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Adobe Portable Document Format (.ai)

.ai file signature | application/postscript

Adobe Illustrator Artwork (AI) is a vector graphics file format created and maintained by Adobe for use in Illustrator. It is commonly used for logos, illustrations, print layouts, and other editable graphic assets, and may also be embedded in publishing and design workflows. AI files can contain PostScript or PDF data, so files from untrusted sources should be opened with current software and caution.

Safe

Magic Bytes

Offset 0
25 50 44 46

Sources: Gary Kessler

Extension

.ai

MIME Type

application/postscript, application/illustrator

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .ai files in Python

Python 
def is_ai(file_path: str) -> bool:
    """Check if file is a valid AI by magic bytes."""
    signature = bytes([0x25, 0x50, 0x44, 0x46])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .ai files in Node.js

Node.js 
function isAI(buffer: Buffer): boolean {
  const signature = Buffer.from([0x25, 0x50, 0x44, 0x46]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .ai files in Go

Go 
func IsAI(data []byte) bool {
    signature := []byte{0x25, 0x50, 0x44, 0x46}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Related Formats

.eps .epsf .cdr .vsdx .cgm .dwg

Frequently Asked Questions

What is a .ai file?

A .ai file is a Adobe Portable Document Format file. Adobe Illustrator Artwork (AI) is a vector graphics file format created and maintained by Adobe for use in Illustrator. It is commonly used for logos, illustrations, print layouts, and other editable graphic assets, and may also be embedded in publishing and design workflows. AI files can contain PostScript or PDF data, so files from untrusted sources should be opened with current software and caution.

What are the magic bytes for .ai files?

The magic bytes for Adobe Portable Document Format files are 25 50 44 46 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .ai file?

To validate a .ai file, read the first bytes of the file and compare them against the known magic bytes (25 50 44 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 .ai files?

The primary MIME type for .ai files is application/postscript. Additional MIME types include: application/postscript, application/illustrator.

Is it safe to open .ai files?

Adobe Portable Document Format (.ai) 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.