Software can look ready and still have problems that only appear when people start using it.
A feature may work in one scenario but fail in another. A new update may affect something that worked before. Performance may change under heavier traffic, or the software may behave differently across devices and browsers.
This is why software testing is an important part of software development.
Testing helps teams check that software works as expected, identify defects before they affect users, and understand the risks that remain before a release.
It is also not something that should happen only at the end of a project. Modern testing happens throughout development, combining manual testing, automation, and specialist testing where needed.
In this guide, we look at what software testing involves, the main types of testing, manual vs. automated testing, the testing process, and when outsourced software testing can make sense for a business.
What is Software Testing?
Software testing is the process of evaluating software to check that it meets its requirements and behaves as expected.
That includes confirming that features work correctly, but good testing also looks at what happens outside the expected user journey.
What happens when someone enters unexpected information? Does an integration still work when another system responds slowly? Does a new release affect existing functionality? Does the application behave consistently across the devices people actually use?
Depending on the software, testing may include:
- Checking that features work according to requirements
- Testing unusual inputs and edge cases
- Checking performance under different levels of load
- Testing across browsers, devices, and operating systems
- Checking integrations between different systems
- Confirming that changes have not broken existing functionality
- Identifying areas that may need specialist security testing
Software testing is often discussed alongside quality assurance testing, or QA.
The two are closely related, but they are not exactly the same.
Quality assurance is the broader approach to building quality into the way software is planned, developed, and delivered. Testing is one part of that process, focused on checking the software itself and identifying problems.
A strong QA approach includes both prevention and testing.
Why Software Testing Matters
The earlier a defect is found, the easier it is usually to deal with.
If an issue is discovered while a feature is still being developed, the team can investigate and fix it before other work depends on it.
The same issue discovered after release may involve customer impact, additional development work, support, data correction, or an urgent production fix.
The scale of poor software quality can be significant. The Consortium for Information & Software Quality estimated the cost of poor software quality in the United States at at least USD 2.41 trillion, with accumulated technical debt estimated at around USD 1.52 trillion in its Cost of Poor Software Quality report.
For an individual business, the numbers will obviously look very different, but the principle is the same.
Testing helps reduce the risk of releasing problems that could have been identified earlier. It also gives the project team better information when deciding whether software is ready to release.
Types of Software Testing
There is no single type of software testing that covers everything. Different testing methods answer different questions about the software.
| Test Type | What It Checks | Category |
| Functional | The software does what the requirements say | Functional |
| Regression | New changes have not broken existing features | Functional |
| Performance | Speed and stability under expected and peak load | Non-functional |
| Security | Resistance to attack and safe handling of data | Non-functional |
| Usability | The software is intuitive and easy to use | Non-functional |
| Compatibility | Correct behaviour across devices, browsers, and OS versions | Non-functional |
The right mix depends on the software.
A business application with complex integrations may need significant functional and integration testing. A mobile app may require broader device and operating-system coverage. A system handling sensitive information may require specialist security testing in addition to general QA.
Testing also happens at different levels during development:
- Unit testing checks individual pieces of code.
- Integration testing checks whether different components work together.
- System testing looks at the application as a whole.
- Acceptance testing checks whether the software meets the agreed business requirements.
A project may use several of these approaches rather than relying on one testing method.
Manual vs. Automated Testing
One common question is how much testing should be manual and how much should be automated.
In practice, the two approaches work best together.
| Area | Manual Testing | Automated Testing |
| Best For | Exploratory testing, usability, new features, and unusual scenarios | Regression testing, repetitive checks, and frequent releases |
| Speed | Depends on tester time | Can run quickly and repeatedly |
| Initial Setup | Relatively low | Requires time to build and configure |
| Maintenance | Test cases evolve with the product | Automated scripts need to be maintained |
| Human Judgment | Strong. Testers can explore and respond to unexpected behaviour | Limited to what the test has been designed to check |
Manual testing is useful when human judgment matters. A tester can explore a new feature, try unexpected actions, notice that a workflow is confusing, or investigate something that simply does not look right.
Automated testing is particularly useful when the same checks need to be repeated regularly. For example, a regression test suite can automatically check important existing functionality whenever the software changes.
Automation is also becoming more important as development teams release software more frequently.
The Capgemini World Quality Report referenced in the original content highlights growing investment in AI and automation within quality engineering.
AI can support activities such as test generation and analysis, but automated testing still needs clear objectives and appropriate review.
The practical question is not whether manual or automated testing is better. It is which parts of the testing process benefit from automation and where human judgment adds more value.
The Software Testing Process
A structured software testing process makes it easier to understand what has been tested, what has been found, and what still needs attention.
| Stage | What Happens |
| 1. Test Planning | Define what needs to be tested, the main risks, scope, tools, environments, and responsibilities |
| 2. Test Design | Create test cases and scenarios covering expected behaviour and edge cases |
| 3. Test Execution | Run manual and automated tests across the required environments |
| 4. Defect Reporting | Document issues clearly so developers can reproduce and investigate them |
| 5. Retesting & Regression | Confirm fixes and check that changes have not affected other functionality |
| 6. Reporting | Summarise what was tested, what was found, and what risks remain |
The process does not always happen as one sequence at the end of development.
