Windows Help index file magic bytes (.gid)
.gid file signature: 3F 5F 03 00 | application/octet-stream
Windows Help index file (GID) is a legacy index file format associated with Microsoft Windows Help and maintained as part of the Windows help system. It was used to support indexed searching and navigation within compiled help files and related help viewers. The format is largely obsolete today and is generally safe, though it may appear in older software installations or archived documentation.
Magic Bytes
Offset 0
3F 5F 03 00
Sources: Gary Kessler
All Known Signatures
2 signature variants are documented for .gid files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 3F 5F 03 00 | 0 | Gary Kessler |
| 4C 4E 02 00 | 0 | Gary Kessler |
Validation Code
How to validate .gid files in Python
def is_gid(file_path: str) -> bool:
"""Check if file is a valid GID by magic bytes."""
signature = bytes([0x3F, 0x5F, 0x03, 0x00])
with open(file_path, "rb") as f:
return f.read(4) == signatureHow to validate .gid files in Node.js
function isGID(buffer: Buffer): boolean {
const signature = Buffer.from([0x3F, 0x5F, 0x03, 0x00]);
return buffer.subarray(0, 4).equals(signature);
}How to validate .gid files in Go
func IsGID(data []byte) bool {
signature := []byte{0x3F, 0x5F, 0x03, 0x00}
if len(data) < 4 {
return false
}
return bytes.Equal(data[:4], signature)
}API Endpoint
/api/v1/gid
curl https://filesignature.org/api/v1/gid
See the full API documentation for all endpoints and parameters.
Frequently Asked Questions
What is a .gid file?
A .gid file is a Windows Help index file. Windows Help index file (GID) is a legacy index file format associated with Microsoft Windows Help and maintained as part of the Windows help system. It was used to support indexed searching and navigation within compiled help files and related help viewers. The format is largely obsolete today and is generally safe, though it may appear in older software installations or archived documentation.
What are the magic bytes for .gid files?
The magic bytes for Windows Help index file (.gid) files are 3F 5F 03 00 at byte offset 0. These bytes identify the file format more reliably than the extension alone.
How do I validate a .gid file?
To validate a .gid file, read the first bytes of the file and compare them against the known magic bytes (3F 5F 03 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 .gid files?
There is no officially registered MIME type for .gid files. Systems typically use application/octet-stream as a generic fallback when handling this format.
Is it safe to open .gid files?
Windows Help index file (.gid) 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.