What is BrowserStack Load Testing?

BrowserStack Load Testing is a cloud-based platform that enables you to run large-scale load tests across browsers, APIs, or both combined. You can simulate real user traffic by executing your existing functional test scripts (Playwright or Selenium) at scale, or target backend APIs with JMeter tests, or combine the two for hybrid load scenarios. This gives you complete performance insights across frontend, backend, and network layers without needing to manage any infrastructure.

What is browser-driven load testing?

Browser-driven load testing is a type of load testing where real browser instances simulate actual user behavior by loading web pages and interacting with UI elements just as a human would. It provides end-to-end visibility into how users experience your application.

What is API load testing?

API load testing focuses on sending requests directly to your backend endpoints, bypassing the UI. It helps measure backend scalability, latency, and error handling under heavy load, ensuring your services can support the demand.

What is hybrid load testing?

Hybrid load testing combines the strengths of browser-driven and API load testing. Using JMeter scripts for API load and Playwright/Selenium scripts for browser load, you can simulate realistic traffic patterns where both the frontend and backend are stressed together. This approach ensures you catch issues that appear only when the entire system is under load.

Benefits of browser, API, and hybrid load testing

End-to-end performance visibility

• Browser-driven tests capture page rendering, JS execution, and backend network calls.
• API tests validate raw backend performance and throughput.
• Hybrid tests reveal how frontend and backend bottlenecks interact under real-world traffic.

Supports modern web app architectures

• Crucial for SPAs and microservices-based apps where frontend complexity is high and APIs alone don’t tell the whole story.

How does BrowserStack Load Testing work?

Reuse test scripts

• Use Playwright/Selenium scripts for browser load.
• Use JMeter scripts for API load.
• Combine both for hybrid scenarios.

Configure load profile

• Define number of concurrent virtual users, geo-locations, duration etc.

Execute tests at scale

• BrowserStack spins up real browsers and/or API workers across its cloud infrastructure.

Monitor performance metrics in real-time

• Frontend: Core Web Vitals, rendering times, JS execution.
• Backend: Response times, throughput, error rates.

Analyze and optimize

• Identify whether issues lie in frontend code, backend performance, or their interaction.

Why use BrowserStack Load Testing?

• Reuses existing test scripts: Scale Playwright/Selenium and JMeter tests instead of creating new ones.
• Full-stack performance visibility: Measure frontend and backend performance individually or together.
• Zero infrastructure overhead: Cloud-based browser provisioning, scaling, and orchestration.
• Geo-distributed testing: Simulate traffic from multiple regions for real-world accuracy.
• CI/CD ready: Plug into Jenkins, GitHub Actions, GitLab, and more for automated performance checks.