How to Test a Website: Main Types of Website Testing

A website has two jobs. It must be easy and pleasant for visitors to use, and it must work for the business: bring enquiries, sales or bookings. Website development does not end when the last page is built. Website testing checks both jobs, before launch and after every major change. This guide explains the main types of testing, what each one checks and how to test a website step by step.

Quality Assurance (QA) and Quality Control (QC) are two connected parts of keeping a website working properly. QA is preventive: it sets the processes, standards and reviews at each stage of development so that fewer defects appear in the first place. QC is part of QA and checks the finished product for defects, to make sure it meets the requirements agreed with the owner.

In short, QA works with the process and aims to prevent bugs while the website is being built, and QC works with the result and finds and fixes what went wrong. Used together, they give a complete picture of quality.

To test a website properly, testers use several types of testing. Their checklist usually covers each part of the site in turn, as described below.

Functional testing checks that every feature of the website works as intended. A checklist usually includes:

• forms, such as contact, quote and newsletter forms, and the emails they send;
• internal links and buttons, with no broken links or 404 errors;
• registration, login and password reset pages;
• the purchase journey: adding to the basket, checkout, payment, delivery options and order confirmation;
• editing data the user has entered, such as account details or the basket.

To make functional testing as complete as possible, testers combine several techniques.

1. Ad hoc testing. A quick, unplanned check of the main functions without preparation. It finds obvious problems in key features early.
2. Exploratory testing. The tester learns how the product works while testing it and plans the next checks based on what they find.
3. Negative testing. The tester deliberately enters wrong data, such as letters in a phone number field, empty required fields or an expired card, to see whether the site handles errors and shows clear messages to the user.
4. Equivalence partitioning. Possible inputs are split into groups that should behave the same way, for example quantities from 1 to 10, zero and more than 10, and one value from each group is tested. This covers every case with fewer tests.

Load testing shows how many visitors and how much data your website can handle before it slows down or fails. It is especially important before an advertising campaign, a sale or a seasonal peak, when traffic can rise sharply in a short time.

Testers use tools that simulate many users at once and measure how the website behaves in different conditions:

• a growing database, such as more products or orders;
• a large number of visitors at the same time;
• the highest load you expect (load testing);
• load beyond the planned limits, to find the breaking point (stress testing);
• long periods of heavy use (endurance testing).

The results show page load times, server response times, how many requests the site can handle and how much room it has to grow. Speed for a single visitor is a separate check: Google’s Core Web Vitals measure loading (Largest Contentful Paint), responsiveness (Interaction to Next Paint) and visual stability (Cumulative Layout Shift).

Usability testing checks how easily real people can find information and complete tasks on your website, such as finding a service, requesting a quote or placing an order. It is the core of user experience (UX) work. Its goals are to:

1. Assess how convenient the website is for visitors.
2. Find and remove elements that get in the way.
3. Check that the navigation is simple and clear.
4. Understand how satisfied users are and where they get stuck.

A basic checklist includes:

• Navigation. All menus and buttons work, and the user can reach the main menu from any page;
• Ease of use. The structure is easy to understand, pages are free of clutter and the main calls to action are easy to see.

Usability testing methods fall into two groups:

1. Moderated testing. A moderator watches participants complete tasks, in a lab or in the same room, asks questions and notes their behaviour, reactions and impressions.
2. Unmoderated remote testing. Participants complete the tasks on their own devices without a moderator, and testing tools record their screens and actions for specialists to analyse later. On a live website, heatmaps, session recordings and A/B testing add data from real visitors. For an independent review, see our website usability audit.

Testing the Website Design (UI)

UI testing is part of usability testing. It checks that the visual parts of the website, such as layouts, colours, fonts, buttons and icons, match the approved design.

Design testing also looks at whether the graphics support the brand and the main message of the site. Testers check the colour scheme, contrast, style, font sizes and font types, as well as whether the interface follows common design conventions. If you are planning a redesign, see our web design services.

Developers, designers and marketers can all assess the design, but people from your target audience are just as useful. They are not experts, so they show how attractive and clear the site looks to real customers.

This stage checks that the website works on different devices, screen sizes and browsers. With responsive design the layout adapts to each screen, and testing confirms that it really does. We explain the approach in more detail in our article on responsive web design.

Standard layout testing checks:

• that the main blocks display correctly;
• that the pages match the approved design;
• that the layout works at different screen widths without distortion;
• that other language versions display correctly;
• that links, buttons and icons are easy to click or tap;
• that images have alt text, which is shown if the images do not load;
• that blocks keep their shape when longer text is added;
• that key functions still work if JavaScript fails to load;
• that the site meets web accessibility basics, such as keyboard navigation, readable contrast and support for screen readers, in line with WCAG 2.2.

Cross-browser testing then checks that the website works normally in different conditions:

1. On phones, tablets, laptops and desktop computers of different models.
2. In the current versions of the main browsers: Chrome, Safari, Edge, Firefox and Samsung Internet.
3. At different screen resolutions and orientations.
4. On different operating systems: Windows, macOS, iOS, Android and Linux.

Security testing checks how well the website resists attacks and protects data. A widely used reference is the OWASP Top 10, a list of the most critical security risks for web applications. Security testing has three main goals:

• confidentiality. Personal data and closed sections are available only to people with the right access level;
• integrity. Data cannot be changed or deleted without permission, and unauthorised changes can be detected;
• availability. The website and its data are available to users when they need them and can be restored from backups after an attack or failure.

A security check usually covers:

1. HTTPS on every page, a valid SSL certificate and no errors when the browser and the server connect.
2. CAPTCHA or other spam protection on forms, and whether it displays and works correctly.
3. No access to closed pages, such as the admin area or customer accounts, without logging in.
4. Logging of errors and attempts to break in.
5. Automatic logout after a period of inactivity.
6. Secure registration, login and password reset, including strong passwords and a limit on failed login attempts.

Complete website testing covers functionality, performance, usability, design, cross-browser behaviour and security, whether the site is new or has been live for years. A fault in one area is often caused by a problem in another, so test the whole site before launch and after major updates. If you are planning a new website or a rebuild, contact us.