Mobile and web penetration testing: why one usually takes more time and effort

On the surface, a mobile app and a web app might deliver the same service. Same features, same users, same outcomes. So why does testing one often cost more than the other?

The short answer: a mobile app isn’t just another front end - it’s a different environment entirely. If you’re new to security testing, it’s worth understanding what penetration testing is and how it applies across different platforms.

Multiple platforms increase complexity

Web application penetration testing usually focuses on a single interface accessed through a browser. Once we have access through a URL and accounts, testing can start relatively quickly.

Mobile apps are different. Most clients need their apps to work on both iOS and Android. While there are shared principles, each platform has its own behaviour, security features, and potential risks. That means both need to be tested properly, rather than assuming what works on one will work on the other. Testing multiple platforms naturally takes more time.

Setup and planning take extra time

Mobile pen testing involves more preparation than web application testing. We often need access to different app builds for iOS and Android and consider different operating systems (OS) because apps can behave differently depending on the system.

There’s also a choice between using emulators, which simulate devices in software, or physical devices, which give a more accurate view of how the app behaves in the real world. Some apps may need to be sideloaded - installed outside of the app store - before testing can begin.

All of this introduces additional steps that can extend the setup phase. Timelines can increase further when clients need to coordinate across teams, provide multiple builds, or support a range of devices and OS versions. The way testing is carried out can also vary depending on the balance between manual and automated pen testing approaches.

How mobile apps interact with devices

A web app lives in a browser, but a mobile app interacts directly with the device it’s installed on. That includes file storage, biometric authentication (Face ID, fingerprint), permissions, notifications, and local caching.

Mobile apps may also allow offline functionality, introducing additional considerations such as how data is stored locally and how it synchronises when online. Each of these is a potential point of vulnerability and needs to be assessed as part of the mobile app penetration testing process, often alongside supporting activities like vulnerability scanning.

Advanced testing in mobile app pen tests

Mobile app penetration testing also requires specialised skills. Testers might perform reverse engineering and binary analysis, decompiling the app’s binary file to check for hardcoded secrets, insecure code, or signs of tampering.

Mobile apps also rely heavily on API backends, so both the client-side app and the server-side API must be tested. This ensures data is handled securely, responses behave correctly under attack, and no sensitive information is exposed.

Alongside this, we follow the MASVS - the Mobile Application Security Verification Standard. MASVS is like the OWASP Top 10 for web, but with much broader coverage of platform-specific risks and security controls. It includes around 130 security checks, ensuring testing is thorough across both iOS and Android. Naturally, this adds to the effort compared with a standard web test.

Additional security controls require attention

Mobile apps often include protections such as certificate pinning or root/jailbreak detection. These are critical security measures but require careful assessment. In some cases, testers need to safely bypass these controls to complete testing, which adds additional effort compared with standard web application pen testing.

Mobile pen testing isn't always longer - but generally is

It’s worth emphasising that mobile application penetration testing doesn’t always take longer than web testing - it generally does. A highly complex web application can take as long as a medium-complexity mobile app.

The main reasons mobile testing usually takes longer are the need to assess both iOS and Android, the extra setup and planning required, and the broader interactions with the device.

The key difference

Web app testing focuses on what’s exposed through the browser. Mobile app testing includes that same backend, plus how the app behaves on a real device, how it stores data, interacts with the OS, and communicates securely with its API.

That extra depth - multiple platforms, device interaction, reverse engineering, API testing, and offline considerations - is what usually drives the difference in effort and cost.

About Zoonou

We’re a digital QA company and security testing company, helping organisations build confidence in their web and mobile applications - from penetration testing and vulnerability assessment through to broader quality assurance.