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WARC (.warc)

.warc file signature | application/warc

Safe

Magic Bytes

Offset 0
57 41 52 43 2F

Sources: Apache Tika

Extension

.warc

MIME Type

application/warc

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .warc files in Python

Python 
def is_warc(file_path: str) -> bool:
    """Check if file is a valid WARC by magic bytes."""
    signature = bytes([0x57, 0x41, 0x52, 0x43, 0x2F])
    with open(file_path, "rb") as f:
        return f.read(5) == signature

How to validate .warc files in Node.js

Node.js 
function isWARC(buffer: Buffer): boolean {
  const signature = Buffer.from([0x57, 0x41, 0x52, 0x43, 0x2F]);
  return buffer.subarray(0, 5).equals(signature);
}

How to validate .warc files in Go

Go 
func IsWARC(data []byte) bool {
    signature := []byte{0x57, 0x41, 0x52, 0x43, 0x2F}
    if len(data) < 5 {
        return false
    }
    return bytes.Equal(data[:5], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .warc file?

A .warc file is a WARC file.

What are the magic bytes for .warc files?

The magic bytes for WARC files are 57 41 52 43 2F at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .warc file?

To validate a .warc file, read the first bytes of the file and compare them against the known magic bytes (57 41 52 43 2F) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .warc files?

The primary MIME type for .warc files is application/warc.

Is it safe to open .warc files?

WARC (.warc) 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.