DFU File

What are DFU files and how to open them

Are you having problems opening a DFU file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your DFU files.

What is a DFU file?

DFU files have multiple uses, and Device Firmware Upgrade format is one of them. Read more about the other uses further down the page.

Device Firmware Upgrade format

.DFU files are the file formats used in upgrading the firmware of devices particularly through the Universal Serial Bus (USB). A firmware is a program that contains information that instructs a specific machine what to do. Firmware upgrades happen when a machine's firmware is upgraded with newer codes or instructions in order for it to function more efficiently.

Firmware upgrades are done using the USB port of a specific device, in which the .DFU files are then specifically read by the machine, signaling it to read its contents with or without the intervention of users.

How to open DFU files

Important: Different programs may use files with the DFU file extension for different purposes, so unless you are sure which format your DFU file is, you may need to try a few different programs.

While we have not verified the app ourselves yet, our users have suggested a single DFU opener which you will find listed below.

Last updated: October 27, 2026

All known file formats using extension .DFU

While Device Firmware Upgrade format is a popular type of DFU-file, we know of 3 different uses of the .DFU file extension. Different software may use files with the same extension for different types of data.

DfuSe device firmware

DfuSe device firmware files store firmware images used with STMicroelectronics' DfuSe protocol, an extension of the USB DFU standard. These files package one or more firmware "images" (or targets), each composed of memory address/value blocks, along with metadata such as device and vendor IDs, firmware version, and layout details. The format is used when upgrading STM32 microcontrollers via USB using DfuSe-compatible tools and bootloaders.

Files are produced by converting binary, Intel HEX, or S-Record-format firmware into the DfuSe container format (for example using ST's DFU File Manager or dfu-util's packing tools). They are consumed by DFU host utilities (such as dfu-util) or ST firmware-upgrade tools, which parse the prefix, select the appropriate image within based on device's alternate setting, send erase and write commands as guided by each image element's address and size, and then validate using a CRC in the suffix.

Each file begins with a DFU prefix header: a fixed signature "DfuSe" at offset 0, followed by a version byte, the total file size, and the number of target images. After that come the image sections: each target has a "Target" prefix including an alternate setting byte, optional name, total size and number of elements; each element includes an address and data size, followed by the raw data to be written. The file ends with a suffix that holds vendor ID, product ID, device version, a fixed DFU version, a signature ("UFD" bytes), and a CRC-32 over the preceding content.

Byte-signatures used to identify this format include the ASCII string "DfuSe" at offset zero, and the ASCII string "Target" (often starting at offset 9) in each target header prefix.

HackRF Firmware

HackRF Firmware is used to hold executable code that runs on HackRF devices when updating or recovering firmware. It is created during the build process of firmware for HackRF-One, HackRF-Pro, Jawbreaker, or rad1o boards by Great Scott Gadgets, and it is used when the device is placed into DFU (Device Firmware Update) mode over USB. The firmware in this format is not stored permanently unless written to SPI flash; instead the format is used to load firmware temporarily into RAM for recovery or testing.

The firmware image builder (part of the HackRF source code) produces this format alongside binary (.bin) images. During normal operation, HackRF boots firmware from SPI flash memory, loading the .bin image. If that image is damaged or missing, HackRF can boot via its ROM bootloader into DFU mode and use the DFU firmware file to accept the code via USB and execute it from RAM. After that, a binary image may be written into flash if permanent operation is desired.

Files in this format begin with specific byte signatures to help HackRF or flashing tools recognize them. At offset zero there is a 16-bit value 0xDAFF. At offset 1040, ASCII text "HACKRFFW" appears.

Various apps that use files with this extension

These apps are known to open certain types of DFU files. Remember, different programs may use DFU files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about DFU file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.