# Loadster

> Loadster is a cloud-based load testing and stress testing platform for websites, web applications, and APIs. It simulates virtual users, called bots, to measure performance and scalability under heavy traffic and to find where a system breaks. A key differentiator is real browser load testing at massive scale: Browser Bots and Playwright Test scripts drive real Chrome browsers, and Loadster customers have run load tests with more than 170,000 concurrent browsers. Lightweight Protocol Bots run HTTP-level tests that scale to millions of concurrent bots. Another differentiator is that the same load testing scripts can also power 24/7 synthetic monitoring, so a script written for a load test can watch the site around the clock and alert on downtime or broken user flows.

## Key Capabilities

- **Load Testing**: Run thousands of concurrent virtual users against your site to find performance bottlenecks before real users do.
- **Real Browser Scale**: Browser Bots and Playwright Test scripts drive real Chrome browsers on managed cloud infrastructure, with no fixed platform cap; practical scale depends on regions and cloud capacity. How it scales, and what limits it, is documented at https://loadster.com/faqs/maximum-concurrent-bots-or-virtual-users/index.md
- **Site & API Monitoring**: Continuously monitor websites, web applications, and APIs around the clock for downtime and broken user flows, using the same scripts that drive load tests.
- **Three Scripting Options**: Protocol Bots (HTTP-level), Browser Bots (real Chrome browsers), and Playwright Test scripts (code-first JavaScript). Browser and Playwright scripts are written as user actions, navigating, clicking and typing, rather than as chains of individual HTTP requests that have to be strung together by hand. For modern websites and web applications that is usually both quicker to script and more realistic, because each bot exercises the same client-side code path as a real user. Protocol Bots cost far less per bot and remain the better fit for APIs and simple sites, so many teams mix the two: real browsers for critical flows, protocol for broad throughput. That trade-off is covered at https://loadster.com/guides/load-testing/index.md
- **32 Cloud Regions**: Run tests from AWS and GCP regions worldwide, or self-host engines on your own infrastructure.
- **CI/CD Integration**: Automate load testing in your continuous integration pipeline.

## Pricing
Loadster is powered by Fuel, a unified currency for load testing and monitoring. Bots burn fuel when they run. Every account starts with 50 free units. Monthly Fuel Plans (1K–20K units, $77–$797/month) offer a discount and unused fuel rolls over. Pay-as-you-go fuel ($97–$997 per 1K–20K units) never expires. Monitoring Plans start at $29/month. Protocol Bots burn 1x fuel; Browser Bots and Playwright scripts burn 4x. Custom, annual, and bring-your-own-cloud plans are also available.

Full plan details: https://loadster.com/pricing/

## How Loadster Compares

- **Versus open source tools** (JMeter, k6, Gatling, Locust): those are free and code-first, and run on infrastructure you provide and operate. Loadster is a managed platform with 32 cloud regions, a visual script editor alongside code, and real browser testing at a scale that is impractical to self-host.
- **Versus hosted JMeter services** (BlazeMeter): Loadster is a native platform rather than a JMeter runner. Scripts are authored in Loadster's own editor or as Playwright tests, not as JMX.
- **Versus enterprise suites** (LoadRunner): Loadster is self-service and usage-priced, with no seat licensing and no professional services engagement required to run a test.
- **The main differentiator is real browser scale**: Loadster customers have run tests with more than 170,000 concurrent real Chrome browsers. Tools that offer a browser mode generally cap it far lower — Grafana Cloud k6, for instance, limits browser virtual users to 1,000 per test.
- **Not the right tool for**: profiling code inside your application, APM and observability (Loadster generates load and monitors from outside; it does not instrument your app), load testing entirely from a developer's own machine, or testers with no budget for tools.

Head-to-head comparisons, with sources, are under Tool Comparisons below.

