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FLIF (.flif)

.flif file signature | application/octet-stream

Free Lossless Image Format (FLIF) is a lossless raster image format developed by the FLIF project, led by Pieter Wuille and Kornel Lesiński. It is used for storing still images with efficient compression, particularly in software workflows that prioritize exact pixel preservation and archival storage. FLIF is a legacy format and is no longer actively developed, so support may be limited in modern applications, though the format itself poses no special security concerns.

Safe

Magic Bytes

Offset 0
46 4C 49 46

Sources: Wikipedia

Extension

.flif

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .flif files in Python

Python 
def is_flif(file_path: str) -> bool:
    """Check if file is a valid FLIF by magic bytes."""
    signature = bytes([0x46, 0x4C, 0x49, 0x46])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .flif files in Node.js

Node.js 
function isFLIF(buffer: Buffer): boolean {
  const signature = Buffer.from([0x46, 0x4C, 0x49, 0x46]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .flif files in Go

Go 
func IsFLIF(data []byte) bool {
    signature := []byte{0x46, 0x4C, 0x49, 0x46}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .flif file?

A .flif file is identified by the magic bytes 46 4C 49 46 at byte offset 0. Free Lossless Image Format (FLIF) is a lossless raster image format developed by the FLIF project, led by Pieter Wuille and Kornel Lesiński. It is used for storing still images with efficient compression, particularly in software workflows that prioritize exact pixel preservation and archival storage. FLIF is a legacy format and is no longer actively developed, so support may be limited in modern applications, though the format itself poses no special security concerns.

What are the magic bytes for .flif files?

The magic bytes for FLIF files are 46 4C 49 46 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .flif file?

To validate a .flif file, read the first bytes of the file and compare them against the known magic bytes (46 4C 49 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 .flif files?

There is no officially registered MIME type for .flif files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .flif files?

FLIF (.flif) 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.