On-Device Signing vs Computer Signing: Pros and Cons

ByScarlet iOS Team Updated on

There are two main ways to sign and install IPA files on an iPhone: on the device itself (like Scarlet iOS, ESign, Feather or KSign) or from a computer (like AltStore, SideStore’s first setup and Sideloadly). The real difference is not where the signing happens but whose certificate is used: a shared certificate, your own free Apple ID, or a paid developer account. This guide compares both approaches on the points that matter in daily use and ends with a table to help you choose. For what Apple has changed about signing recently, see iOS app signing in 2026. Updated October 27, 2026.

The Short Version

  • On-device signing with a shared certificate (Scarlet iOS and similar): no computer, a shared certificate instead of your Apple ID, and no 3-app limit, but Apple can revoke the certificate, and then the apps stop opening until a new one is available.
  • Computer signing with your free Apple ID (AltStore, Sideloadly): apps are signed for your device only, but they expire after 7 days, you can have only 3 at a time, and you need a computer.
  • A paid Apple Developer account ($99 a year) removes the 3-app limit and makes apps last up to a year, with either approach.
  • You can combine them: an on-device installer for convenience, and their own Apple ID for the one or two apps that must keep working.

Decision Table

What matters to you On-device, shared certificate Computer, free Apple ID Paid developer account
No computer Yes No (SideStore: only for the first setup) Depends on the tool
Your Apple ID used for signing No (shared certificate) Yes Yes
Number of apps No 3-app limit 3 active apps, 10 App IDs per 7 days No 3-app limit
How long apps last Until the certificate is revoked or expires 7 days, then re-sign Up to 1 year
Revocation risk Yes, affects all users at once Low (signed for your device only) Low for your own account
JIT for emulators No Yes, with extra tools Yes, with extra tools
Device UDID needed No No (the tool handles it) Yes, registered on the account
Cost Free Free $99 a year

If two or three rows matter to you at once, the combined setup at the end of this guide is usually the answer.

What Is On-Device Signing?

On-device signing means the whole process (downloading, signing and installing an IPA) happens on the iPhone. There are two kinds:

  • Shared-certificate installers such as Scarlet iOS sign apps with a distribution certificate the service provides. You do not need an Apple ID or a computer.
  • On-device signers with your own certificate such as KSign or Feather (see Feather vs Scarlet iOS) sign apps on the iPhone with a certificate file you import. How stable that is depends entirely on where the certificate comes from.

What Is Computer Signing?

Computer signing uses a desktop app (AltServer for AltStore, or Sideloadly) to sign the IPA with your Apple ID and install it over USB or Wi-Fi. The certificate belongs to your own Apple ID, so it is not shared with other users. SideStore is a hybrid: it needs a computer once for the setup, then signs and refreshes apps on the iPhone with your Apple ID; see how to install SideStore.

Risks and Limits of On-Device Signing (Shared Certificate)

Certificate revocation

Apple revokes distribution certificates that are used to hand out apps to the public. When that happens, every app signed with the certificate stops opening for every user at the same time. You then wait until the installer has a working certificate and reinstall; see what to do when a certificate is revoked.

You trust the certificate provider

A shared certificate is controlled by someone else. You depend on them keeping it working, and you trust their app source. Our guide to enterprise certificate safety explains what to check.

No JIT

Apps signed with a shared distribution certificate cannot get JIT, so emulators that need it (such as DolphiniOS or Play!) do not run games. For those, see the StikDebug JIT guide.

Advantages of On-Device Signing

  • No computer. Everything happens on the iPhone, which matters if you have no Mac or PC at hand; see installing Scarlet without a computer, or open our Scarlet iOS install page in Safari.
  • Shared certificate instead of your Apple ID. A shared-certificate installer signs with its own certificate, so your account stays out of the signing.
  • No 3-app limit and no 10 App ID limit, because the free Apple ID rules do not apply.
  • Built-in sources. On-device installers can add repositories and also import your own IPA files.

Risks and Limits of Computer Signing (Free Apple ID)

7-day expiry

Apps signed with a free Apple ID stop opening after 7 days unless they are refreshed. AltStore and Sideloadly can refresh automatically, but only while the computer can reach the iPhone over Wi-Fi or USB.

3 apps and 10 App IDs

Apple allows 3 active apps signed with a free Apple ID per device (AltStore and SideStore count themselves) and 10 new App IDs every 7 days. Hitting either limit gives an error; see how to fix the 3-app limit error.

You need a computer

The first install always needs Windows or a Mac. With AltStore and Sideloadly the computer is needed for every refresh, too.

Your Apple ID is used

You sign in with an Apple ID. You can use a second, free Apple ID for sideloading to keep your main account separate.

Advantages of Computer Signing

  • Not shared. The certificate belongs to your Apple ID, so other people’s use cannot get it revoked.
  • Any IPA. You bring the file, so you are not limited to what a source offers. Check unknown files first; see how to scan IPA files for malware.
  • JIT is possible with development-signed apps and a tool such as StikDebug.
  • Advanced options. Sideloadly can change an app’s name, icon or bundle ID, so you can install a second copy of an app.

What a Paid Developer Account Changes

An Apple Developer Program membership ($99 a year) works with both approaches: you can sign from a computer with it, or export its certificate to an on-device signer such as KSign. It removes the 3-app limit and makes apps last up to a year. Each device has to be registered on the account with its UDID; see how to find your iPhone UDID. For the full comparison, read Apple Developer account vs free sideloading.

Be careful with sellers of cheap “developer certificates”: those are often shared between many buyers, which brings back the revocation risk.

Which Should You Choose?

  • You have no computer: an on-device installer such as Scarlet iOS. Accept that a revoke can stop your apps for a while.
  • You need 1 to 3 apps that must always work: your own Apple ID with SideStore, AltStore or Sideloadly.
  • You want emulators that need JIT: SideStore plus StikDebug.
  • You need many apps and maximum stability: a paid developer account.
  • A mix: an on-device installer for most apps and your own Apple ID for the important few. Our free sideloading tools comparison covers each tool.

Scarlet iOS is confirmed on iOS 14 through iOS 26; iOS 27 support is reported by third parties but not officially confirmed.

FAQ

Is on-device signing less safe?

The signing itself is not less safe. The difference is trust: with a shared certificate you trust the service that provides it and the sources you install from. With your own Apple ID, only you control the certificate.

Why do my apps stop after 7 days?

That is the normal expiry of apps signed with a free Apple ID. Refresh them in your tool. A shared-certificate revoke looks different: all apps from the installer stop at the same time.

Can I use both methods on one iPhone?

Yes. Apps from a shared-certificate installer do not count toward the free Apple ID’s 3-app limit.

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