What is functional testing?

Functional testing checks that every feature of your software does what it is supposed to do. Testers compare the real behaviour with your requirements, user stories and business rules, using valid, invalid and edge-case inputs, and report anything that doesn’t match.

What is the difference between functional and non-functional testing?

Functional testing checks what the software does: features, workflows and business rules. Non-functional testing checks how well it does it: speed, security, usability, accessibility and compatibility. Most releases need both, so we plan them together.

Which types of functional testing do you offer?

Manual, smoke and sanity, integration, UI/UX, user acceptance, system, unit, exploratory, regression and end-to-end testing. We recommend the mix based on what you are releasing. The test mix finder on this page gives you a starting point.

Is functional testing manual or automated?

Both. New features, UI changes and exploratory work are best tested by people. Stable, repetitive checks such as regression suites are good candidates for automation. We usually start manually, then automate where it saves you time.

What is the difference between smoke testing and sanity testing?

Smoke testing is a quick check that a new build is stable enough to test at all: it loads, users can sign in and core journeys work. Sanity testing is a narrow check that a specific fix or change works, without retesting everything.

What do you need from us to get started?

Access to a test environment, test accounts and whatever requirements you have: user stories, designs, specifications or a walkthrough. If requirements are thin, we explore the product first and write them up as test cases for you to review.

Can you test without written requirements?

Yes. We run exploratory sessions, talk to your product owner and turn what we learn into test cases and a requirements traceability matrix. Many clients then use these as their first written specification.

Which tools do you use for functional testing?

We work in your tools. For test management we use TestRail, Zephyr, Xray, QMetry, PractiTest, Testsigma or Qase; Jira or Azure DevOps for bugs; Postman, Swagger and SoapUI for API checks; and BrowserStack, LambdaTest and emulators for browsers and devices.

How do you report bugs?

Every bug includes steps to reproduce, expected and actual results, screenshots or video, the environment, device or browser, severity and priority. We retest every fix and track each bug to closure in your tracker.

How long does functional testing take?

It depends on the size of your product and the mix of testing types. Smoke checks are quick; a full test cycle for a new product takes longer. After a short discovery we give you an estimate broken down by testing type and platform.

Do you test on real devices and browsers?

Yes. We test on the browsers, devices and operating systems your users have, using real devices and BrowserStack, so issues that only appear on a particular device are caught.

Can your testers join our sprints?

Yes. Our testers join your stand-ups, planning and tools, test stories as soon as they are ready and run regression before each release. A dedicated QA team or staff augmentation suits this best.

How do you keep our product and data secure?

We sign your NDA before any access, use test accounts and synthetic data by default, and only work in the environments you approve.

How do you write test cases?

We write test cases from your requirements and acceptance criteria, covering valid, invalid and boundary inputs, validation, empty states and user roles and permissions. If requirements are missing, we run exploratory sessions and talk to your product owner first, then turn what we learn into test cases and a requirements traceability matrix.

How do we get started?

Book a call or send the form on this page. We start with a free one-week proof of concept, so you can see our test cases and bug reports on your own product before you commit.

Functional Testing Services

Leverage our expertise in functional testing to ensure impeccable functionality for every user, regardless of the platform.

In-house QA engineers check every feature, workflow and business rule against your requirements, on web, mobile, API, desktop and cloud, and report each bug with the steps to reproduce it.

Get in touch Find your test mix

10 functional testing types
Web, mobile, API, desktop and cloud
Works in your Jira and test tools
Free one-week POC

Jump to a testing type

Manual TestingHuman-led Smoke & Sanity TestingEvery build Integration TestingModules together UI/UX TestingLook and behaviour User Acceptance TestingBusiness sign-off System TestingThe whole product Unit TestingCode level Exploratory TestingBeyond the script Regression TestingAfter every change End-to-End TestingWhole journeys

[ Functional testing as a service ]

Our functional testing service has a lot to offer

We offer Functional Testing as a Service, ensuring the reliability, functionality, and user-friendliness of your software across web browsers, mobile devices, and desktops. Our functional testing service uses advanced methodologies for comprehensive quality assurance, ensuring a consistent and exceptional user experience on diverse platforms.

Guarantee a seamless experience on every platform your software supports.
Eliminate bugs early in the development cycle for all platforms.
Bridge the gap between your development team and user expectations.
Deliver high-quality software that meets all user needs and gives you better ROI.

Early Detection of Defects

By detecting defects early, our testing approach helps prevent expensive fixes and risks in later stages.

Enhanced Software Quality

By rigorously testing all functional aspects, we ensure that your software is reliable and performs consistently under expected conditions.

Improved User Experience

We focus on correct feature functionality, enhancing user satisfaction and ensuring a seamless and enjoyable experience.

Validates Business Rules

We validate business rules through functional testing, ensuring the software meets organizational objectives and needs.

Compliance with Specifications

Validates application adherence to technical specifications and regulatory standards, ensuring user expectations and compliance.

Long-term Application Success

Confirms that current functionality is reliable and solid, paving the way for future updates and long-term success.

[ 10 functional testing types ]

Beyond Bugs: Ensuring Your Software Works as Intended

QAonTOP utilizes different functional testing methods to find system bugs and errors, choosing the most effective approach for each testing situation. Here is what each one covers, when you need it and what you receive.

Manual Testing

Human-led

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Skilled testers use your product the way real users do, step by step, against written test cases and their own judgement.

What we check

Every feature checked against requirements and acceptance criteria
Valid, invalid and boundary inputs
Error messages, validation and empty states
User roles and permissions

When you need it

New features, frequent UI changes and anything that needs human judgement.

