Turn on Developer Mode on an iPhone.

What Developer Mode actually is

Every iPhone has always carried a set of services meant for the people writing software for it: installing a build from a computer, attaching a debugger, capturing performance traces, simulating a location. Until iOS 16 those services were simply there, on every phone in the world, waiting for a computer the phone trusted to ask. Almost nobody used them, and a facility that is present on a billion devices and wanted by a few hundred thousand is a poor trade.

Developer Mode is the switch Apple added in iOS 16 to close that gap. With it off, the developer services do not answer at all, whatever a connected computer asks. With it on, they answer as they always did. It is a per-device opt-in, and it is the phone's owner who does the opting: enabling it requires the phone in your hand, the screen unlocked and the passcode typed in.

Once it is on it stays on. It survives restarts, updates and having the cable pulled out, and it does not expire. You turn it on once for a phone you develop against or test with, and then forget about it.

Turning it on

1. Plug the phone into the computer first

   This is out of order compared with every other guide, and it is deliberate. On a phone that has never met developer tooling, the menu item you are about to look for does not exist. Connect the cable, unlock the phone, tap Trust if you are asked, and let the desktop tool you intend to use try to talk to it once.

2. Open Settings → Privacy & Security

   Scroll to the bottom of that screen, past Location Services and the tracking controls, to the security headings. Developer Mode sits among them, near Lockdown Mode.

3. Switch Developer Mode on

   The phone answers with a Restart Required alert explaining that Developer Mode reduces the device's security. Tap Restart. The phone reboots straight away, so finish anything you were in the middle of first.

4. Confirm on the way back up

   After the reboot, unlock the phone and a prompt asks whether to turn Developer Mode on. Tap Turn On and enter your passcode. Miss it and nothing is broken. The toggle is simply still off, and you can start again from Settings.

5. Check it took

   Go back to Settings → Privacy & Security → Developer Mode and confirm the switch is green. On the computer, reconnect and try again; a tool that was refusing on grounds of Developer Mode should now proceed.

When Developer Mode is not in Settings

This is the failure worth reading the page for. Apple hides the menu item until the phone has received a request from developer tooling over the cable, so a phone that has only ever been charged, synced or backed up shows no Developer Mode row at all: not greyed out, not disabled, simply absent. People then search for it, find screenshots that show it, and conclude their phone is broken or the setting has moved.

If it still is not there after that, work down this list.

1. Check the iOS version. Settings → General → About. Below 16 there is no Developer Mode, and nothing you do will produce one.
2. Check Trust actually happened. An untrusted phone accepts power and refuses everything else, so no request ever reaches it. Unplug, replug, unlock, and watch for the prompt. If the prompt never appears, the pairing record on the computer may be stale, and the detection guide covers resetting it.
3. Check the cable. A charge-only cable carries power and no data. The phone charges, the computer sees nothing, and no developer request is ever made.
4. Check the phone is supervised or managed. Work and school devices under mobile device management can have the whole thing suppressed by policy, in which case the answer is your IT administrator rather than another cable.

iOS 15 and older

There is nothing to do. Developer Mode arrived in iOS 16, and before it the developer services were reachable as soon as the phone trusted the computer. If you are on iOS 15 or earlier, tap Trust and carry on; a guide telling you to enable Developer Mode on such a device is describing a switch that does not exist. The same applies to iPadOS: 16 and newer have it, 15 and older do not.

Turning it off again

The same toggle, switched the other way. It is worth knowing what that costs before you do it: turning Developer Mode off discards data that developer tooling put on the device, so development builds installed from a computer and whatever they had stored locally go with it. An app you installed from the App Store is untouched, and so are your photos, messages and settings. This only reaches things that were put there by a developer workflow in the first place.

Turning it back on later is the same procedure as the first time, restart included. Most people who use it regularly leave it on, because there is no running cost to having done so.

What Developer Mode is not

Two claims get made about it constantly, and both are wrong.

• It is not a jailbreak. Nothing is unlocked, no protection is removed and nothing gains root. Code signing, sandboxing and every other iOS security boundary behave exactly as before. Developer Mode decides whether a specific set of Apple's own services will answer, and that is the whole of its effect.
• It is not a hole someone can walk through. Reaching the services it permits needs physical possession of the phone, an unlocked screen, the passcode and an explicit Trust for that particular computer. The switch narrows Apple's exposure rather than widening yours, which is why it exists.

The alert Apple shows when you enable it does say Developer Mode reduces the device's security, and that is fair: a phone that will answer developer requests has more surface than one that will not. It is a change of degree on a device you are holding, not a change of kind.

Questions

Where is Developer Mode on iPhone?

Settings → Privacy & Security → Developer Mode, near the bottom of that screen under the security headings. It exists only on iOS 16 and newer, and it only appears once the phone has been connected to a computer running developer tooling at least once.

Why is Developer Mode not showing in Settings?

Because the phone has never been asked for anything by developer tooling. Apple hides the menu item until a connected computer requests a developer service, so on a phone that has only ever been charged and backed up there is nothing to find. Plug it into the computer you intend to use, let the desktop tool try to connect, then look in Settings again. The other reason is iOS 15 or older, which has no Developer Mode at all.

Is Developer Mode safe?

Yes. It is not a jailbreak, it does not grant anything root access and it removes none of iOS's protections. It is an opt-in switch that decides whether developer services will answer at all, and reaching those services still needs physical possession of the phone, an unlocked screen, the passcode and an explicit Trust. Apple added it in iOS 16 to shrink the attack surface on phones whose owners never asked for developer features.

Does Developer Mode drain the battery?

No. Developer Mode gates services; it does not run anything. Nothing polls, nothing sits in the background and nothing is scheduled because the switch is on. The services it permits only do work when a connected computer asks them to, and when nothing is plugged in nothing is asking.

Do I need Developer Mode on iOS 15?

No, and you could not turn it on if you wanted to. Developer Mode arrived in iOS 16. On iOS 15 and older there is no toggle and nothing to do: the developer services are reachable once the phone trusts the computer, so location simulation and similar tools work as soon as you have tapped Trust.