What is the IPSW file format?
An IPSW file is an archive compressed as a ZIP that contains the complete firmware bundle used to restore or update an Apple device. The name stands for iPhone Software, though the same format is used for iPad, iPod touch, Apple TV and HomePod firmware.
IPSW archives contain multiple AES-encrypted DMG filesystem images - the root OS, update ramdisk and restore ramdisk - along with per-component firmware payloads (.im4p), a device-tree file and a BuildManifest.plist that lists every supported board and image hash. Renaming .ipsw to .zip lets any archive tool inspect the contents, though the inner images remain encrypted.
Restoring a device from an IPSW requires Apple's signing server (TSS) to approve the operation. Once Apple closes a firmware's signing window, that version can no longer be installed - making true downgrades impossible on modern devices. On macOS Catalina and later, restores are handled by Finder (or Apple Configurator); on Windows the recommended tool is the Apple Devices app (2024), with iTunes as a legacy fallback.
IPSW files range from roughly 3 GB to 12 GB depending on the device and iOS version. Because Apple's servers provide current firmware directly, locally cached IPSW files can generally be deleted and re-downloaded when needed.
Security & safety
RISK: MEDIUMThe .ipsw file itself is just firmware data and not executable on your PC, but RESTORING one is consequential: choosing 'Restore' ERASES the device, and applying firmware can brick a device if interrupted or if the wrong/modified image is used. Only use IPSWs that match your exact device model and that Apple is still signing - a custom/unsigned or tampered IPSW will be rejected (or, in jailbreak workflows, can leave a device unbootable). Download IPSWs only from Apple or well-known mirrors (e.g. ipsw.me); avoid random 'iOS firmware' sites that bundle adware or altered images. Restoring also typically removes a jailbreak and updates baseband, which can be irreversible.
Format details
in a nutshellPrograms that open IPSW files
Windows3 apps
7-Zip
Open-source Right-click > 7-Zip > Open archive to inspect the IPSW's contents (it's a ZIP). Does NOT restore - view/extract only. 
Apple Devices app
Free Apple's recommended Windows tool (since 2024): connect the device, Shift-click 'Restore' and select the .ipsw. Replaces iTunes for device management.
iTunes (legacy Windows)
Free On older/unsupported Windows setups, connect the device and Shift-click 'Restore iPhone', then choose the .ipsw. Being superseded by the Apple Devices app. 
macOS2 apps
Finder (macOS Catalina and later)
Built-in Connect the device, select it in the Finder sidebar, then Option-click 'Restore iPhone/iPad' and choose the .ipsw. (iTunes was removed from macOS in 2019.)
Apple Configurator
Free Free Apple tool for mass/manual device management; can apply an .ipsw to a connected device (useful for DFU restores). Technical details
deep spec| Container format | ZIP archive (renamed; standard PKZIP structure with PK magic bytes) |
| Typical file size | 3 GB - 12 GB (varies by device model and iOS/iPadOS version) |
| Compression | DEFLATE per ZIP entry; inner .dmg images carry their own compression |
| Inner image encryption | AES-encrypted .dmg filesystem images (root OS, update ramdisk, restore ramdisk) |
| Firmware payload format | IMG4/IM4P per-component signed payloads (.im4p files) for kernel, iBoot, etc. |
| Baseband firmware | Included as .bbfw (baseband firmware) for cellular-capable devices |
| Manifest file | BuildManifest.plist at ZIP root - lists supported board IDs, build string and per-image hashes |
| Apple signing requirement | Restore must be TSS-approved by Apple's servers; unsigned or out-of-window IPSWs are rejected |
| Downgrade limitation | Once Apple closes a firmware's signing window, that version cannot be installed on any device |
| Supported devices | iPhone, iPad, iPod touch, Apple TV (tvOS), HomePod (audioOS) |
| Restore tool (macOS) | Finder (macOS Catalina+) or Apple Configurator |
| Restore tool (Windows) | Apple Devices app (2024 release); iTunes as legacy fallback |
| Released | 2007 (with the original iPhone / iPhone OS 1.0) |
| Latest version | Current per iOS/iPadOS release (e.g. iOS 18-era IPSWs); bundle layout governed by Apple's BuildManifest |
| Specification | ipsw.me |
IPSW conversions
Community Q&A
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