On modern software projects, testing often happens continuously as features are designed and developed. This gives testers and developers the opportunity to discuss issues earlier rather than waiting until the application is almost ready to launch.
For a broader view of how testing fits into a software project, see What is Software Development? Process, Methods & How to Get It Right.
Software Testing in Agile and DevOps
Software development has become more iterative, and testing has changed with it.
In Agile and DevOps environments, teams may release changes regularly rather than waiting for one large release at the end of a project. Testing therefore needs to happen throughout delivery.
One common approach is shift-left testing, which means introducing testing earlier in the development process.
Another is continuous testing, where automated checks can run as part of the delivery pipeline whenever software changes.
This does not mean everything should be automated.
Automation can handle repeatable checks efficiently, while testers can spend more time exploring new functionality, investigating unexpected behaviour, and looking at areas where human judgment matters.
The aim is to make quality part of development rather than a separate activity that happens just before release.
In-House vs. Outsourced Software Testing
Businesses can build an internal QA team, use outsourced software testing, or combine the two.
| Area | In-House Testing | Outsourced Software Testing |
| Team | Permanent internal employees | QA professionals provided by an external partner |
| Capacity | Based on the size of the internal team | Can be adjusted around project needs |
| Skills | Depends on internal recruitment and available expertise | Can provide access to different testing capabilities |
| Management | Managed internally | Can be supported by the testing partner |
| Flexibility | Requires internal planning or recruitment to increase capacity | Easier to add capacity for specific projects or release periods |
| Often Suited To | Businesses with continuous and predictable testing demand | Businesses needing additional capacity, specialist expertise, or independent testing |
An internal team can work well when there is enough ongoing testing demand to support permanent QA staff.
Outsourcing can make sense when testing needs change between projects or development phases, or when an existing team needs additional expertise.
It can also complement an existing QA team rather than replace it.
When Does Outsourced Software Testing Make Sense?
Outsourced testing works best when the external QA team is integrated into the development process rather than receiving the finished product only at the end.
It can be useful when:
- Your developers need dedicated QA support
- Testing demand changes between project phases
- You need both manual and automated testing
- You want independent testing of software developed by another team
- You need additional capacity before an important release
- Building a full internal QA team is not practical
When choosing a software testing company, look beyond the hourly rate.
Ask who will actually work on the project, what testing experience they have, how manual and automated testing are handled, how defects are reported, and how the QA team will communicate with your developers.
Testing qualifications can also provide useful evidence of a team’s commitment to established testing practices.
Manao Software is an ISTQB Gold Partner, reflecting our investment in internationally recognised software testing standards and the continued professional development of our QA team.
For projects that need additional QA capacity, our Outsourced Software Testing service provides access to Manao testing professionals who can work alongside an existing development team.
What Does Software Testing Cost?
There is no standard cost for software testing.
The investment depends on the size and complexity of the software, the amount of coverage required, the balance between manual and automated testing, and whether QA is part of an ongoing development project or a separate engagement.
| Cost Factor | How It Affects Testing |
| Software Complexity | More features, workflows, integrations, and user roles generally require more testing |
| Testing Coverage | Broader coverage across functionality, devices, browsers, or environments increases effort |
| Manual vs. Automation | Automation requires upfront setup but can reduce repetitive effort over time |
| Release Frequency | Products with frequent releases usually need more continuous regression testing |
| Engagement Model | Testing may be included in a development project or provided as a dedicated QA engagement |
When testing is built into software development from the beginning, QA effort forms part of the overall project.
For dedicated or outsourced testing, pricing may instead depend on team size, duration, or the defined testing scope.
Automation also changes the cost structure. Building automated tests requires upfront effort, but those tests can then be run repeatedly as the software changes.
Cost should therefore be considered alongside risk.
The question is not simply how much testing costs, but what level of testing is appropriate for the software and the impact if an important issue reaches production.
How Manao Software Approaches Software Testing
Manao Software has more than 19 years of experience developing and testing custom software for businesses in Thailand and internationally.
As an ISTQB Gold Partner, our QA professionals work with internationally recognised software testing practices across manual and automated testing.
Testing is integrated into our delivery process rather than left until the end. Depending on the project, our QA team can work alongside Manao developers or provide independent testing for software developed by another team.
OMEGA, our AI-augmented software delivery platform, also supports selected parts of our testing workflow. AI can help improve efficiency, while experienced QA professionals remain responsible for reviewing results and making decisions that require human judgment.
Our approach is straightforward: test what matters, identify issues early, and communicate clearly about quality and risk.
Straight talk. Solid delivery.
Software Testing Is About Confidence, Not Just Finding Bugs
Finding defects is an important part of software testing, but it is not the whole purpose.
Good testing gives a development team better information. It shows what has been tested, what works, what still needs attention, and where risks remain.
Manual testing, automation, QA processes, and specialist testing all have a role depending on the software being built.
The right approach is the one that gives the team enough confidence to make a well-informed release decision without adding unnecessary process.
Need Additional Software Testing Support?
If your team needs additional QA capacity, Manao Software provides software testing services across manual and automated testing.
We can work alongside your existing development team, provide independent testing, or help add QA capacity where your project needs it.
