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ASCII85 (.b85)

.b85 file signature | application/octet-stream

ASCII85(aka BASE85) encoded file, sometimes used with PostScript and PDF.Trailer:7E 3E 0A(~>.)

Safe

Magic Bytes

Offset 0
3C 7E 36 3C 5C 25 5F 30 67 53 71 68 3B

Sources: Gary Kessler

Extension

.b85

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .b85 files in Python

Python 
def is_b85(file_path: str) -> bool:
    """Check if file is a valid B85 by magic bytes."""
    signature = bytes([0x3C, 0x7E, 0x36, 0x3C, 0x5C, 0x25, 0x5F, 0x30, 0x67, 0x53, 0x71, 0x68, 0x3B])
    with open(file_path, "rb") as f:
        return f.read(13) == signature

How to validate .b85 files in Node.js

Node.js 
function isB85(buffer: Buffer): boolean {
  const signature = Buffer.from([0x3C, 0x7E, 0x36, 0x3C, 0x5C, 0x25, 0x5F, 0x30, 0x67, 0x53, 0x71, 0x68, 0x3B]);
  return buffer.subarray(0, 13).equals(signature);
}

How to validate .b85 files in Go

Go 
func IsB85(data []byte) bool {
    signature := []byte{0x3C, 0x7E, 0x36, 0x3C, 0x5C, 0x25, 0x5F, 0x30, 0x67, 0x53, 0x71, 0x68, 0x3B}
    if len(data) < 13 {
        return false
    }
    return bytes.Equal(data[:13], signature)
}

API Endpoint

GET /api/v1/b85
curl https://filesignature.org/api/v1/b85

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .b85 file?

A .b85 file is a ASCII85 file. ASCII85(aka BASE85) encoded file, sometimes used with PostScript and PDF.Trailer:7E 3E 0A(~>.)

What are the magic bytes for .b85 files?

The magic bytes for ASCII85 files are 3C 7E 36 3C 5C 25 5F 30 67 53 71 68 3B at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .b85 file?

To validate a .b85 file, read the first bytes of the file and compare them against the known magic bytes (3C 7E 36 3C 5C 25 5F 30 67 53 71 68 3B) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .b85 files?

There is no officially registered MIME type for .b85 files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .b85 files?

ASCII85 (.b85) 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.