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AV1 Image File Format (.avif)

.avif file signature | image/avif

AV1 Image File Format (AVIF) is a still-image file format developed and maintained by the Alliance for Open Media, based on the AV1 video codec. It is used for web graphics, digital photography, and other images where efficient compression and support for modern image features are required. AVIF is a current standard and is generally considered safe, though, like any image format, files from untrusted sources should be handled with updated software.

Safe

Magic Bytes

Offset 4
66 74 79 70 61 76 69 66

Sources: Apache Tika, Gary Kessler

Extension

.avif

MIME Type

image/avif

Byte Offset

4

Risk Level

Safe

Validation Code

How to validate .avif files in Python

Python 
def is_avif(file_path: str) -> bool:
    """Check if file is a valid AVIF by magic bytes at offset 4."""
    signature = bytes([0x66, 0x74, 0x79, 0x70, 0x61, 0x76, 0x69, 0x66])
    with open(file_path, "rb") as f:
        f.seek(4)
        return f.read(8) == signature

How to validate .avif files in Node.js

Node.js 
function isAVIF(buffer: Buffer): boolean {
  const signature = Buffer.from([0x66, 0x74, 0x79, 0x70, 0x61, 0x76, 0x69, 0x66]);
  if (buffer.length < 12) return false;
  return buffer.subarray(4, 12).equals(signature);
}

How to validate .avif files in Go

Go 
func IsAVIF(data []byte) bool {
    signature := []byte{0x66, 0x74, 0x79, 0x70, 0x61, 0x76, 0x69, 0x66}
    if len(data) < 12 {
        return false
    }
    return bytes.Equal(data[4:12], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Related Formats

.cr3 .heic .heif .bmp .cr2 .dib

Frequently Asked Questions

What is a .avif file?

A .avif file is a AV1 Image File Format file. AV1 Image File Format (AVIF) is a still-image file format developed and maintained by the Alliance for Open Media, based on the AV1 video codec. It is used for web graphics, digital photography, and other images where efficient compression and support for modern image features are required. AVIF is a current standard and is generally considered safe, though, like any image format, files from untrusted sources should be handled with updated software.

What are the magic bytes for .avif files?

The magic bytes for AV1 Image File Format files are 66 74 79 70 61 76 69 66 at byte offset 4. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .avif file?

To validate a .avif file, read the first bytes of the file and compare them against the known magic bytes (66 74 79 70 61 76 69 66) at offset 4. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .avif files?

The primary MIME type for .avif files is image/avif.

Is it safe to open .avif files?

AV1 Image File Format (.avif) 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.