What are the top 5 testing tools?

This post covers seven tools: Playwright, Cypress and Selenium for the browser, and Postman, REST Assured, Step CI and Stresseur for the API. Which five fit a team depends on whether the risk sits in the screen or in the API behind it.

Can one tool cover both browser and API end-to-end tests?

Yes, in part. Playwright can send requests to the server directly without loading a page. A team can write both layers in one tool, with the API steps written by hand.

Do I need a browser tool if I have API flow tests?

Yes, for what only a browser sees. Layout, client-side logic and cross-browser behavior never reach the API. Keep a small set of browser tests for those and let API flows carry the journey logic.

End-to-End Testing Tools: Browser and API

End-to-end testing tools fall into two groups: browser tools that drive the UI, and API tools that run the same journey as requests. Most teams need one of each. This list names the common choices in both groups, says what each does better, and stays neutral about where each one stops.

How we picked these end-to-end testing tools

The end-to-end testing guide covers what E2E means and why suites get slow. This post goes one level down and compares tools. Every tool here can run a full user journey, runs in CI, and is documented in public. Each entry has the same three fields: what it is, what it does better, and where it stops. The facts come from each tool’s own documentation, linked in the entry.

What to look for in an end-to-end testing tool

Five questions sort the field faster than a feature matrix.

Which layer does the risk sit in? A broken button needs a browser tool. A wrong price or a missing permission check needs an API tool.
Which language does your team already write? A test nobody can read gets deleted. Match the tool to the language of the codebase.
How does it run in CI? A tool that cannot run headless on a pull request will end up as a nightly job nobody reads.
How does it fail? A message that names the step and the server’s answer shortens the fix. A message that says an element was not found sends you to the page first.
How much data setup does it need? Every end-to-end test needs its own fresh data. A tool that makes that easy saves more time than one with a longer feature list.

Browser-layer end-to-end testing tools

Browser tools drive a real browser and check what the user sees. They are the only layer that tests layout and client-side behavior.

Playwright

Playwright supports Chromium, WebKit and Firefox on Windows, Linux and macOS. It bundles a test runner, assertions, isolation and parallelization.

Better at: cross-browser coverage and mobile emulation. It offers native mobile emulation for Chrome on Android and Mobile Safari. By default, tests run headless and in parallel across the three browser engines.

Pick it when: you want one runner for several browsers and for mobile emulation, with the assertions and isolation already built in.

Where it stops: it checks the journey through the UI, so it sees nothing the page does not show.

Cypress

Cypress runs in the same run loop as your application. Its architecture does not use Selenium or WebDriver.

Better at: debugging while you write. You can hover over commands in the Command Log to see what happened at each step. That makes a failing test easy to read.

Pick it when: the front end is JavaScript and you want quick feedback while you write a test.

Where it stops: it runs tests in Firefox and Chrome-family browsers, including Edge. It does not support controlling more than one open browser at a time. The only language it will support is JavaScript.

Selenium

Selenium WebDriver drives a browser natively, as a user would, either locally or on a remote machine using the Selenium server. WebDriver is a W3C Recommendation.

Better at: remote and distributed runs. Selenium Grid runs tests in parallel across multiple machines.

Pick it when: you already run Selenium Grid, or need tests to run on a remote machine.

Where it stops: it drives browsers; API-level steps need another tool.

API-layer end-to-end testing tools

API tools send the requests your UI would send, in order, and check each response. There is no page to load, so they skip timing and selector problems.

Playwright’s request API

Playwright can send requests to the server directly, without loading a page. Its documentation lists preparing server-side state before visiting the web app as a use.

Better at: staying in one tool. A team already on Playwright can write API steps beside browser tests.

Where it stops: you write every step by hand. Our post on Playwright API testing vs a recorded flow covers that trade.

Postman

Postman lets you send some or all of the requests in a collection with the Collection Runner, in the order you choose. The Postman CLI can run collection runs in a CI/CD pipeline.

Better at: trying out an API by hand and sharing collections across a team.

Where it stops: it works from collections of requests and does not test the screen.

REST Assured

REST Assured exists because testing and validating REST services in Java is harder than in languages such as Ruby and Groovy.

Better at: Java teams who want API tests in the same language and build as the service.

Where it stops: it is a Java library, so it fits teams that already work in Java.

Step CI

Step CI is an open-source API quality assurance framework. It covers REST, GraphQL, gRPC, tRPC and SOAP, so different API types can share one workflow.

Better at: mixed API styles in one declarative workflow.

Where it stops: it tests APIs only, not the screen. Our comparison of Postman and Step CI in CI shows the two API tools side by side.

Stresseur

Stresseur records how an API is really used during development, turns those flows into YAML tests, and runs them in CI on every pull request. Flows live in the repo under api-tests/. The recorder also captures page loads and form posts, so apps that serve HTML from the server work. The npx stresseur init quickstart finds the app, records it in a fresh browser window and generates the flows. Generated flows send fresh sign-up values on each run and check each answer as well as the status.

Better at: journeys you would otherwise write by hand, and checks you want on every pull request.

Where it stops: it tests the API, not the screen. It does not see layout or client-side logic, so keep browser tests for those. The Stresseur vs Playwright page puts the two side by side.

End-to-end testing tools at a glance

Tool	Layer	Better at
Playwright	Browser, plus API requests	Cross-browser runs and mobile emulation
Cypress	Browser	Debugging with a readable command log
Selenium	Browser	Remote runs and Selenium Grid
Postman	API	Trying out an API and sharing collections
REST Assured	API	Java teams
Step CI	API	Mixed API types in one workflow
Stresseur	API	Flows recorded from real use, run on every pull request

Which end-to-end testing tool to choose

Choose by where the risk is. If a bug would live in the screen, pick a browser tool and write its tests with user-facing locators. If it would live in the logic behind the screen, write API flows and run them on every pull request. Most teams end up with a few browser tests on top of a larger set of API flows.

A workable setup looks like this:

Write one browser test per critical journey, such as login and checkout, and keep each one short.
Write API flows for the same journeys and for their edge cases: bad input, missing fields and expired tokens.
Run the API flows on every pull request and make them a required check.
Run the browser tests on every pull request too if the time budget allows, and otherwise before a release.
When a browser test flakes on a check that does not need the screen, move that check into an API flow.

The split keeps the slow, fragile layer small and the fast, precise layer large.

Two more reads help here. Flaky tests: causes and fixes explains why browser suites wobble and what to move down a layer. Choosing an API testing framework goes deeper on the API side.

Browser tools see the screen and API tools see the journey’s logic. Pick one of each, keep the browser set small, and let the API flows carry the volume.