## Links

- [Loadster Website](https://loadster.com/)
- [Pricing](https://loadster.com/pricing/)
- [Support](https://loadster.com/support/)
- [Contact](mailto:help@loadster.com)

## Developer Resources

- [AI Load Testing](https://loadster.com/ai-load-testing/): Overview of load testing with AI assistants — connect Claude, ChatGPT, or Cursor to Loadster over MCP and let them write scripts, build scenarios, and analyze results, while you launch the tests.
- [Loadster MCP Server](https://loadster.com/manual/mcp/index.md): Built-in Model Context Protocol (MCP) server at https://api.loadster.com/mcp, so AI assistants like Claude can write and play scripts, build load test scenarios, set up monitors, and analyze test results. Connects with OAuth, or with a personal access token from the dashboard for headless clients.
- [Loadster MCP on GitHub](https://github.com/loadster/loadster-mcp): Setup snippets for each MCP client, the Claude Code plugin (`/plugin marketplace add loadster/loadster-mcp`, then `/plugin install loadster@loadster`), and the official MCP Registry metadata for `com.loadster/loadster-mcp`.
- [Loadster REST API](https://loadster.com/manual/rest-api/index.md): The REST API at https://api.loadster.com for projects, scripts, scenarios, datasets, monitors, and load test results, authenticated with a personal access token from the dashboard, plus the trigger endpoints CI pipelines call without a token to launch load tests. OpenAPI spec: https://api.loadster.com/openapi.json
- [Loadster CLI](https://github.com/loadster/loadster-cli): Open source command line tool for playing local scripts and launching load tests, available as native binaries for Windows, Mac, and Linux. Usage docs: https://loadster.com/manual/loadster-cli/index.md
- [Load Testing with Continuous Integration](https://loadster.com/manual/load-testing-with-continuous-integration/index.md): Automate load tests from Jenkins, GitHub Actions, or any CI/CD pipeline.
- [OpenAPI/Swagger Import](https://loadster.com/manual/protocol-scripts/openapi-swagger/index.md): Generate load test scripts from an OpenAPI or Swagger specification.
- [Code Blocks](https://loadster.com/manual/code-blocks/index.md): Script advanced load test behavior in JavaScript.

## Documentation

- [Loadster Manual](https://loadster.com/manual/index.md): The Loadster manual and documentation. Loadster is a cloud-hybrid load testing platform for building scalable websites, web applications, and APIs.
- [Connecting AI Assistants to Loadster (MCP)](https://loadster.com/manual/mcp/index.md): Connect Claude, ChatGPT, Cursor, Codex, and other AI assistants to the Loadster MCP server to write and play scripts, build load tests, and read results.
- [Loadster Cloud Regions in AWS and GCP](https://loadster.com/manual/cloud-regions/index.md): Loadster can launch clusters on demand for your load tests, from a wide range of geographic regions and across multiple cloud providers.
- [Loadster REST API: Automate Load Tests and Monitors](https://loadster.com/manual/rest-api/index.md): Call the Loadster REST API with a personal access token to manage scripts, scenarios, monitors, and load test results, or launch load tests from CI.
- [Protocol Scripts in Loadster](https://loadster.com/manual/protocol-scripts/index.md): Loadster's protocol scripts run automated HTTP/HTTPS requests for testing websites and APIs. Chain together requests, add validation, and capture variables.
- [Site & API Monitoring](https://loadster.com/manual/monitoring/index.md): Monitor your site 24/7/365 with Loadster scripts. Bots run on a schedule and alert you if your site goes down or breaks, so you can take action.
- [Browser Bot Scripting](https://loadster.com/manual/browser-scripts/index.md): Loadster's browser scripts control real headless Chrome browsers. They're the most realistic way to test complex web applications.
- [Incidents & Notifications](https://loadster.com/manual/incidents-and-notifications/index.md): Loadster monitors open and close incidents whenever problems are detected, and notify you according to your notification policies.
