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XLD (.xld)

.xld file signature | application/vnd.ms-excel

XLD is a legacy spreadsheet file format developed by Microsoft for early versions of Excel. It was used to store worksheets, formulas, and tabular data for business, reporting, and data analysis tasks, and may still be encountered in archived office documents. The format is obsolete, and modern spreadsheet applications may open it with limited fidelity; files from untrusted sources should still be handled with standard caution.

Safe

Magic Bytes

Offset 2080
4D 69 63 72 6F 73 6F 66 74 20 45 78 63 65 6C 20 35 2E 30 20 57 6F 72 6B 73 68 65 65 74

Sources: Apache Tika

All Known Signatures

5 signature variants are documented for .xld files across multiple sources.

Hex Signature Offset Sources
4D 69 63 72 6F 73 6F 66 74 20 45 78 63 65 6C 20 35 2E 30 20 57 6F 72 6B 73 68 65 65 74 2080 Apache Tika
46 6F 67 6C 69 6F 20 64 69 20 6C 61 76 6F 72 6F 20 4D 69 63 72 6F 73 6F 66 74 20 45 78 63 65 2080 Apache Tika
42 69 66 66 35 2114 Apache Tika
42 69 66 66 35 2121 Apache Tika
D0 CF 11 E0 A1 B1 1A E1 0 Apache Tika

Extension

.xld

MIME Type

application/vnd.ms-excel

Byte Offset

2080

Risk Level

Safe

Validation Code

How to validate .xld files in Python

Python 
def is_xld(file_path: str) -> bool:
    """Check if file is a valid XLD by magic bytes at offset 2080."""
    signature = bytes([0x4D, 0x69, 0x63, 0x72, 0x6F, 0x73, 0x6F, 0x66, 0x74, 0x20, 0x45, 0x78, 0x63, 0x65, 0x6C, 0x20, 0x35, 0x2E, 0x30, 0x20, 0x57, 0x6F, 0x72, 0x6B, 0x73, 0x68, 0x65, 0x65, 0x74])
    with open(file_path, "rb") as f:
        f.seek(2080)
        return f.read(29) == signature

How to validate .xld files in Node.js

Node.js 
function isXLD(buffer: Buffer): boolean {
  const signature = Buffer.from([0x4D, 0x69, 0x63, 0x72, 0x6F, 0x73, 0x6F, 0x66, 0x74, 0x20, 0x45, 0x78, 0x63, 0x65, 0x6C, 0x20, 0x35, 0x2E, 0x30, 0x20, 0x57, 0x6F, 0x72, 0x6B, 0x73, 0x68, 0x65, 0x65, 0x74]);
  if (buffer.length < 2109) return false;
  return buffer.subarray(2080, 2109).equals(signature);
}

How to validate .xld files in Go

Go 
func IsXLD(data []byte) bool {
    signature := []byte{0x4D, 0x69, 0x63, 0x72, 0x6F, 0x73, 0x6F, 0x66, 0x74, 0x20, 0x45, 0x78, 0x63, 0x65, 0x6C, 0x20, 0x35, 0x2E, 0x30, 0x20, 0x57, 0x6F, 0x72, 0x6B, 0x73, 0x68, 0x65, 0x65, 0x74}
    if len(data) < 2109 {
        return false
    }
    return bytes.Equal(data[2080:2109], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Related Formats

.xlc .xll .xlm .xlt .xlw .xla

Frequently Asked Questions

What is a .xld file?

A .xld file is identified by the magic bytes 4D 69 63 72 6F 73 6F 66 74 20 45 78 63 65 6C 20 35 2E 30 20 57 6F 72 6B 73 68 65 65 74 at byte offset 2080. XLD is a legacy spreadsheet file format developed by Microsoft for early versions of Excel. It was used to store worksheets, formulas, and tabular data for business, reporting, and data analysis tasks, and may still be encountered in archived office documents. The format is obsolete, and modern spreadsheet applications may open it with limited fidelity; files from untrusted sources should still be handled with standard caution.

What are the magic bytes for .xld files?

The magic bytes for XLD files are 4D 69 63 72 6F 73 6F 66 74 20 45 78 63 65 6C 20 35 2E 30 20 57 6F 72 6B 73 68 65 65 74 at byte offset 2080. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .xld file?

To validate a .xld file, read the first bytes of the file and compare them against the known magic bytes (4D 69 63 72 6F 73 6F 66 74 20 45 78 63 65 6C 20 35 2E 30 20 57 6F 72 6B 73 68 65 65 74) at offset 2080. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .xld files?

The primary MIME type for .xld files is application/vnd.ms-excel.

Is it safe to open .xld files?

XLD (.xld) 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.