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Microsoft OneNote note (.one)

.one file signature | application/onenote;format=one

Microsoft OneNote note

Safe

Magic Bytes

Offset 0
7B 5C 52 E4

Sources: Apache Tika

All Known Signatures

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

Hex Signature Offset Sources
7B 5C 52 E4 0 Apache Tika
E4 52 5C 7B 8C D8 A7 4D AE B1 53 78 D0 29 96 D3 0 Gary Kessler

Extension

.one

MIME Type

application/onenote;format=one

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .one files in Python

Python 
def is_one(file_path: str) -> bool:
    """Check if file is a valid ONE by magic bytes."""
    signature = bytes([0x7B, 0x5C, 0x52, 0xE4])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .one files in Node.js

Node.js 
function isONE(buffer: Buffer): boolean {
  const signature = Buffer.from([0x7B, 0x5C, 0x52, 0xE4]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .one files in Go

Go 
func IsONE(data []byte) bool {
    signature := []byte{0x7B, 0x5C, 0x52, 0xE4}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .one file?

A .one file is a Microsoft OneNote note file. Microsoft OneNote note

What are the magic bytes for .one files?

The magic bytes for Microsoft OneNote note files are 7B 5C 52 E4 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .one file?

To validate a .one file, read the first bytes of the file and compare them against the known magic bytes (7B 5C 52 E4) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .one files?

The primary MIME type for .one files is application/onenote;format=one.

Is it safe to open .one files?

Microsoft OneNote note (.one) 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.