BAC (.bac)

.bac file signature | application/octet-stream

BAC is a backup archive format associated with the AmiBack utility for Amiga systems, originally created by its software developers to store disk images and file backups. It was used for preserving application data, system files, and complete volumes on classic Amiga computers, and can appear in older archival workflows or emulator collections. The format is now largely legacy, but BAC files are generally safe to inspect when handled by compatible archival tools.

Safe

Magic Bytes

Offset 0


              42 41 43 4B 4D 49 4B 45

Sources: Wikipedia

All Known Signatures

2 signature variants are documented for .bac files across multiple sources.

Hex Signature	Offset	Sources
42 41 43 4B 4D 49 4B 45	0	Wikipedia
44 49 53 4B	0	Wikipedia

Extension

.bac

MIME Type

application/octet-stream

Byte Offset

Risk Level

Safe

Validation Code

How to validate .bac files in Python

Python

def is_bac(file_path: str) -> bool:
    """Check if file is a valid BAC by magic bytes."""
    signature = bytes([0x42, 0x41, 0x43, 0x4B, 0x4D, 0x49, 0x4B, 0x45])
    with open(file_path, "rb") as f:
        return f.read(8) == signature

How to validate .bac files in Node.js

Node.js

function isBAC(buffer: Buffer): boolean {
  const signature = Buffer.from([0x42, 0x41, 0x43, 0x4B, 0x4D, 0x49, 0x4B, 0x45]);
  return buffer.subarray(0, 8).equals(signature);
}

How to validate .bac files in Go

func IsBAC(data []byte) bool {
    signature := []byte{0x42, 0x41, 0x43, 0x4B, 0x4D, 0x49, 0x4B, 0x45}
    if len(data) < 8 {
        return false
    }
    return bytes.Equal(data[:8], signature)
}

API Endpoint

GET /api/v1/bac


              curl https://filesignature.org/api/v1/bac

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .bac file?

A .bac file is identified by the magic bytes 42 41 43 4B 4D 49 4B 45 at byte offset 0. BAC is a backup archive format associated with the AmiBack utility for Amiga systems, originally created by its software developers to store disk images and file backups. It was used for preserving application data, system files, and complete volumes on classic Amiga computers, and can appear in older archival workflows or emulator collections. The format is now largely legacy, but BAC files are generally safe to inspect when handled by compatible archival tools.

What are the magic bytes for .bac files?

The magic bytes for BAC files are 42 41 43 4B 4D 49 4B 45 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .bac file?

To validate a .bac file, read the first bytes of the file and compare them against the known magic bytes (42 41 43 4B 4D 49 4B 45) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .bac files?

There is no officially registered MIME type for .bac files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .bac files?

BAC (.bac) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.