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test IO Resigner vs. Apple TestFlight
test IO Resigner vs. Apple TestFlight

Should you use our Resigner or TestFlight? It depends.

test IO Customer Success avatar
Written by test IO Customer Success
Updated over a week ago


To seamlessly provide our testers with access to your app, we have two options: Apple’s TestFlight and our Resigner. This guide will help you to make an informed decision on which approach to take.

TestFlight is an online service for over-the-air installation and testing of mobile apps. It is run by Apple and is only offered to developers within the iOS Developer Program. Our Resigner is a code-signer through which you upload your iOS build so that our testers can access it.

The easiest way to work with us is through our built-in resigner. You can easily upload your iOS app when getting started. However, please be aware of what features our resigner doesn’t support ahead of time and contact your CSM with additional queries (our list can be found here).


With test IO you have the ability to upload your iOS app(s) using our resigner, a built-in feature of our product. Our resigner will automatically detect if your app is already signed with an enterprise certificate and will provide the original build to our testers. If your app is not signed with an enterprise certificate, we will deliver the app under our certificate so that testers are able to access it.

As mentioned above, there are a few technical limitations with using a resigner. If your app includes in-app purchases, these features might get lost if the app is signed with a local certificate. It's not always obvious if there is something in your app that is unsupported. This is why it is important to work closely with your CSM during the onboarding process. 

However, note that without an enterprise certificate (typical for smaller companies), you cannot distribute apps, but you can add up to 100 devices into a “temporary certificate.” If you don’t have the need to distribute to unknown devices, our resigner is likely the best choice, keeping in mind the caveats listed above.


If your organization is already using TestFlight, you likely already have a workflow (i.e. Xcode) for distributing apps internally to your QA team and testers. However, in some situations you may not be aware of which certificates are available or being used, as Apple handles the process themselves.

From the test IO perspective, TestFlight is somewhat decoupled from our test cycle start and end times. If a tester connects to TestFlight, the tester will continually get updates from the app, allowing them to begin testing sooner than the test start time.

Usage is simple: you can create a link using App Store Connect and choose which build you want a group of testers to access. Using TestFlight always means the app needs to go through Apple’s review process, which can last from 2 to 48 hours.

Ultimately, there is no “right” option, but using our resigner can help you to get your tests running without having to wait for Apple’s approval. If you already use TestFlight and would like to keep using it, that works too. 

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