Using TestFlight Alongside Scarlet iOS
Two Powerful Tools for Getting More Apps on iPhone
When it comes to installing apps beyond the standard App Store catalog, iPhone users have more options than ever. Two of the most useful — and often underutilized in combination — are Apple’s own TestFlight and third-party tools like Scarlet iOS. While they serve overlapping purposes, they work through entirely different mechanisms and have distinct strengths. Using them together gives you access to the widest possible range of apps and beta software.
This guide explains both tools, how they work, where each one excels, and how to run them side by side on the same iPhone without conflicts.
What Is TestFlight?
TestFlight is Apple’s official beta testing platform, acquired from Burstly in 2014 and deeply integrated into iOS. It allows developers to distribute pre-release versions of their apps to testers before the apps are ready for the App Store. TestFlight comes in two tiers:
- Internal Testing: Up to 100 members of your App Store Connect team can test your app. No review required.
- External Testing: Up to 10,000 users who are not on your team can participate. Requires a basic beta review from Apple.
From the user’s perspective, TestFlight is extremely simple. You receive an invitation link from the developer, tap it on your iPhone, and the app installs just like an App Store app — automatically updating when new builds are published, showing clear versioning information, and collecting crash reports for the developer.
What Scarlet iOS Offers That TestFlight Does Not
TestFlight is limited to apps whose developers have specifically set up a TestFlight program. If a developer does not offer TestFlight access, you cannot use it to install their app. TestFlight also requires developer participation — the developer must actively invite you or publish a public link.
Scarlet iOS has no such restriction. If you have an IPA file — from any source — Scarlet can install it. This opens up:
- Apps that have been removed from the App Store
- Modified or patched versions of existing apps
- Apps from developers who do not offer TestFlight
- Older versions of apps
- Entirely unofficial apps that would never pass App Store review
Additionally, Scarlet iOS handles the signing process automatically, whereas TestFlight requires you to be on a developer’s explicit invite list. For a full picture of what Scarlet makes possible, see what Scarlet iOS is and how it works in 2026.
Running TestFlight and Scarlet iOS on the Same Device
The good news is that TestFlight and Scarlet iOS coexist peacefully on the same iPhone. There are no conflicts between them because they operate through entirely different installation channels. TestFlight apps have their own bundle IDs and use Apple’s native over-the-air installation system, while Scarlet iOS apps use enterprise or developer certificates through a separate pathway.
Potential Naming Collisions
The only scenario that can cause confusion is when you have both a TestFlight version and a Scarlet-installed version of the same app. iOS will treat these as the same app if they share a bundle ID, with the newer installation overwriting the older one. To run both versions simultaneously, use Scarlet iOS’s bundle ID override feature (available in Developer Mode) to change the bundle ID of one version, making iOS treat them as separate apps.
Use Cases for Combining TestFlight and Scarlet iOS
App Development Workflow
If you are developing an iOS app, you might use TestFlight to distribute builds to your team and select beta users, while using Scarlet iOS to install development builds directly from IPA exports for personal testing. This gives you two separate channels that do not interfere with each other.
Running Beta and Stable Versions Together
Some apps offer TestFlight betas alongside their stable App Store version. If you want to run the TestFlight beta alongside a modified or older version of the same app, install the TestFlight version normally and use Scarlet iOS with a different bundle ID for the alternative version.
Accessing Geographically Restricted Betas
Occasionally, TestFlight betas are limited to specific regions. If you live outside the eligible region, Scarlet iOS can often fill the gap by allowing installation of the same IPA regardless of your device’s region setting. This is one of Scarlet’s most useful practical advantages for international users.
How to Join TestFlight Betas
If you want to explore what TestFlight offers alongside Scarlet iOS, here is how to get started:
- Install the TestFlight app from the App Store if it is not already on your iPhone.
- Find a TestFlight beta link — developers often share these on their websites, social media, or through direct invitations.
- Tap the link on your iPhone. You will be taken to TestFlight with a prompt to accept the beta invitation.
- Tap Accept and then Install.
- The app installs immediately and will auto-update when the developer pushes new builds.
Managing Apps from Multiple Sources
When you have apps from the App Store, TestFlight, and Scarlet iOS all on one device, organization becomes important. Here are some tips:
- Use iPhone’s App Library to keep your home screen clean regardless of install source
- Check the TestFlight app periodically to see if any beta invitations have expired
- In Scarlet iOS, use the installed apps list to track which apps came from Scarlet and when their certificates expire
- If you notice an app behaving unexpectedly, check whether the version is from TestFlight or Scarlet, as they may be different builds
For managing updates across all your sideloaded apps efficiently, see our guide on automating app updates for sideloaded apps on iPhone.
Limitations of TestFlight to Keep in Mind
- Beta builds expire after 90 days — TestFlight automatically removes them from your device
- If a developer stops their TestFlight program, the app disappears from your device with no warning
- TestFlight apps are limited to the platforms the developer has configured
- TestFlight requires an Apple ID and a working internet connection for the initial install
Scarlet iOS does not have these limitations. Once an app is installed through Scarlet, it remains on your device as long as the certificate is valid, regardless of what the developer does.
Conclusion
TestFlight and Scarlet iOS are not competing tools — they are complementary. TestFlight gives you legitimate access to developer-sanctioned betas with excellent update management. Scarlet iOS gives you unrestricted access to any IPA file, including apps that TestFlight could never provide. Together, they cover virtually every app installation scenario you might encounter.
Get the best of both worlds. Download Scarlet iOS today and complement your TestFlight collection with unlimited sideloaded apps.