- [Integrating Loadster with Opsgenie](https://loadster.com/manual/integration-with-opsgenie/index.md): Are you using Opsgenie for incident alerting? Here's how to integrate Loadster with Opsgenie for speedy incident response and escalation.
- [Load Testing On-Premises with Loadster Engine](https://loadster.com/manual/testing-with-loadster-engine/index.md): If you need to load test on-premises or in a private cloud environment, you can run your own Loadster Engines and control them from Loadster.
- [Hosted Status Pages](https://loadster.com/manual/status-pages/index.md): When Loadster is monitoring your site, a status page displays current monitoring data and uptime to your team or the general public.
- [Integrating Loadster with PagerDuty](https://loadster.com/manual/integration-with-pagerduty/index.md): Integrate Loadster with PagerDuty to create incidents when a monitor fails, and automatically resolve them when it recovers.
- [Playwright Scripting](https://loadster.com/manual/playwright-scripts/index.md): Loadster supports the Playwright Test framework for load testing and monitoring, ideal for developers who prefer writing tests in JavaScript or TypeScript.
- [Terms & Definitions](https://loadster.com/manual/terms-and-definitions/index.md): Key terms and definitions related to load testing web applications, web services, and static websites with Loadster.
- [Using the Loadster CLI](https://loadster.com/manual/loadster-cli/index.md): The Loadster CLI lets you launch load tests and check results from the command line, enabling CI/CD integration with Jenkins, GitHub Actions, and more.
- [Code Blocks for Advanced Scripting](https://loadster.com/manual/code-blocks/index.md): JavaScript code blocks in Loadster. Use code blocks in Protocol Scripts and Browser Scripts for function reuse, looping, and conditional logic.
- [Integrating Loadster with Slack](https://loadster.com/manual/integration-with-slack/index.md): Here's how to integrate Loadster with Slack, so you can find out quickly when monitors fail and recover or your team runs tests.
- [Load Testing with Continuous Integration](https://loadster.com/manual/load-testing-with-continuous-integration/index.md): How to integrate Loadster load testing into your CI/CD pipeline, so you can automatically track performance changes with every build or release.
- [Integrating Loadster with VictorOps (Splunk On-Call)](https://loadster.com/manual/integration-with-victorops/index.md): How to integrate Loadster with VictorOps (now Splunk On-Call) for fast incident routing and resolution.
- [Script Variables & Expressions](https://loadster.com/manual/variables-and-expressions/index.md): Use variables and expressions in Loadster to add dynamic data to your test scripts. Prepopulate variables from a dataset or set them at runtime.
- [Dynamic Datasets and Script Variables](https://loadster.com/manual/dynamic-datasets/index.md): Loadster's dynamic datasets are a way to prepopulate your script variables with canned data, such as user accounts or search phrases. Here's how.
- [Integrating Loadster with Webhooks](https://loadster.com/manual/integration-with-webhooks/index.md): How to integrate Loadster with your own systems or a system of your choosing with flexible webhooks.
- [Load Test Scenarios and Configuration](https://loadster.com/manual/load-test-scenarios/index.md): How to configure a Loadster load test scenario: choose how many bots run your scripts, from which cloud regions, and with what ramp-up schedule.
- [Running Load Tests](https://loadster.com/manual/running-load-tests/index.md): Here's how to launch and run load tests with Loadster, observing results with the real-time dashboard and charts. What do all the graphs mean?
- [Analyzing & Interpreting Load Test Results](https://loadster.com/manual/analyzing-test-results/index.md): How to read and interpret Loadster load test reports, including response times, throughput, error rates, and resource utilization metrics.
- [Loadster Single Sign-On Guide](https://loadster.com/manual/sso/index.md): Loadster offers SSO with SAMLv2 with certain annual and custom plans. Setting up Single Sign-On is generally fairly straightforward.

