Windows animated cursor (.ani)
.ani file signature | application/octet-stream
Windows Animated Cursor (ANI) is a cursor animation file format developed by Microsoft for the Windows operating system. It is used to store animated mouse pointers and is supported by Windows, many desktop applications, and some graphics tools that handle cursor customization. The format is generally safe, though like other legacy Windows shell assets it should be opened from trusted sources because malformed files can affect cursor handling in older software.
Magic Bytes
Offset 0
52 49 46 46
Sources: Wikipedia, Gary Kessler
All Known Signatures
2 signature variants are documented for .ani files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 52 49 46 46 | 0 | Wikipedia, Gary Kessler |
| 41 43 4F 4E | 0 | Wikipedia |
Extension
.ani
MIME Type
application/octet-stream
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .ani files in Python
def is_ani(file_path: str) -> bool:
"""Check if file is a valid ANI by magic bytes."""
signature = bytes([0x52, 0x49, 0x46, 0x46])
with open(file_path, "rb") as f:
return f.read(4) == signatureHow to validate .ani files in Node.js
function isANI(buffer: Buffer): boolean {
const signature = Buffer.from([0x52, 0x49, 0x46, 0x46]);
return buffer.subarray(0, 4).equals(signature);
}How to validate .ani files in Go
func IsANI(data []byte) bool {
signature := []byte{0x52, 0x49, 0x46, 0x46}
if len(data) < 4 {
return false
}
return bytes.Equal(data[:4], signature)
}API Endpoint
/api/v1/ani
curl https://filesignature.org/api/v1/ani
See the full API documentation for all endpoints and parameters.
Related Formats
Frequently Asked Questions
What is a .ani file?
A .ani file is a Windows animated cursor file. Windows Animated Cursor (ANI) is a cursor animation file format developed by Microsoft for the Windows operating system. It is used to store animated mouse pointers and is supported by Windows, many desktop applications, and some graphics tools that handle cursor customization. The format is generally safe, though like other legacy Windows shell assets it should be opened from trusted sources because malformed files can affect cursor handling in older software.
What are the magic bytes for .ani files?
The magic bytes for Windows animated cursor files are 52 49 46 46 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .ani file?
To validate a .ani file, read the first bytes of the file and compare them against the known magic bytes (52 49 46 46) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .ani files?
There is no officially registered MIME type for .ani files. Systems typically use application/octet-stream as a generic fallback when handling this format.
Is it safe to open .ani files?
Windows animated cursor (.ani) 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.