CALS raster bitmap file (.cal)
.cal file signature | application/octet-stream
CALS raster bitmap file
Magic Bytes
Offset 0
53 75 70 65 72 43 61 6C 63
Sources: Gary Kessler
All Known Signatures
3 signature variants are documented for .cal files across multiple sources.
| Hex Signature | Offset | Sources |
|---|---|---|
| 53 75 70 65 72 43 61 6C 63 | 0 | Gary Kessler |
| 73 72 63 64 6F 63 69 64 3A | 0 | Gary Kessler |
| B5 A2 B0 B3 B3 B0 A5 B5 | 0 | Gary Kessler |
Extension
.cal
MIME Type
application/octet-stream
Byte Offset
0
Risk Level
Safe
Validation Code
How to validate .cal files in Python
def is_cal(file_path: str) -> bool:
"""Check if file is a valid CAL by magic bytes."""
signature = bytes([0x53, 0x75, 0x70, 0x65, 0x72, 0x43, 0x61, 0x6C, 0x63])
with open(file_path, "rb") as f:
return f.read(9) == signatureHow to validate .cal files in Node.js
function isCAL(buffer: Buffer): boolean {
const signature = Buffer.from([0x53, 0x75, 0x70, 0x65, 0x72, 0x43, 0x61, 0x6C, 0x63]);
return buffer.subarray(0, 9).equals(signature);
}How to validate .cal files in Go
func IsCAL(data []byte) bool {
signature := []byte{0x53, 0x75, 0x70, 0x65, 0x72, 0x43, 0x61, 0x6C, 0x63}
if len(data) < 9 {
return false
}
return bytes.Equal(data[:9], signature)
}API Endpoint
/api/v1/cal
curl https://filesignature.org/api/v1/cal
See the full API documentation for all endpoints and parameters.
Frequently Asked Questions
What is a .cal file?
A .cal file is a CALS raster bitmap file file. CALS raster bitmap file
What are the magic bytes for .cal files?
The magic bytes for CALS raster bitmap file files are 53 75 70 65 72 43 61 6C 63 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.
How do I validate a .cal file?
To validate a .cal file, read the first bytes of the file and compare them against the known magic bytes (53 75 70 65 72 43 61 6C 63) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.
What is the MIME type for .cal files?
There is no officially registered MIME type for .cal files. Systems typically use application/octet-stream as a generic fallback when handling this format.
Is it safe to open .cal files?
CALS raster bitmap file (.cal) 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.