### Protocol Scripts in Loadster

- [Validation Rules in Protocol Scripts](https://loadster.com/manual/protocol-scripts/validation-rules/index.md): Using validation rules in Loadster. Validating response time, response size, and content. Advanced JavaScript validators.
- [Capturing Rules for Protocol Scripts](https://loadster.com/manual/protocol-scripts/capturing-rules/index.md): Using capturing rules in a Loadster protocol script, to capture or extract values from an HTTP response, and use them later in your script.
- [OpenAPI/Swagger Import](https://loadster.com/manual/protocol-scripts/openapi-swagger/index.md): Loadster integrates with OpenAPI and Swagger, so you can easily create steps in your script from an API specification.

### Browser Bot Scripting

- [Evaluate Blocks for Browser Scripts](https://loadster.com/manual/browser-scripts/evaluate-blocks/index.md): When normal browser automation isn't cutting it, use Evaluate Blocks to run or evaluate custom JavaScript inside the browser with Loadster.

### Playwright Scripting

- [Playwright Bot Reference](https://loadster.com/manual/playwright-scripts/bot/index.md): The @loadster/bot module for Playwright scripts — access dataset variables, bot metadata, and timing functions in your Playwright tests.
- [Organizing Playwright Scripts (POM)](https://loadster.com/manual/playwright-scripts/organizing-scripts/index.md): How to organize Playwright scripts in Loadster—start simple, then add helper functions, page objects (POM), and fixtures as your scripts grow.

