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Windows animated cursor (.ani)

.ani file signature | application/octet-stream

Windows animated cursor

Safe

Magic Bytes

Offset 0
52 49 46 46 41 43 4F 4E

Sources: Wikipedia

All Known Signatures

2 signature variants are documented for .ani files across multiple sources.

Hex Signature Offset Sources
52 49 46 46 41 43 4F 4E 0 Wikipedia
52 49 46 46 0 Gary Kessler

Extension

.ani

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .ani files in Python

Python
def is_ani(file_path: str) -> bool:
    """Check if file is a valid ANI by magic bytes."""
    signature = bytes([0x52, 0x49, 0x46, 0x46, 0x41, 0x43, 0x4F, 0x4E])
    with open(file_path, "rb") as f:
        return f.read(8) == signature

How to validate .ani files in Node.js

Node.js
function isANI(buffer: Buffer): boolean {
  const signature = Buffer.from([0x52, 0x49, 0x46, 0x46, 0x41, 0x43, 0x4F, 0x4E]);
  return buffer.subarray(0, 8).equals(signature);
}

How to validate .ani files in Go

Go
func IsANI(data []byte) bool {
    signature := []byte{0x52, 0x49, 0x46, 0x46, 0x41, 0x43, 0x4F, 0x4E}
    if len(data) < 8 {
        return false
    }
    return bytes.Equal(data[:8], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .ani file?

A .ani file is a Windows animated cursor file. Windows animated cursor

What are the magic bytes for .ani files?

The magic bytes for Windows animated cursor files are 52 49 46 46 41 43 4F 4E 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 41 43 4F 4E) 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.