Your site has a breaking point. Load test to find it before your users do.

Create powerful test scripts with Playwright, Browser Bots, or Protocol Bots. Launch thousands of concurrent bots from 32 AWS and GCP cloud regions. Reuse the same scripts for load testing, stress testing, and synthetic monitoring.

1 What do you want to load test?
2 What type of bots?
3 How many concurrent bots? 5
4 Where will the bots run? North America (Any)
5 What kind of script?

Enter a URL to load test.

99.999%

Load testing + synthetic monitoring = high availability. Prepare for heavy traffic, react quickly to problems.

Loadster is a cloud-based performance engineering platform that uses the same scripts for load testing, stress testing, and synthetic monitoring, so you can proactively test and monitor your site's key pages and critical flows.

Load testing your site will determine ahead of time how it will handle heavy load in a real high-traffic event. Discovering your site's breaking point and then eliminating scalability bottlenecks will make your site more resilient and far less likely to crash when a surge of real traffic hits. Our guides walk through how to load test a website and how to stress test a web app.

Monitoring your site's critical flows around-the-clock is just as important. Even high-performance sites can suffer unplanned downtime. Active site monitoring, with bots constantly testing your site's most important user journeys, will help you detect problems and react to them before your users are impacted.

Loadster's combination of proactive load testing and reactive monitoring is just what you need for high-availability websites, web apps, and APIs.

Load Testing Pattern

Load Testing

Proactive

Load test your site with thousands of concurrent bots to prepare for heavy traffic. Find the breaking point, identify scalability bottlenecks, and optimize performance to prevent site crashes under peak load.

Find your site's breaking point before peak traffic catches you off guard.

More about load testing

Start Your Load Testing
Synthetic Monitoring Pattern

Synthetic Monitoring

Reactive

Monitor your site 24×7×365 with bots to detect problems quickly and ensure your site stays fast, functional, and always available. Bots test your site at all hours from multiple locations around the world.

Detect downtime and other problems before real users are impacted.

More about monitoring

Set Up Site Monitoring

Automate real headless Chrome browsers or lightweight HTTP clients. Your choice of Playwright, Browser Bots, or Protocol Bots.

Browser Bot

Browser Bots

Record scripts in your browser with Loadster's free extension and edit them visually. Add JavaScript if necessary. Browser Bots automate real headless Chrome browsers for realistic web application testing with a minimal learning curve.

Scripting style
Visual or JavaScript
Good for testing
Web Applications, Modern Websites
Fuel consumption
4× per bot-hour
Browser Bot Scripts
Protocol Bot

Protocol Bots

Protocol Bots execute scripted HTTP/S requests against your API or static website. Testing at the protocol layer is cost-effective and easily scales to hundreds of thousands of concurrent bots, and is ideal for testing HTTP APIs at scale.

Scripting style
Visual or JavaScript
Good for testing
APIs, Simple Websites
Fuel consumption
1× per bot-hour
Protocol Bot Scripts
Playwright Bot

Playwright

Run your Playwright Test scripts at scale through Loadster's cloud. Ideal for teams already using Playwright or who want programmatic control with an open source testing framework, combined with Loadster's cloud scaling and reporting.

Scripting style
JavaScript/TypeScript
Good for testing
Web Applications, Modern Websites
Fuel consumption
4× per bot-hour
Playwright Scripts
Start Testing for Free

Load testing with your favorite AI assistant. Control Loadster with Claude, ChatGPT, Codex, Cursor, VS Code, and other MCP clients.

Describe the flow you want to test in plain language. Your assistant writes the script, plays it with a single bot until every step passes, and builds a load test scenario that's ready to launch.