### Code Blocks for Advanced Scripting

- [Bot Object Reference](https://loadster.com/manual/code-blocks/bot/index.md): The bot object in Loadster code blocks - methods for timing control, variable management, iteration handling, bot identification, and test flow control.
- [HTTP Object Reference](https://loadster.com/manual/code-blocks/http/index.md): The http object in Loadster code blocks - methods for making HTTP requests, managing headers, and handling authentication programmatically.
- [Browser Object Reference](https://loadster.com/manual/code-blocks/browser/index.md): The browser object in Loadster code blocks - methods for page interaction, window management, authentication, and browser configuration control.
- [Formats Object Reference](https://loadster.com/manual/code-blocks/formats/index.md): The formats object in Loadster code blocks - methods for encoding, decoding, timestamp generation, UUIDs, and random data creation for testing.
- [XML Object Reference](https://loadster.com/manual/code-blocks/xml/index.md): The XML object in Loadster code blocks - methods for parsing XML data, navigating elements, and extracting values using the xmldoc library.
- [JSON Object Reference](https://loadster.com/manual/code-blocks/json/index.md): The JSON object in Loadster code blocks - methods for parsing JSON data, creating payloads, and validation using standard JavaScript JSON methods.
- [Crypto Object Reference](https://loadster.com/manual/code-blocks/crypto/index.md): The crypto object in Loadster code blocks - methods for hashing, HMAC generation, authentication signatures, and cryptographic functions.

## Guides

- [Software Performance Engineering: A Practical Guide](https://loadster.com/guides/performance-engineering/index.md): Software performance engineering builds speed and scalability into systems from design through production. Learn the practice, tools, and where testing fits.
- [Load Testing Guide: Types, Tools, and Best Practices](https://loadster.com/guides/load-testing/index.md): Load testing simulates heavy traffic to measure your site's performance and scalability. Learn the types of load tests, what tools are used, and how to run one.
- [How to Load Test a Website: A Step-by-Step Guide](https://loadster.com/guides/website-load-testing/index.md): How to load test a website, step by step: plan your traffic, build realistic test scripts, run the load test, and read the results with confidence.
- [Performance Testing Guide: Types, Metrics, and Process](https://loadster.com/guides/performance-testing/index.md): Performance testing measures how a system responds under realistic and heavy usage. Learn the types of performance tests, key metrics, and how to run them.
- [API Load Testing and Performance Testing Guide](https://loadster.com/guides/api-performance-testing/index.md): How to load test an API: tools, methods, metrics, and pitfalls. A practical guide to API performance testing for REST, GraphQL, and gRPC.
- [Load Testing vs Stress Testing vs DDoS: The Differences](https://loadster.com/guides/load-testing-stress-testing-and-ddos/index.md): Load testing, stress testing, and DDoS attacks all generate heavy traffic. Here's what each means and how to tell them apart.
- [Synthetic Monitoring: Tools and Techniques](https://loadster.com/guides/synthetic-monitoring/index.md): Synthetic monitoring tests your site or API from outside on a schedule, catching downtime and slowdowns before users do. Learn how it works and the tools.
- [Load Testing vs Stress Testing: Key Differences Explained](https://loadster.com/guides/load-testing-vs-stress-testing/index.md): Load testing and stress testing are often confused. Here's the real difference, when to use each, and how they fit in a performance engineering program.
- [Quick and Dirty Performance Tuning: A Pragmatic Approach](https://loadster.com/guides/quick-and-dirty-performance-tuning/index.md): A guide to quick performance tuning. Use a reproducible load test to measure the impact of each optimization change.
- [API Monitoring: Uptime, Response Time, and Correctness](https://loadster.com/guides/api-monitoring/index.md): API monitoring checks your endpoints on a schedule for uptime, response time, and correct responses. What to monitor, how to script it, and how to alert.
- [Synthetic Monitoring vs Real User Monitoring (RUM)](https://loadster.com/guides/synthetic-monitoring-vs-real-user-monitoring/index.md): Synthetic monitoring runs scripted checks on a schedule; real user monitoring (RUM) measures actual visitors. How they differ and why most teams use both.
- [Synthetic Transaction Monitoring: Watching User Journeys](https://loadster.com/guides/synthetic-transaction-monitoring/index.md): Synthetic transaction monitoring scripts multi-step user journeys like login and checkout, then runs them on a schedule to catch broken flows early.
- [Web Application Stress Testing: Practical Tips and Examples](https://loadster.com/guides/web-application-stress-testing/index.md): Stress testing a web application means pushing it past capacity. Stateful flows, databases, and client-side rendering create failure modes that need attention.
- [Load Testing Costs and Benefits: When Is It Worth It?](https://loadster.com/guides/weighing-the-costs-of-load-testing/index.md): A guide to the costs and benefits of load testing. When is it worth the investment, and when might you reasonably skip it?
- [Capacity Planning for Servers, Cloud, and Web Apps](https://loadster.com/guides/capacity-planning-for-web-apps/index.md): A practical guide to capacity planning for servers, cloud infrastructure, and web applications, so you can handle expected demand and traffic spikes.
- [How Many Concurrent Users Can Your Website Handle?](https://loadster.com/guides/how-many-concurrent-users/index.md): How many concurrent users your website can handle depends on your stack, not just server specs. Rough estimates, plus how to measure your real limit.
- [IT Capacity Management for Cloud and Web Applications](https://loadster.com/guides/capacity-management/index.md): Capacity management is the ongoing practice of matching IT capacity to demand. Learn the process, how it differs from planning, and where testing fits.
- [Concurrent Users: Definition and Formulas](https://loadster.com/guides/concurrent-users/index.md): Concurrent users are the visitors on your site at the same moment. Learn how they differ from visits and RPS, and how to calculate them from analytics.
- [Soak Testing: Finding Memory Leaks and Slow Burns](https://loadster.com/guides/endurance-testing/index.md): Soak testing (also called endurance testing) runs sustained load for hours or days to surface memory leaks and other issues that take time to appear.
- [Front-End vs. Back-End Performance: Where to Focus First](https://loadster.com/guides/front-end-vs-back-end-performance/index.md): Under peak traffic, the usual 80/20 front-end/back-end ratio can flip. Here's how to tell the difference and where to focus your optimization.
- [Concurrency Testing: Deadlocks & Race Conditions](https://loadster.com/guides/concurrency-testing/index.md): Concurrency testing checks that a system stays correct when many users act at the same instant, catching race conditions, deadlocks, and data corruption.
- [Capacity Testing: Finding Your True Maximum Load](https://loadster.com/guides/capacity-testing/index.md): Capacity testing finds the maximum load a system can handle while still meeting performance targets, so you know your headroom before traffic peaks.
- [Scalability Testing: Scale Up, Find Bottlenecks](https://loadster.com/guides/scalability-testing/index.md): Scalability testing measures how performance changes as load and resources grow, so you can verify that adding servers actually adds capacity.
- [Spike Testing: Preparing for Sudden Traffic Surges](https://loadster.com/guides/spike-testing/index.md): Spike testing simulates a sudden burst of traffic to see whether your site absorbs the surge and recovers gracefully. Here's how to plan and run one.
- [Load Testing Best Practices: Tips, Pitfalls, and Checklist](https://loadster.com/guides/load-testing-best-practices/index.md): A guide to load testing best practices, common pitfalls, and a checklist for accurate results. Covers user simulation, requirements, and test reporting.


