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Web app testing has no single official list of exactly eight types. The eight categories below are a practical way to plan checks, not mutually exclusive boxes: one browser journey can test a feature end to end and also serve as a regression test. Build your plan around what could fail, who uses the app, and what evidence will show that it works.
How to think about web app testing
Testing checks whether an application behaves as intended and helps reveal defects, compatibility problems, performance limits, security weaknesses, and barriers to use. Categories describe different testing goals or scopes, so they can overlap. For example, a form submission can be checked as a functional feature, tested across integrated services, exercised in a full browser journey, and rerun after a code change.
There is no canonical taxonomy that fixes the number at eight. This guide uses eight useful categories and treats accessibility and usability as essential concerns that cut across them.
Eight important types of web app testing
1. Unit testing
A unit test checks a small piece of code—such as a function or component—in isolation. It is useful during development for verifying focused behavior, such as whether a validation function accepts and rejects the right input. Unit tests do not, by themselves, prove that the complete application works in a browser.
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2. Integration testing
Integration tests check whether modules or services work correctly together. Examples include a form component communicating with its validation logic, or an application handling a response from an API. Add these checks at the boundaries where parts of the app interact; a module can pass its isolated tests while still failing when connected to another part.
3. Functional testing
Functional testing checks whether features behave according to their requirements. It can cover user interactions, forms, navigation, and links. Define the expected result first—for example, what message appears after a valid submission and what happens when required information is missing—then verify those outcomes.
4. End-to-end testing
End-to-end (E2E) tests exercise a complete user journey through the relevant parts of an app. A test might follow a user from opening a page through entering information and confirming a result. E2E checks can reveal failures between layers that isolated tests miss, but they are not a substitute for testing each smaller unit or integration point. Browser automation tools can run such checks; no single E2E method is universal.
5. Regression testing
Regression testing reruns checks after a fix or change to confirm that previously working behavior still works and that the update has not introduced new errors. A regression check may be a unit test, an integration test, a functional test, or a complete journey. Keep repeatable checks for important existing behavior and run the relevant ones after changes.
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6. Compatibility testing
Compatibility testing checks whether the app works across the browsers, operating systems, and devices used by its intended audience. Choose a realistic test matrix from that audience rather than assuming every possible environment must be covered. A desktop browser check cannot establish that a mobile layout or touch interaction works; test on relevant devices as well as in the environments your users rely on.
7. Performance testing
Performance testing measures responsiveness, speed, scalability, and stability under different workloads. The useful conditions depend on the app: consider both expected and heavier workloads, and pay attention to lower-spec mobile hardware when performance-sensitive behavior matters. A page that works functionally may still feel slow or become unstable under load.
8. Security testing
Security testing evaluates whether an app’s controls work and identifies weaknesses. The OWASP Web Security Testing Guide (WSTG) organizes coverage into areas including configuration, identity, authentication, authorization, session management, input validation, error handling, cryptography, business logic, client-side testing, and APIs. Use those domains to think beyond a single login check. The OWASP project page lists WSTG 4.2 as its latest versioned release and says version 5.0 is under development; check the OWASP project page for current status.
Accessibility and usability belong in the plan
Accessibility and usability are not optional extras just because they are outside this eight-item selection. Accessibility checks whether people with disabilities can perceive, operate, and understand the app. W3C says, “All WCAG 2 success criteria are written as testable criteria for objectively determining if content satisfies them.” Its guidance calls for both automated testing and human evaluation; passing success criteria alone does not guarantee that an app is usable for people with a wide variety of disabilities. See W3C’s Understanding Conformance.
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Usability testing examines how people actually use the app to complete tasks. Functional checks can often be automated, but usability assessment generally needs real participants. Include disabled participants when assessing accessibility and usability for those users. For evaluation planning, W3C’s WCAG Evaluation Methodology (WCAG-EM) 2.0 describes representative sampling and other evaluation factors.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Compare the categories by the failure you need to catch
| Category | Main target | Typical timing | What it can reveal |
|---|---|---|---|
| Unit | A small function, component, or code unit in isolation | During development | Incorrect behavior in a focused piece of code |
| Integration | Connected modules or services | When parts are combined and during ongoing checks | Failures at boundaries between components |
| Functional | A feature and its expected behavior | During development and before release | Interactions or outcomes that do not meet requirements |
| End-to-end | A complete user journey across relevant layers | In regular automated runs and before release | A broken flow that crosses multiple parts of the app |
| Regression | Previously working behavior after a change | After fixes and code changes | New errors or behavior that has stopped working |
| Compatibility | Selected browsers, operating systems, and devices | During validation against the audience’s environment | Environment-specific layout or behavior problems |
| Performance | Responsiveness, speed, scalability, and stability | During development and under relevant workloads | Slow responses, instability, or limits under load |
| Security | Security controls and app attack surfaces | Across development and security review | Weaknesses in areas such as access control, input handling, or sessions |
This is a planning comparison, not a required sequence. Select coverage based on the feature, its risks, and the environments people use.
A practical workflow for testing a web app
- Identify users and environments. Establish who the app serves and which browsers, operating systems, and devices they use. This defines a sensible compatibility matrix.
- Write acceptance criteria. State the expected visible behavior and functional outcomes before testing. Include keyboard and touch operation, readable text, and assistive technology behavior where relevant.
- Choose the appropriate test scopes. Match the checks to the feature and its risks: test focused logic, interactions between modules, user-facing behavior, complete journeys, and relevant security or performance concerns.
- Automate repeatable checks where useful. Run them regularly, such as after code changes or through continuous integration (CI), and record results. Automation is useful for repeatable verification, but does not replace human evaluation of usability or accessibility.
- Evaluate with people where needed. Combine automated checks with manual usability and accessibility evaluation. Include people with disabilities in studies when appropriate to the evaluation.
- Rerun relevant tests after a fix. Verify the repaired behavior and check for regressions in related or previously working parts of the app.
Choosing tools without treating examples as rankings
Google for Developers names Jest, Vitest, Cypress, Mocha, and Jasmine as frontend test frameworks, and Web Test Runner, Playwright, WebDriver, and Node.js’s Test Runner as runners. These are examples, not a ranked recommendation. MDN’s testing curriculum gives CircleCI and Travis CI as examples of CI services. Select tools by the language and browser environment they support, the test targets you need, whether they run in your CI workflow, and how maintainable their tests are. Automated tools still cannot replace evaluation with real people or checks on actual devices when those are needed.
For planning and terminology, see MDN’s testing guide, its guide to strategies for carrying out testing, and Google’s guidance on testing a content-driven web app frontend.
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