  • Scripts that actually work. Playwright, Browser Bot, or Protocol Bot scripts, played and fixed until they work.
  • Scenarios from a sentence. Bot counts, cloud regions, and ramp-up patterns, straight from your description.
  • Reports and incidents, explained. Your assistant reads the test report or a failed monitor cycle and helps work out what went wrong.
Connect Your AI Assistant
  1. You: write a loadster script for our checkout on staging.acmeoutfitters.com in a real browser. search for trail shoes, add one to the cart, check out as a guest. then set up a load test with 1000 bots from virginia and london
  2. get_documentation create_script "Guest Checkout" 7 steps from the homepage to the order confirmation
  3. play_script get_play_status Step 5 failed because “Continue as guest” never became clickable
  4. get_screenshot The screenshot shows a cookie banner covering the button
  5. update_script play_script get_play_status Dismissed the banner first, and all 7 steps passed in 9.2 seconds
  6. list_engines create_scenario "Guest checkout, 1,000 browsers" Saved to your Staging project

  7. Ready to go. Launching is your call, since a test this size runs unattended and uses Loadster Fuel. When it finishes, I'll read the report and help you analyze the results.

  8. Scenario
    Guest checkout, 1,000 browsers
    500 Browser Bots
    N. America - Virginia
    500 Browser Bots
    Europe - United Kingdom
    Ramp
    Up in 60s, hold 5 min
    Launch Test

Connect to the Loadster MCP server

Install the Loadster plugin, which adds the MCP server and a few load testing skills:

/plugin marketplace add loadster/loadster-mcp
/plugin install loadster@loadster

Then run /mcp, choose loadster, and approve the Loadster OAuth connection in your browser. To add just the server instead, run claude mcp add --transport http loadster https://api.loadster.com/mcp.

Claude Code setup guide »

Any other MCP client that supports remote servers over Streamable HTTP connects to the same URL, with OAuth or a personal access token. 

https://api.loadster.com/mcp

Setup guides for every client »

Load test on demand from 32 AWS and GCP cloud regions. Monitor continuously from 8 locations across 5 continents.

Loadster Global Network 32 regions online
AWS GCP Monitoring
Start Testing for Free

Performance engineering results with less time and effort. Loadster makes your team faster with browser-based scripting, fully managed infrastructure, live metrics, and automatic reporting.

  • Script Recording

    Record scripts right in your browser with the free Chrome or Firefox extension. Or add steps manually, if you prefer.

  • Quick Editing

    Edit your scripts and replay them with a single bot until it works perfectly. Choose between the graphical and text editor.

  • Instant Playback

    As you play scripts from your web browser, watch the results in real time as each step runs. Edit and repeat as necessary!

  • Diagnostic Traces

    After your script runs, you can inspect requests, responses, screenshots, and errors from every step.

  • Managed Cloud

    No need install anything or set up test infrastructure! Loadster spins up fully managed cloud instances in about 2-3 minutes.

  • Live Results

    As each load test runs, keep an eye on the real-time graphs and tables. Observe your site's response times, throughput, and errors.

  • Automatic Reports

    Loadster automatically generates a full test report with charts and tables after each test. No more tedious manual reporting.

  • Team Collaboration

    Invite your colleagues, and anyone on your team can create scripts, run tests, and share results. Make scalability a team effort!

  • AI Assistants & MCP

    Connect Claude, ChatGPT, or Cursor to Loadster. Your assistant writes and plays scripts, wires datasets, and builds scenarios.

Loadster scales with your testing and your budget. Choose between flexible pay-as-you-go and predictable subscription pricing.

Pay As You Go

Starting at $97 for 1,000 units

Purchase as much Loadster Fuel as you need for your load testing and monitoring. No commitment, just buy fuel when you need it.

Check Fuel Pricing

Loadster Team

$499 a month, billed annually

Load testing and monitoring for the whole team at a flat, predictable price. All-inclusive testing within your plan limits.