## Tool Comparisons

- [Best Synthetic Monitoring Tools Compared (2026)](https://loadster.com/compare/synthetic-monitoring-tools/index.md): Compare the best synthetic monitoring tools for 2026: Datadog, Checkly, Loadster, Grafana Cloud, Dynatrace, Pingdom, and more. Features, pricing, and fit.
- [Best Load Testing Tools and Platforms (2026)](https://loadster.com/compare/load-testing-tools/index.md): Compare the best load testing tools for 2026 — Loadster, JMeter, k6, Gatling, BlazeMeter, LoadRunner. Open source vs cloud. Pricing, features, fit.
- [Best Pingdom Alternatives for Synthetic Monitoring (2026)](https://loadster.com/compare/pingdom-alternatives/index.md): The best Pingdom alternatives in 2026: Loadster, Checkly, Better Stack, Site24x7, Datadog, and Uptime Kuma, with Pingdom pricing changes explained.
- [Datadog Synthetic Monitoring: Pricing & Alternatives (2026)](https://loadster.com/compare/datadog-synthetic-monitoring-alternatives/index.md): How Datadog Synthetics pricing works in 2026, with worked cost examples, plus the best Datadog Synthetic Monitoring alternatives and how they're priced.
- [UptimeRobot Alternatives with Transaction Checks (2026)](https://loadster.com/compare/uptimerobot-alternatives/index.md): Outgrown UptimeRobot? The best UptimeRobot alternatives for browser and API transaction checks: Loadster, Checkly, Better Stack, Grafana Cloud, Pingdom.
- [Best JMeter Alternatives for Load Testing (2026)](https://loadster.com/compare/jmeter-alternatives/index.md): The best JMeter alternatives for load testing in 2026 — Loadster, k6, Gatling, Locust, and hosted JMeter — with fact-based reasons to switch or stay.
- [Best k6 Alternatives for Load Testing (2026)](https://loadster.com/compare/k6-alternatives/index.md): The best k6 alternatives in 2026 — Loadster, Grafana Cloud k6, Gatling, Locust, and Artillery — with fact-based reasons to switch tools or stay put.
- [Best LoadRunner Alternatives for Load Testing (2026)](https://loadster.com/compare/loadrunner-alternatives/index.md): The best LoadRunner alternatives in 2026 — Loadster, Tricentis NeoLoad, and BlazeMeter — with fact-based advice on migrating off enterprise licensing.
- [Gatling vs k6: Load Testing Tools Compared (2026)](https://loadster.com/compare/gatling-vs-k6/index.md): Gatling vs k6 compared: scripting languages, reports, efficiency, and paid cloud options, with fact-based advice on which load testing tool fits your team.
- [JMeter vs LoadRunner: Load Testing Compared (2026)](https://loadster.com/compare/jmeter-vs-loadrunner/index.md): JMeter vs LoadRunner compared: cost, scripting, protocol coverage, and enterprise fit, with fact-based advice for choosing between free and enterprise.
- [JMeter vs Locust: Load Testing Tools Compared (2026)](https://loadster.com/compare/jmeter-vs-locust/index.md): JMeter vs Locust compared: scripting, protocols, distributed scale, and learning curve, with fact-based advice on which load testing tool fits your team.
- [k6 vs JMeter: Load Testing Tools Compared (2026)](https://loadster.com/compare/k6-vs-jmeter/index.md): k6 vs JMeter compared: scripting, protocol coverage, scale, CI/CD, and learning curve, with fact-based advice on which load testing tool fits your team.
- [Locust vs k6: Load Testing Tools Compared (2026)](https://loadster.com/compare/locust-vs-k6/index.md): Locust vs k6 compared: Python vs JavaScript scripting, per-machine efficiency, distributed scale, and CI/CD, with fact-based advice on which tool fits.
- [Loadster vs BlazeMeter: Load Testing Tools Compared (2026)](https://loadster.com/compare/loadster-vs-blazemeter/index.md): Loadster vs BlazeMeter compared: native platform vs hosted JMeter, real browser load testing, pricing, and which cloud load testing tool fits your team.
- [Loadster vs JMeter: Load Testing Tools Compared (2026)](https://loadster.com/compare/loadster-vs-jmeter/index.md): Loadster vs Apache JMeter compared: scripting, real browser load testing, cloud scale, pricing — plus how to import your JMX test plans into Loadster.
- [Loadster vs LoadRunner: Load Testing Tools Compared (2026)](https://loadster.com/compare/loadster-vs-loadrunner/index.md): Loadster vs LoadRunner (OpenText Performance Engineering) compared: scripting, browser testing, licensing costs, and when a lighter platform fits.
- [Loadster vs Locust: Load Testing Tools Compared (2026)](https://loadster.com/compare/loadster-vs-locust/index.md): Loadster vs Locust compared: Python scripting, real browser load testing, distributed scale, pricing — plus how to import your locustfile into Loadster.
- [Loadster vs k6: Load Testing Tools Compared (2026)](https://loadster.com/compare/loadster-vs-k6/index.md): Loadster vs k6 compared: scripting, real browser load testing, cloud scale, pricing, and CI/CD — with fact-based advice on which tool fits your team.


