"Untrusted Developer" on iPhone: how to trust your own app (2026)

By Sigsten Gustavii· 9 October 2026· Updated 26 October 2026· 8 min read

You built an app, installed it on your iPhone, tapped the icon, and got a message saying the developer is untrusted. It is alarming the time you see it, especially when the developer is you. The good news: it is a one-time setting, it takes about thirty seconds, and nothing is wrong with the app.

This guide explains why iOS shows the message, the exact steps to trust your app, and what to do when the steps do not seem to work.

Why your iPhone says "Untrusted Developer"

Every app on an iPhone is signed: it carries a certificate that says who made it. Apps from the App Store and TestFlight are signed in a way iOS already trusts. An app installed directly, with your own Apple ID or by a company outside the App Store, is signed by someone your iPhone has not been told about yet.

So iOS asks you, once, whether you trust that signer on this phone. Until you say yes, apps from that signer do not open. That is all the message means. It is not a virus warning, and it does not mean the app is broken.

How to trust your own app, step by step

Step 1: Open VPN & Device Management

Open Settings, tap General, then scroll down to VPN & Device Management. On older iOS versions the same screen is called Profiles & Device Management.

Step 2: Find the developer

Under the heading Developer App (or Enterprise App, for apps from a company), you will see an entry for the signer. For an app you installed with your own Apple ID, it names your Apple ID.

Step 3: Tap Trust

Tap the entry, then tap Trust and confirm in the alert. The screen now lists the apps from that developer as verified.

Step 4: Open the app

Go back to the home screen and open the app. It starts normally. You will not be asked again for apps signed by the same Apple ID on this phone.

If the app still will not open

Trusting the developer is one of two settings an app installed this way needs. The other is Developer Mode, a switch Apple added in iOS 16. If the app still refuses to open, check them in this order:

1. Developer Mode: Settings, Privacy & Security, Developer Mode, on. It needs a restart and your passcode. Our guide to turning on Developer Mode has the steps.
2. Trust: Settings, General, VPN & Device Management, your Apple ID, Trust.
3. The seven days: an app signed with a free Apple ID runs for seven days. After that it needs signing again. Borel Companion renews it while it runs, or press Reinstall.
4. Three apps: a free Apple ID can have three such apps on a device at once. Remove one you no longer use.

Why the message can come back, and how to avoid it

Trust belongs to the signer on this phone. It can disappear when every app from that signer is removed, because there is nothing left to trust. If you delete your only personal app and install another one later, you may see the message again and simply trust it again.

The seven-day limit is a different thing that people mix up with it. An app signed with a free Apple ID expires after seven days, and then it will not open until it is signed again. That is not a trust problem; it is Apple's limit for free accounts. Companion signs each app again while it runs, so in practice the app keeps working.

How Borel apps get on your iPhone

Borel writes your app in native Swift and builds it with Xcode on its own Mac. You try it in the iPhone simulator in your browser, which needs none of these settings. When you want the real app on your phone, Borel Companion, a small app for Windows and Mac, signs it with your Apple ID and installs it: over a cable when you set it up, then over Wi-Fi. The download is free, and installing with it comes with Borel Pro, from $20 a month.

Your Apple ID stays on your computer and is never sent to Borel. Because Companion signs with your Apple ID, the developer you trust on the phone is you.

If you would rather never see these settings, use TestFlight or the App Store instead. Those routes need Apple's Developer Program, $99 a year, and Borel Pro for publishing; read TestFlight explained to compare.

Untrusted Developer vs the other messages you might see

Apps you install yourself can meet a few different messages, and each has its own fix. It saves time to know which one you are looking at before you start changing settings:

• "Untrusted Developer" means the iPhone has not been told to trust the signer. Trust it under VPN & Device Management, as above.
• "Untrusted Enterprise Developer" is the same question for an app a company distributes outside the App Store. Only trust it if you know the company.
• The app does not open and nothing appears usually means Developer Mode is off. Turn it on under Privacy & Security.
• "This app is no longer available" or the app closes at once after a week usually means its seven days with a free Apple ID ran out. Sign it again; Companion does this for you while it runs.

A short checklist for a new personal app

Putting one of your own apps on a phone is the same short routine every time. Once you have done it on a device, most of it never comes up again:

1. Build the app in Borel and try it in the browser.
2. Install it with Borel Companion and your Apple ID.
3. Turn on Developer Mode, once per device.
4. Trust your Apple ID under VPN & Device Management, once per device.
5. Keep Companion running on your computer so the app is renewed before its seven days run out.

My app opens on my iPhone now. Please check the whole app for anything that only works in the simulator: features that need the camera, permission messages that are missing or unclear, and anything that should be saved but is lost when I close the app. List what you find, then fix it one item at a time.

Common mistakes

• Looking under Privacy & Security for the Trust button. Trust is under General, VPN & Device Management. Developer Mode is the one under Privacy & Security.
• Deleting and reinstalling the app to make the message go away. It comes back until you trust the developer.
• Trusting a developer you do not know. Only do it for your own apps or ones from someone you trust.
• Mixing up trust and expiry. A week-old app that stops opening needs renewing, not trusting.
• Forgetting Borel's own iPhone app counts. If you use it, it is one of the three apps a free Apple ID holds.

When you might prefer TestFlight instead

Trusting your own Apple ID is the right route for apps that are just for you. When other people need the app, it is easier for them to install it from TestFlight, Apple's beta app: they tap an invitation, install, and never see VPN & Device Management or Developer Mode. TestFlight needs the app uploaded to App Store Connect, which with Borel happens from your browser on Pro, and Apple's Developer Program membership.

A sensible pattern is both: Companion for your own phone while you build, because each change arrives in minutes, and TestFlight once a few friends should try it. Neither needs a Mac.

What your iPhone checks, and what it does not

Trusting a developer tells iOS that apps signed by that Apple ID may open on this phone. It does not give those apps any extra access: each one still lives in its own sandbox, still asks before it uses the camera, your photos, your location or your contacts, and can be deleted like any other app. If you change your mind, delete the apps from that developer, and the trust goes with them.

The bottom line

"Untrusted Developer" is iOS asking a one-time question about an app you installed yourself. Answer it in Settings, General, VPN & Device Management, and make sure Developer Mode is on. For apps you build in Borel, the developer you are trusting is your own Apple ID.

Ready to put your own app on your phone? Start with how to install your own app without the App Store review, or build one in Borel and try it in your browser while you build.

That message scares a lot of people away from their own apps, and it should not. If you get stuck on it with a Borel app, write to me and I will help you through it.

– Sigsten

Make your iPhone app in Borel

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