You getTest cases and execution results

Smoke & Sanity Testing

Every build

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Fast checks on every new build. Smoke testing confirms a build is stable enough to test; sanity testing confirms a specific fix or change works.

What we check

App loads, users can sign in and core journeys work
Critical paths checked as soon as a build lands
Bug fixes confirmed on the new build
A clear go or no-go for deeper testing

When you need it

Every build, hotfix and deployment to a new environment.

You getBuild verification checklistGo / no-go report

Integration Testing

Modules together

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Verifying whether individual components communicate and work effectively as a whole.

What we check

Data passed correctly between modules and services
Payments, email, SSO, CRM and other third parties
API responses shown correctly in the UI
Behaviour when a dependency is slow or down

When you need it

New integrations, microservices and any change to shared data.

You getIntegration test matrixDefect reports

UI/UX Testing

Look and behaviour

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Ensuring that your digital product exhibits superior appearance and user-friendly design.

What we check

Screens match the approved designs
Buttons, forms, menus and states behave consistently
Layouts hold up on every screen size
Labels, copy and navigation make sense

When you need it

Redesigns, new screens and before demos or launches.

You getUI defect log with screenshots against the design

User Acceptance Testing

Business sign-off

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Validating software from the user’s perspective to ensure seamless usability.

What we check

Business scenarios written with your stakeholders
Real workflows from start to finish
Business rules, calculations and outputs
Sign-off criteria agreed before testing starts

When you need it

Before go-live, a client hand-over or a contract milestone.

You getUAT scenarios and resultsSign-off record

System Testing

The whole product

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Complete system testing ensures every component works together to meet specified business requirements.

What we check

The full product tested in a production-like environment
Every functional requirement traced to a test
Data flows, reports and notifications
Configuration and environment settings

When you need it

After integration testing, before UAT or release.

You getRequirements traceability matrixSystem test report

Unit Testing

Code level

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Improving the smallest building blocks of your application code, ensuring each piece functions well.

What we check

Existing unit tests reviewed for gaps
Edge cases and error handling your tests miss
Coverage reviewed with your developers
Test cases agreed before code is written

When you need it

When defects keep slipping out of new code.

You getUnit test gap reviewCoverage notes

Exploratory Testing

Beyond the script

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Dynamic exploration to uncover software issues and enhance quality.

What we check

Time-boxed sessions with a clear goal
Unusual paths, interruptions and odd data
Areas where written tests are thin
Findings turned into new test cases

When you need it

New features, tight deadlines and before big releases.

You getSession notesBugs found and new test ideas

Regression Testing

After every change

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Ensuring that changes or updates haven’t inadvertently affected functional aspects.

What we check

A regression suite built around your core features
Risk-based selection for each release
Full regression before major releases
Stable checks flagged for automation

When you need it

Every release, upgrade or major bug fix.

You getRegression suite you ownRelease test report

End-to-End Testing

Whole journeys

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Mapping user flows to ensure seamless process execution without disruptions.

What we check

Complete journeys, such as sign-up to purchase
Across web, mobile, APIs and emails
Test payments, real data shapes and third parties
The same journey for every user role

When you need it

Before launches and after changes to key journeys.

You getEnd-to-end journey mapJourney results

[ Platforms ]

Our testing supports different platforms

Functional testing adapts to where your product runs. Each platform has its own risks, so we start with those, then cover the rest.

Web applications

Enhancing functionality across diverse web browsers, devices, and operating systems.

Mobile applications

Testing software across a diverse range of mobile devices running on various systems (iOS, Android).

API & Web Services

Ensuring APIs deliver accurate and consistent data in response to various requests.

Desktop Applications

Ensuring seamless desktop operations through core functionality testing on diverse platforms, across systems like Windows and Linux.

Databases

Integration validation to ensure your software interacts seamlessly with the underlying database.

Cloud Services

Upgrades applications with cutting-edge cloud services and frameworks for effective testing, with automatic updates, enhanced security features and seamless integration.

AI & LLM products

The app around the model, from sign-in and chat to history, uploads and settings, tested like any other product.

A process built on solid foundation

We handle all aspects of functional testing, from creating an optimized test plan to post-production support. Our user-centric approach ensures continuous value improvement, complete traceability of requirements, and detailed reporting with customized dashboards for effective test management.

Step 1 of 6
Requirements Traceability

Every requirement and user story mapped to test conditions, so nothing goes untested.

You getRequirements traceability matrix
Step 2 of 6
Test Strategy Design

Scope, risks, testing types, environments, test data and entry and exit criteria agreed with you.

You getTest strategy & test plan
Step 3 of 6
Test Case Management

Test cases written, reviewed and organised in your test management tool, ready for every release.

You getReviewed test casesTest data sets
Step 4 of 6
Defect Report and Tracking

Every bug logged with steps, expected and actual results, screenshots or video and severity, then retested after the fix.

You getBug reports in your trackerDaily or weekly status
Step 5 of 6
Root Cause Analysis

Defects grouped by cause and module, so your team fixes the source, not just the symptom.

You getRoot cause summary
Step 6 of 6
Test Summary Report

Coverage, results, open risks and a clear go or no-go recommendation for the release.

You getTest summary reportRelease sign-off

Free one-week POCSee our test cases and bug reports on your product before you commit.
Your tools, your workflowWe work in your Jira, test management tool and team chat.
NDA before accessWe sign your NDA first and use test accounts and synthetic data by default.

[ Tools ]

The tools behind our functional and manual testing

31 tools across six jobs. We work in the ones your team already uses, or set up the right ones for you. Automation frameworks are covered on our automated testing page.