## FAQs

- [Are dataset values unique across bot groups?](https://loadster.com/faqs/dataset-values-unique-across-bot-groups/index.md): 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.
- [Authenticating with HTTP Basic or NTLM authentication](https://loadster.com/faqs/set-http-basic-or-ntlm-authentication-for-browser-bots/index.md): How to supply HTTP Basic or NTLM authentication credentials to Loadster Browser Bots when load testing a site that requires them.
- [Can AI Run Load Tests and Set Up Monitors?](https://loadster.com/faqs/ai-assistant-run-load-tests/index.md): An AI assistant can write and play scripts, build load test scenarios, and set up monitors in Loadster, but launching a full load test stays your call.
- [Connecting an AI Assistant to the Loadster MCP Server](https://loadster.com/faqs/connect-to-loadster-mcp-server/index.md): Point your AI assistant at the Loadster MCP server at api.loadster.com/mcp and connect with OAuth or a token. Setup steps for Claude, ChatGPT, and more.
- [Cookies and variables between load test iterations](https://loadster.com/faqs/cookies-and-variables-between-iterations/index.md): Loadster has a setting for what to do with cache, cookies, and variables between iterations of the same bot.
- [Estimated and actual Loadster Fuel usage](https://loadster.com/faqs/estimated-and-actual-fuel-usage/index.md): Load tests sometimes burn more or less Loadster Fuel than the scenario estimate. Duration, unfinished iterations, and early stops are the usual reasons.
- [Evaluating a value or promise with Browser Bots](https://loadster.com/faqs/evaluating-a-value-or-promise-inside-the-browser/index.md): Loadster's Evaluate Blocks can run custom JavaScript inside the bot's browser. Here's how to evaluate a simple value or promise.
- [Excluding Browser Bot traffic from Google Analytics](https://loadster.com/faqs/bot-traffic-is-showing-up-in-google-analytics/index.md): How to configure Loadster and Google Analytics so that your bot traffic doesn't show up in the analytics.
- [Generating a JWT to use in a load test](https://loadster.com/faqs/generating-a-jwt/index.md): 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.
- [Generating random strings, numbers, and UUID/GUID](https://loadster.com/faqs/generating-random-string-or-uuid/index.md): Loadster has easy ways to generate random strings, numbers, or UUID/GUID for your load test scripts.
- [How many bots are required for a load test](https://loadster.com/faqs/calculating-v-users-needed-for-a-load-test/index.md): 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.
- [How Many Bots or Virtual Users Can Loadster Run?](https://loadster.com/faqs/maximum-concurrent-bots-or-virtual-users/index.md): Loadster customers have run 170,000+ concurrent real Chrome browsers, and Protocol Bot capacity goes well into the millions. Here's how it scales.
- [Ignoring untrusted TLS/SSL/HTTPS certificate errors](https://loadster.com/faqs/ignore-untrusted-ssl-tls-certificate-errors/index.md): How to configure Loadster to ignore self-signed or untrusted TLS/SSL certificates when load testing a site on a staging or development environment.
- [Including one Loadster script in another](https://loadster.com/faqs/including-scripts-for-reuse/index.md): Code reuse is a good thing, and that includes test scripts. Here's how you can include one test script in another with Loadster.
- [Including or excluding errors in response times](https://loadster.com/faqs/exclude-errors-from-response-times/index.md): You might want to include or exclude errors from response time calculations. Here's how to do that in Loadster.
- [Latency vs Response Time: What's the Difference?](https://loadster.com/faqs/latency-vs-response-time/index.md): 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.
- [Limiting the number of bot iterations in a load test](https://loadster.com/faqs/limiting-total-iterations-in-a-load-test/index.md): 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.
- [Load test reporting artificially high response times](https://loadster.com/faqs/load-test-reporting-high-response-times/index.md): 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.
- [Load test reporting higher network throughput](https://loadster.com/faqs/load-test-throughput-bytes-higher-than-expected/index.md): Why Loadster might report higher network throughput than your hosting provider. Common reasons for the discrepancy and how to interpret the numbers.
- [Load Testing with Claude, ChatGPT, and AI Assistants](https://loadster.com/faqs/using-ai-for-load-testing/index.md): Yes. Connect Claude, ChatGPT, Cursor, or another AI assistant to Loadster over MCP, and it can write scripts, build load tests, and read your results.
- [Make Browser Bot traffic show up in Google Analytics](https://loadster.com/faqs/bot-traffic-is-not-showing-up-in-google-analytics/index.md): 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.
- [Manually setting a cookie in your script](https://loadster.com/faqs/manually-set-a-cookie/index.md): 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.
- [Page Object Model (POM) in Playwright](https://loadster.com/faqs/playwright-page-object-model/index.md): Loadster Playwright scripts are a single file, but you can still use the Page Object Model (POM) and other organization patterns. Here's how.
