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123 (.123)

.123 file signature | application/vnd.lotus-1-2-3;version=97+9.x

Safe

Magic Bytes

Offset 0
00 00 1A 00 03 10 04 00

Sources: Apache Tika

Extension

.123

MIME Type

application/vnd.lotus-1-2-3;version=97+9.x

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .123 files in Python

Python 
def is_123(file_path: str) -> bool:
    """Check if file is a valid 123 by magic bytes."""
    signature = bytes([0x00, 0x00, 0x1A, 0x00, 0x03, 0x10, 0x04, 0x00])
    with open(file_path, "rb") as f:
        return f.read(8) == signature

How to validate .123 files in Node.js

Node.js 
function is123(buffer: Buffer): boolean {
  const signature = Buffer.from([0x00, 0x00, 0x1A, 0x00, 0x03, 0x10, 0x04, 0x00]);
  return buffer.subarray(0, 8).equals(signature);
}

How to validate .123 files in Go

Go 
func Is123(data []byte) bool {
    signature := []byte{0x00, 0x00, 0x1A, 0x00, 0x03, 0x10, 0x04, 0x00}
    if len(data) < 8 {
        return false
    }
    return bytes.Equal(data[:8], signature)
}

API Endpoint

GET /api/v1/123
curl https://filesignature.org/api/v1/123

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .123 file?

A .123 file is a 123 file.

What are the magic bytes for .123 files?

The magic bytes for 123 files are 00 00 1A 00 03 10 04 00 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .123 file?

To validate a .123 file, read the first bytes of the file and compare them against the known magic bytes (00 00 1A 00 03 10 04 00) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .123 files?

The primary MIME type for .123 files is application/vnd.lotus-1-2-3;version=97+9.x.

Is it safe to open .123 files?

123 (.123) 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.