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OTC magic bytes (.otc)

.otc file signature: 50 4B | application/vnd.oasis.opendocument.chart-template

OpenDocument Chart Template (OTC) is a template file format defined by OASIS for creating chart documents in the OpenDocument family. It is used in office suites such as LibreOffice and Apache OpenOffice to store reusable chart layouts, styles, and default settings for spreadsheet and presentation documents. The format is generally considered safe, though, like other office files, it should be opened cautiously if received from untrusted sources.

Safe

Magic Bytes

Offset 0
50 4B

Sources: Apache Tika

Extension

.otc

MIME Type

application/vnd.oasis.opendocument.chart-template

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .otc files in Python

Python 
def is_otc(file_path: str) -> bool:
    """Check if file is a valid OTC by magic bytes."""
    signature = bytes([0x50, 0x4B])
    with open(file_path, "rb") as f:
        return f.read(2) == signature

How to validate .otc files in Node.js

Node.js 
function isOTC(buffer: Buffer): boolean {
  const signature = Buffer.from([0x50, 0x4B]);
  return buffer.subarray(0, 2).equals(signature);
}

How to validate .otc files in Go

Go 
func IsOTC(data []byte) bool {
    signature := []byte{0x50, 0x4B}
    if len(data) < 2 {
        return false
    }
    return bytes.Equal(data[:2], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .otc file?

A .otc file is identified by the magic bytes 50 4B at byte offset 0. OpenDocument Chart Template (OTC) is a template file format defined by OASIS for creating chart documents in the OpenDocument family. It is used in office suites such as LibreOffice and Apache OpenOffice to store reusable chart layouts, styles, and default settings for spreadsheet and presentation documents. The format is generally considered safe, though, like other office files, it should be opened cautiously if received from untrusted sources.

What are the magic bytes for .otc files?

The magic bytes for OTC (.otc) files are 50 4B at byte offset 0. These bytes identify the file format more reliably than the extension alone.

How do I validate a .otc file?

To validate a .otc file, read the first bytes of the file and compare them against the known magic bytes (50 4B) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .otc files?

The primary MIME type for .otc files is application/vnd.oasis.opendocument.chart-template.

Is it safe to open .otc files?

OTC (.otc) 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.