AltStore vs Scarlet iOS vs Sideloadly: Ultimate Guide

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AltStore, Scarlet iOS, and Sideloadly are the three most widely used sideloading tools for iPhone in 2026. Each takes a different approach to the same fundamental challenge: installing IPA files on iOS without Apple’s approval. This guide goes deep on every meaningful difference to help you choose the right tool — or combination of tools — for your needs.

Quick Summary for Busy Readers

  • Scarlet iOS: On-device, no computer, largest app library, easiest to use. Best for most users.
  • AltStore: Computer required, uses your Apple ID, most privacy-preserving, reliable 7-day re-signing. Best for developers and privacy-focused users.
  • Sideloadly: Computer required, best Apple ID authentication, supports both free and paid developer accounts. Best computer-based tool for flexibility.

How Each Tool Works

Scarlet iOS

Scarlet iOS is an on-device solution. It uses enterprise/developer certificates obtained from Scarlet’s certificate rotation infrastructure to sign IPA files directly on your device. You install Scarlet through Safari on your iPhone, then use its built-in interface to browse repos, download, and install apps — all without ever connecting to a computer. Certificate management is largely automated.

AltStore

AltStore requires AltServer — a companion app running on a Mac or PC. AltServer handles the signing process using your personal Apple ID developer certificate. Your iPhone communicates with AltServer over Wi-Fi (or USB) to install and re-sign apps. Because it uses your personal Apple ID certificate, apps are uniquely signed for your account. The 7-day expiry applies unless you have a paid Apple Developer account ($99/year), in which case apps are valid for a year.

Sideloadly

Sideloadly is a Mac/Windows desktop app that functions as an advanced IPA signer and installer. You provide your Apple ID credentials, select an IPA file, and Sideloadly connects your iPhone via USB or Wi-Fi to sign and install the app. It supports both free Apple ID accounts (7-day certificates) and paid developer accounts (1-year certificates). Sideloadly has the most robust Apple ID authentication handling of any computer-based tool.

Installation Process Compared

Scarlet iOS Installation

  1. Open Safari on iPhone, go to scarletios.com
  2. Tap Download, install profile, trust certificate
  3. Total time: 2-3 minutes. No computer needed.

AltStore Installation

  1. Download AltServer on your Mac or PC
  2. Install Apple Music or iTunes if not present
  3. Connect iPhone via USB, run AltServer installer
  4. Enter Apple ID credentials in AltServer
  5. AltStore installs on iPhone
  6. Total time: 10-20 minutes. Computer required.

Sideloadly Installation

  1. Download Sideloadly desktop app from official site
  2. Install Apple Mobile Device Support (Windows) or iTunes
  3. Connect iPhone via USB on first use
  4. Enter Apple ID and generate app-specific password
  5. Drag IPA file to Sideloadly and click Start
  6. Total time: 15-30 minutes initial setup. Computer required.

App Library Comparison

This is where the tools diverge most significantly:

  • Scarlet iOS: Built-in repo system with thousands of apps. Tweaked apps, modded games, emulators, utilities, paid app IPAs. Browse and install from the device with search and categories.
  • AltStore: Small official library (Delta, Clip, and a handful of others). Supports adding third-party AltStore sources. Much smaller ecosystem than Scarlet.
  • Sideloadly: No built-in app library. You must provide your own IPA files. Pure signing tool with no discovery features.

Re-signing and Certificate Management

Apps signed with personal Apple ID certificates (AltStore and Sideloadly free tier) expire every 7 days. Apps signed with Scarlet’s certificates expire when Apple revokes the certificate — which may be weeks or months.

  • Scarlet iOS: Automatic re-signing when certificates are revoked. Manual re-sign button available. Revocations happen but are quickly addressed.
  • AltStore: Automatic re-signing every 7 days when iPhone is on same Wi-Fi as AltServer. Requires computer to be on and connected to the same network.
  • Sideloadly: Manual re-signing required. You must open Sideloadly on your computer and re-sign before the 7-day expiry. More maintenance overhead.

Privacy Comparison

  • Scarlet iOS: Does not require your Apple ID. Your Apple account is not involved at any point. Certificate infrastructure is Scarlet’s, not yours.
  • AltStore: Uses your Apple ID. Apple can technically see that your account is signing non-App Store apps, though this is not typically actioned against regular users.
  • Sideloadly: Uses your Apple ID. Same considerations as AltStore.

Cost Comparison

  • Scarlet iOS: Free to use with the standard certificate tier
  • AltStore: Free with personal Apple ID. AltStore PAL (EU) has a small fee for expanded capabilities
  • Sideloadly: Free with personal Apple ID. Paid developer account ($99/year) removes 7-day expiry

Which Tool for Which User?

After comparing every dimension, here are the clearest recommendations:

  • iPhone user wanting tweaked apps, games, and utilities with zero technical complexity: Scarlet iOS
  • Developer wanting to test their own apps on device: AltStore or Sideloadly with paid developer account
  • Privacy-focused user wanting no Apple ID involvement: Scarlet iOS
  • User needing a specific IPA not in any repo: Sideloadly (can install any IPA file you provide)
  • User without access to a computer at all: Scarlet iOS (the only viable option)

Many power users run both Scarlet iOS and AltStore — Scarlet for app discovery and the broad library, AltStore for a few key apps that work better with personal certificate signing. Visit scarletios.com to get started with Scarlet iOS today, and read our Scarlet iOS vs AltStore comparison for even more detail on those two tools.

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