Lotus 1-2-3 spreadsheet (.wk3)
.wk3 file signature | application/vnd.lotus-1-2-3;version=3
Lotus 1-2-3 spreadsheet (WK3) is a legacy spreadsheet file format created by Lotus Development Corporation and later supported by IBM through Lotus products. It was used for worksheets, calculations, charts, and business data exchange in Lotus 1-2-3 and compatible spreadsheet applications. The format is obsolete and generally safe to open, though files from untrusted sources should still be handled with standard caution.
Magic Bytes
Offset 0
00 00 1A 00 00 10 04 00 00 00 00 00
Sources: Wikipedia, Gary Kessler
All Known Signatures
2 signature variants are documented for .wk3 files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 00 00 1A 00 00 10 04 00 00 00 00 00 | 0 | Wikipedia, Gary Kessler |
| 00 00 1A 00 00 10 04 00 | 0 | Apache Tika |
Extension
.wk3
MIME Type
application/vnd.lotus-1-2-3;version=3
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .wk3 files in Python
def is_wk3(file_path: str) -> bool:
"""Check if file is a valid WK3 by magic bytes."""
signature = bytes([0x00, 0x00, 0x1A, 0x00, 0x00, 0x10, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00])
with open(file_path, "rb") as f:
return f.read(12) == signatureHow to validate .wk3 files in Node.js
function isWK3(buffer: Buffer): boolean {
const signature = Buffer.from([0x00, 0x00, 0x1A, 0x00, 0x00, 0x10, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00]);
return buffer.subarray(0, 12).equals(signature);
}How to validate .wk3 files in Go
func IsWK3(data []byte) bool {
signature := []byte{0x00, 0x00, 0x1A, 0x00, 0x00, 0x10, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00}
if len(data) < 12 {
return false
}
return bytes.Equal(data[:12], signature)
}API Endpoint
/api/v1/wk3
curl https://filesignature.org/api/v1/wk3
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .wk3 file?
A .wk3 file is a Lotus 1-2-3 spreadsheet file. Lotus 1-2-3 spreadsheet (WK3) is a legacy spreadsheet file format created by Lotus Development Corporation and later supported by IBM through Lotus products. It was used for worksheets, calculations, charts, and business data exchange in Lotus 1-2-3 and compatible spreadsheet applications. The format is obsolete and generally safe to open, though files from untrusted sources should still be handled with standard caution.
What are the magic bytes for .wk3 files?
The magic bytes for Lotus 1-2-3 spreadsheet files are 00 00 1A 00 00 10 04 00 00 00 00 00 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .wk3 file?
To validate a .wk3 file, read the first bytes of the file and compare them against the known magic bytes (00 00 1A 00 00 10 04 00 00 00 00 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 .wk3 files?
The primary MIME type for .wk3 files is application/vnd.lotus-1-2-3;version=3.
Is it safe to open .wk3 files?
Lotus 1-2-3 spreadsheet (.wk3) 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.