123
application/vnd.lotus-1-2-3;version=97+9.x
Magic Bytes
Offset: 0
00 00 1A 00 03 10 04 00
The 123 file format is a proprietary spreadsheet workbook structure developed by Lotus Software and later managed by IBM. It is primarily used for storing tabular data, mathematical formulas, and graphical charts within version 9.7 and newer releases of the Lotus 1-2-3 productivity suite. Now considered a legacy format following its 2013 discontinuation, it is generally safe to open, though modern users typically require third-party tools like LibreOffice to access archived spreadsheet data.
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) == signatureHow 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);
}
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