Check Team Pricing

Frequently Asked Questions

Can Loadster load test with real browsers?
Yes. Browser Bots drive real headless Chrome browsers, so a test runs the same pages and flows a person would. Record a script with the free browser extension and edit it in the web-based editor, adding JavaScript when you need it. Loadster customers have run load tests with more than 170,000 concurrent Chrome browsers, and well into the millions of Protocol Bots.
Can I run my existing Playwright scripts at scale?
Yes. Loadster runs standard Playwright Test scripts in JavaScript or TypeScript, usually with little or no modification. Each bot drives its own headless Chrome browser, and the same script can run as a load test from 32 AWS and GCP cloud regions or as a monitor.
Can Loadster load test HTTP APIs?
Yes. Protocol Bots are lightweight HTTP clients for APIs and simpler sites. You build the requests in the web-based editor or in JavaScript, and one test can mix Protocol Bots with Browser Bots and Playwright scripts.
Can I run a Loadster load test from more than one region?
Yes. Load tests run from 32 AWS and GCP cloud regions, and you don’t provision the infrastructure. For an app on a private network, a self-hosted Loadster engine runs inside your network while you control the test from the dashboard.
Can Loadster import JMeter, k6, or Locust scripts?
Yes. The importer accepts JMeter test plans (.jmx), k6 scripts (.js), and Locust files (.py), and it reports anything it couldn’t translate. Loadster has no LoadRunner (VuGen) importer.
Can I reuse a load test script as a monitor?
Yes. The same Playwright, Browser Bot, or Protocol Bot script can run as a 24/7 synthetic monitor. A monitor runs on a schedule from 8 locations and opens an incident when a step fails or exceeds your response time threshold.
Can my AI assistant write Loadster scripts?
Yes. The Loadster MCP server gives your AI assistant the ability to create Playwright, Browser Bot, and Protocol Bot scripts, as well as build load test scenarios, set up monitors, and analyze test results. Claude, ChatGPT, Cursor, and other MCP clients can connect to your account. You still launch the tests, enable the monitors, and spend the fuel.
Why use Loadster if AI can write my k6 or JMeter script?
First of all, AI can also write Loadster scripts and is very good at it! The Loadster MCP server gives your AI assistant the ability to create Playwright, Browser Bot, and Protocol Bot scripts, as well as build load test scenarios, set up monitors, and analyze test results. Writing a k6 or JMeter script was rarely the hard part, and AI makes that even quicker. What’s left is generating load from more than one machine and region, running real browsers at scale, and reading the results. When a site change breaks a script, that assistant can help fix it over the Loadster MCP server, and a monitor running the same script can tell you it broke. You still launch the test, enable the monitor, and spend the fuel. Loadster runs the test from 32 AWS and GCP cloud regions, with real Chrome browsers on managed infrastructure, real-time dashboards, and shareable reports.
Is a free open source tool like k6, JMeter, or Locust good enough?
Often, yes. For a small HTTP-level test from your own machine, a free open source tool is a fine first step, and an AI assistant can write the script quickly. It gets harder at scale: you provide and operate the load generators, real browsers need serious hardware, and reporting is up to you. If you outgrow running them yourself, Loadster can import JMeter, k6, and Locust scripts.
Can I try Loadster without a credit card?
Yes. Every new account starts with 50 units of free fuel, and no credit card is required. After that, pay-as-you-go Loadster Fuel means you pay for the fuel bots burn while they run. Editing scripts, designing scenarios, and reading reports don’t cost fuel.

Playwright load testing Synthetic monitoring Pricing Why use Loadster if AI can write your script How load testing with AI works

Loadster has optimized the performance, scalability, and uptime of thousands of sites. We're proud to be a testing platform of choice to elite teams.

  • Nginx
  • Wells Fargo
  • Amazon
  • Queensland Government
  • Accenture
  • Yale University
  • HBO
  • Mint Mobile
  • KPMG
  • Perficient
  • Dell
  • Pearson

Move fast
Don’t crash

Ready to cut your risk of downtime? Load test to prevent crashes. Monitor to react quickly.

Start Testing Your Site