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Visual Studio Solution User Options subheader (.suo)

.suo file signature | application/octet-stream

Visual Studio Solution User Options (.suo) is a Microsoft Visual Studio file format used to store user-specific solution data and is maintained by Microsoft as part of the Visual Studio development environment. It supports settings such as window layout, breakpoints, debugging state, and other per-user preferences associated with a solution. The format is generally safe and local to a developer’s workspace, although it is often excluded from source control because it may contain machine-specific data.

Safe

Magic Bytes

Offset 512
FD FF FF FF 04

Sources: Gary Kessler

Extension

.suo

MIME Type

application/octet-stream

Byte Offset

512

Risk Level

Safe

Validation Code

How to validate .suo files in Python

Python 
def is_suo(file_path: str) -> bool:
    """Check if file is a valid SUO by magic bytes at offset 512."""
    signature = bytes([0xFD, 0xFF, 0xFF, 0xFF, 0x04])
    with open(file_path, "rb") as f:
        f.seek(512)
        return f.read(5) == signature

How to validate .suo files in Node.js

Node.js 
function isSUO(buffer: Buffer): boolean {
  const signature = Buffer.from([0xFD, 0xFF, 0xFF, 0xFF, 0x04]);
  if (buffer.length < 517) return false;
  return buffer.subarray(512, 517).equals(signature);
}

How to validate .suo files in Go

Go 
func IsSUO(data []byte) bool {
    signature := []byte{0xFD, 0xFF, 0xFF, 0xFF, 0x04}
    if len(data) < 517 {
        return false
    }
    return bytes.Equal(data[512:517], signature)
}

API Endpoint

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

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .suo file?

A .suo file is a Visual Studio Solution User Options subheader file. Visual Studio Solution User Options (.suo) is a Microsoft Visual Studio file format used to store user-specific solution data and is maintained by Microsoft as part of the Visual Studio development environment. It supports settings such as window layout, breakpoints, debugging state, and other per-user preferences associated with a solution. The format is generally safe and local to a developer’s workspace, although it is often excluded from source control because it may contain machine-specific data.

What are the magic bytes for .suo files?

The magic bytes for Visual Studio Solution User Options subheader files are FD FF FF FF 04 at byte offset 512. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .suo file?

To validate a .suo file, read the first bytes of the file and compare them against the known magic bytes (FD FF FF FF 04) at offset 512. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .suo files?

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

Is it safe to open .suo files?

Visual Studio Solution User Options subheader (.suo) 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.