What is the FAP file format?
A .fap file is a Flipper Application Package, an application built for the Flipper Zero multi-tool made by Flipper Devices. Under the hood it is an .elf object file compiled for the STM32WB55's ARM Cortex-M4 core, with Flipper-specific metadata, an icon, and resources bundled into extra sections.
Because the Flipper's microcontroller cannot run code straight from the SD card, the firmware's App Loader copies a .fap into RAM, checks that its API version is compatible, applies relocations, and resolves the firmware functions it calls before running it. Each package records the firmware API version it was built against, so an app keeps working across firmware builds as long as the major version matches. Developers create FAPs with the Flipper Build Tool (FBT or the lighter ufbt), driven by an application.fam manifest that marks the app as external.
Security & safety
RISK: MEDIUMA .fap is native ARM code that runs on the Flipper Zero, so a malicious or buggy app could misbehave on the device, though it runs in the Flipper's constrained environment and cannot infect a desktop PC by sitting on it. The main caution is that FAPs can drive the Flipper's radios and GPIO in ways that may be illegal or harmful if misused. Install FAPs from the official catalog or trusted repositories, and be aware community apps are not reviewed as strictly as official ones.
Format details
in a nutshellFULL NAMEFlipper Application Packageaka Flipper App Package, FAP
DEVELOPERFlipper Devicessince 2022
CATEGORYExecutable Files
MIME TYPEapplication/octet-stream
TYPEBinary (ELF-based relocatable executable with embedded metadata and resources)
This extension is also used by…
- FileMaker (older ACT! / generic) - The .fap extension has occasionally appeared as an application or project file in older niche software, unrelated to Flipper Zero.
- Generic 'application package' data - Some legacy tools used .fap as an ad hoc application data file; these predate and are unrelated to the Flipper Application Package.
MAGIC BYTES · FILE SIGNATURE
OFFSET
00010203
HEX
7F454C46
ASCII
·ELF
A FAP begins with the standard ELF magic (0x7F 'E' 'L' 'F') because it is an ELF object file. It has no unique .fap signature; the Flipper-specific metadata (fap_version, api version, icon, name) is embedded in ELF sections, so the file is identified by its .fap extension and ELF contents rather than a distinct header.
Programs that open FAP files
Windows3 apps
qFlipper
Free Connect the Flipper Zero over USB, open Applications, choose Install Application, and select the .fap to write it to the device.
Flipper Lab (lab.flipper.net)
Free Open the site in a browser with the Flipper connected over USB and install a .fap straight from the catalog or a local file.
Flipper Build Tool (FBT / ufbt)
Open-source Build, launch, or debug a .fap from source using ufbt or fbt fap_{APPID} targets. 
macOS3 apps
qFlipper
Free Connect the Flipper over USB, open Applications, choose Install Application, and pick the .fap to install it.
Flipper Lab (lab.flipper.net)
Free Install a .fap from the web catalog while the Flipper is plugged in over USB.
Flipper Build Tool (FBT / ufbt)
Open-source Compile and deploy a .fap from app source using the ufbt toolchain. 
Linux3 apps
qFlipper
Free Attach the Flipper over USB, open Applications, choose Install Application, and select the .fap to flash it to the device.
Flipper Lab (lab.flipper.net)
Free Use the browser catalog to install a .fap onto a connected Flipper Zero.
Flipper Build Tool (FBT / ufbt)
Open-source Run ufbt launch or fbt fap_{APPID} to build a .fap and load it onto the device. 
Android1 app
Flipper Mobile App
Free Pair with the Flipper over Bluetooth, open the Apps section in the Hub tab, and install a .fap from the catalog.
iOS1 app
Flipper Mobile App
Free Connect to the Flipper over Bluetooth, open Apps in the Hub tab, and tap Install on the .fap you want. Technical details
deep spec| Encoding | Binary ELF object file |
| Byte order | Little-endian |
| Container | ELF (Executable and Linkable Format) |
| Elf Machine | ARM (Cortex-M4F / Thumb), targeting the STM32WB55 MCU on Flipper Zero |
| Code Model | Relocatable / position-independent; the App Loader processes relocations and resolves imported firmware symbols at load time |
| Symbol Resolution | Imported functions are resolved against the firmware symbol table generated from api_symbols.csv |
| Embedded Metadata | App name, icon, category, stack size, fap_version and required firmware API version stored in dedicated ELF sections |
| Resources | Static and animated images can be bundled as private assets via the fap_icon_assets manifest field |
| Build Tool | Flipper Build Tool (FBT / ufbt), configured through an application.fam manifest with apptype FlipperAppType.EXTERNAL |
| Loading | Cannot execute in place from SD card; the App Loader copies the FAP into RAM, verifies compatibility, applies relocations, then runs it |
| Typical size | A few kilobytes to a few hundred kilobytes |
| Integrity | App Loader verifies API-version compatibility before running; no separate CRC/hash in the file itself |
| Platforms | Flipper Zero firmware (FreeRTOS-based) |
| Structure | Standard ELF layout (ELF header, program/section headers, .text/.data/.rodata, relocation and symbol tables) plus custom sections carrying Flipper app manifest data and icon assets. |
| Notes | FAPs are not tied to one firmware build; compatibility is decided by the required API version embedded in the file. Distributed through the official Flipper Apps catalog (lab.flipper.net), the Flipper mobile app, and community repositories. |
| Released | 2022 |
| Latest version | Tied to firmware API version (major.minor) |
| Specification | developer.flipper.net |
FAP conversions
Possible
Community Q&A
asked by usersNo questions yet - be the first to ask about FAP files.
Frequently asked questions
How do I open a .fap file?
You install it onto a Flipper Zero rather than opening it on a computer. Use qFlipper or Flipper Lab over USB, the Flipper mobile app over Bluetooth, or copy the
.fap to the SD card's apps folder and launch it from Apps > External on the device.Can I open a .fap file on my PC?
Not to run it. A PC cannot execute Flipper ARM code. You can inspect a
.fap as an ELF binary with tools like readelf or Ghidra, but it only works on a Flipper Zero.Where do FAP files go on the SD card?
They live in category subfolders under the
apps directory on the Flipper's microSD card. The category comes from the app's manifest, and the app then shows up under Apps on the device.Why won't my FAP file load on the Flipper?
Most load failures come from an API version mismatch. The FAP was built for a different firmware API version than your Flipper is running. Update the app or the firmware so the major API versions match.
How do I create a .fap file?
Write the app in C, add an
application.fam manifest with apptype FlipperAppType.EXTERNAL, and build it with the Flipper Build Tool (FBT) or the standalone ufbt.Are FAP files safe to install?
FAPs from the official catalog are the safest. Community FAPs are native code with access to the Flipper's hardware, so only install from sources you trust and follow local laws when using radio or access features.
References
1Flipper Developer Docs - FAP (Flipper App Package)developer.flipper.net
2Flipper firmware documentation - AppsOnSDCard.mdgithub.com
