25

How do I manipulate range sliders, color pickers, and other specialized HTML inputs?

Accepted Answer

How to control range sliders, color pickers, and other HTML inputs with Loadster Browser Bots using JavaScript Evaluate Blocks.

Question 26

Does Loadster load test with real browsers or headless browsers?

Accepted Answer

Loadster's Browser Bots run real Chrome in headless mode: a full browser engine with real rendering and JavaScript, just without a visible window.

Question 27

What's the difference between requests per second, transactions per second, and concurrent users?

Accepted Answer

Requests per second, transactions per second, and concurrent users measure different things. Here's how they relate and how to convert between them.

Question 28

Is there a way to resize the browser window or switch to another window/tab?

Accepted Answer

Loadster's browser bots start with a single window with a viewport size of 1280x720 pixels, but you can change that.

Question 29

Is it possible to interact with inputs or other elements in an iframe?

Accepted Answer

Loadster's Browser Bots support special CSS-style selectors for interacting with an input or other element within an iframe.

Question 30

Does Loadster offer Single Sign-On (SSO)?

Accepted Answer

Loadster supports SAML2 for Single Sign-On (SSO). This is available with annual plans and custom plans upon request and we'd be happy to help you set it up.

Question 31

How do I make a bot stop playing the script if an error occurs?

Accepted Answer

Loadster has an option to immediately stop playing a script if validation fails or some other error happens. Otherwise, the script can keep playing.

Question 32

Can I set timers to measure key transactions in test script?

Accepted Answer

Loadster automatically measures most response times, but you can also add custom timers to measure specific transactions.

Question 33

Can I override DNS hostnames or use a custom hosts file?

Accepted Answer

How to override DNS hostnames in a Loadster load test, simulating a custom hosts file to point scripts at a staging or alternate environment.

Question 34

What happened to Speedway?

Accepted Answer

Speedway, our standalone site monitoring product, has been merged back into Loadster. Its monitoring capabilities now live in Site & API Monitoring.

Question 35

What is a good Apdex score?

Accepted Answer

An Apdex score above 0.85 is generally considered good. Here's how Apdex is calculated, what the thresholds mean, and how it relates to load test results.

Question 36

What is a load generator (load engine)?

Accepted Answer

A load generator is the machine that runs simulated users during a load test. In Loadster, load generation comes from cloud regions or self-hosted engines.

Question 37

What is a performance bottleneck?

Accepted Answer

A performance bottleneck is the one resource that limits your whole system's capacity under load. Here's how bottlenecks show up in load test results.

Question 38

What is think time (wait time) in load testing?

Accepted Answer

Think time, called wait time in Loadster, is the pause between a simulated user's actions. Realistic wait times are what make load test results trustworthy.

Question 39

What is throughput in load testing?

Accepted Answer

Throughput is the rate of work a system completes under load, measured in requests, pages, or bytes per second. Here's how to read it in load test results.

Question 40

What do p50, p80, p90, p95, and p99 response times mean in a load test?

Accepted Answer

Percentile response times like p50, p80, p90, p95, and p99 tell you what most users actually experience in a load test, unlike averages which hide outliers.

Question 41

When I play a script in the editor, where does the script traffic originate?

Accepted Answer

Normally, Loadster plays scripts from the public cloud. Here's how to control where the script traffic originates from when you run scripts in the editor.

Question 42

Can I get Loadster's IP addresses for my whitelist?

Accepted Answer

Is your firewall or load balancer blocking traffic based on IP address? Here's how to get Loadster's IP addresses so you can whitelist them.

Question 43

Why is Loadster saying the cloud capacity has been exceeded?

Accepted Answer

When you run a load test, Loadster launches instances in your choice of cloud regions, but there may be times when capacity is exceeded in a region.

Question 44

Can I write my Playwright scripts in TypeScript?

Accepted Answer

Loadster Playwright scripts support both JavaScript and TypeScript. You can paste in a .ts or .js Playwright test and it just works.

Frequently Asked Questions

Load Testing

General Scripting

Browser Bots

Protocol Bots

Playwright Bots

Miscellaneous