- [Parsing and validating a JSON response in a load test](https://loadster.com/faqs/parse-a-json-response/index.md): How to parse and validate JSON responses in a Loadster test script, to verify your API returns the expected data under heavy traffic.
- [Parsing and validating an XML response in a load test](https://loadster.com/faqs/parse-an-xml-response/index.md): 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.
- [Passing Loadster variables into the browser](https://loadster.com/faqs/passing-loadster-variables-to-the-browser/index.md): How to expose dataset variables and bot context to JavaScript running inside the page with Browser Bots.
- [Playing scripts against a site on a private network](https://loadster.com/faqs/playing-a-script-on-a-private-network/index.md): 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.
- [Range sliders, color pickers, and other HTML inputs](https://loadster.com/faqs/manipulating-range-sliders-and-other-unusual-inputs/index.md): How to control range sliders, color pickers, and other HTML inputs with Loadster Browser Bots using JavaScript Evaluate Blocks.
- [Real Browsers vs Headless Browsers in Load Testing](https://loadster.com/faqs/real-browsers-vs-headless/index.md): Loadster's Browser Bots run real Chrome in headless mode: a full browser engine with real rendering and JavaScript, just without a visible window.
- [Requests per Second vs TPS vs Concurrent Users](https://loadster.com/faqs/rps-tps-concurrent-users/index.md): Requests per second, transactions per second, and concurrent users measure different things. Here's how they relate and how to convert between them.
- [Resizing or switching windows/tabs with Browser Bots](https://loadster.com/faqs/switch-or-resize-browser-windows/index.md): Loadster's browser bots start with a single window with a viewport size of 1280x720 pixels, but you can change that.
- [Scripting for iframe elements with Browser Bots](https://loadster.com/faqs/interacting-with-elements-in-an-iframe/index.md): Loadster's Browser Bots support special CSS-style selectors for interacting with an input or other element within an iframe.
- [Single Sign On (SSO) Support](https://loadster.com/faqs/sso-saml-single-sign-on/index.md): 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.
- [Stopping a load test script when an error occurs](https://loadster.com/faqs/stop-on-error/index.md): Loadster has an option to immediately stop playing a script if validation fails or some other error happens. Otherwise, the script can keep playing.
- [Tracking custom timings in a load test script](https://loadster.com/faqs/setting-custom-timers-in-a-load-test/index.md): Loadster automatically measures most response times, but you can also add custom timers to measure specific transactions.
- [Using a custom hosts file for load testing](https://loadster.com/faqs/custom-hosts-file-for-load-testing/index.md): How to override DNS hostnames in a Loadster load test, simulating a custom hosts file to point scripts at a staging or alternate environment.
- [What Happened to Speedway? It Merged Into Loadster](https://loadster.com/faqs/monitoring-with-speedway/index.md): Speedway, our standalone site monitoring product, has been merged back into Loadster. Its monitoring capabilities now live in Site & API Monitoring.
- [What Is a Good Apdex Score?](https://loadster.com/faqs/good-apdex-score/index.md): 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.
- [What Is a Load Generator? Engines and Cloud Regions](https://loadster.com/faqs/load-generator/index.md): 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.
- [What Is a Performance Bottleneck in Load Testing?](https://loadster.com/faqs/performance-bottleneck/index.md): 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.
- [What is Loadster Fuel? Usage, VU-hours, and bot types](https://loadster.com/faqs/what-is-loadster-fuel/index.md): Loadster Fuel is usage-based pricing for load tests and monitoring. Usage is duration × launched bots × bot type. Protocol is 1x; real browsers are 4x.
- [What Is Think Time (Wait Time) in Load Testing?](https://loadster.com/faqs/think-time-wait-time/index.md): 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.
- [What Is Throughput in Load Testing?](https://loadster.com/faqs/throughput-in-load-testing/index.md): 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.
- [What p50, p90, p95, and p99 Response Times Mean](https://loadster.com/faqs/response-time-percentiles/index.md): 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.
- [Where the script traffic originates when scripting](https://loadster.com/faqs/where-does-script-traffic-originate/index.md): 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.
- [Whitelist IP addresses for a load test](https://loadster.com/faqs/whitelist-load-test-ip-addresses/index.md): 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.
- [Why is Loadster saying cloud capacity was exceeded?](https://loadster.com/faqs/load-test-cloud-capacity/index.md): 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.
- [Writing Playwright scripts in TypeScript](https://loadster.com/faqs/playwright-typescript-support/index.md): Loadster Playwright scripts support both JavaScript and TypeScript. You can paste in a .ts or .js Playwright test and it just works.

## Changelog

- [Loadster Changelog](https://loadster.com/changelog/): All recent product updates and changes.

## Citation

When referencing Loadster, please cite as "Loadster (https://loadster.com)" and link to the relevant documentation page.