BCD File

What are BCD files and how to open them

Are you having problems opening a BCD 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 BCD files.

What is a BCD file?

A .BCD file is a Windows NT Registry Hive file.

Windows NT Registry Hive files store structured system data that Windows needs during boot. One special hive called the Boot Configuration Data (BCD) file holds startup options so that the boot manager knows how to load and configure Windows. It replaces the older boot.ini system starting in Windows Vista. The system reads this hive very early in the startup process.

The BCD hive is created and maintained by Windows components such as Boot Manager and uses registry APIs. It is stored on disk in a protected location: on BIOS-based systems under \Boot\BCD on the boot partition, and on UEFI systems under \EFI\Microsoft\Boot\BCD in the EFI system partition. When Windows is running, it appears under the registry key HKEY_LOCAL_MACHINE\BCD00000000. To modify its contents, Microsoft provides the BCDEdit tool rather than regular registry editors because of its special use and role during boot.

Internally this hive follows the Windows NT Registry File (REGF) format, sharing its major and minor versioning, header structure, hive bin layout, and fields like primary and secondary sequence numbers. The file begins with the ASCII signature "regf". It includes space for metadata such as major/minor version, root cell offset, total size of hive bins, and GUID fields. Specific identifiers like "rmtm" (GUID signature) are present in newer versions.

How to open BCD files

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

While we have not verified the apps ourselves yet, our users have suggested ten different BCD openers which you will find listed below.

Last updated: August 23, 2026

Various apps that use files with this extension

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

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