application/*
application/octet-stream
File extensions: .bin
Generic arbitrary binary data — the ultimate fallback.
What is application/octet-stream?
application/octet-stream is the catch-all media type for arbitrary binary data. When a server does not know or does not want to declare the specific type of a file, this triggers a plain download in every browser.
Typical usage
Forcing file downloads, streaming unknown binary payloads, generic file transfer.
Common gotchas
Using octet-stream when a more specific type exists prevents proper handling (e.g. previews, correct extensions). Always send the most specific MIME type you know.
HTTP header example
Response header
Content-Type: application/octet-stream; charset=utf-8Reference
RFC 2046 §4.5.1
Frequently asked questions
What is the application/octet-stream MIME type?
application/octet-stream is the catch-all media type for arbitrary binary data. When a server does not know or does not want to declare the specific type of a file, this triggers a plain download in every browser.
What file extension does application/octet-stream use?
Files served as application/octet-stream typically use the extension .bin. The most common is .bin.
How do I set the Content-Type for application/octet-stream?
Send the HTTP response header Content-Type: application/octet-stream; charset=utf-8. Forcing file downloads, streaming unknown binary payloads, generic file transfer.
Is application/octet-stream an official MIME type?
Yes. application/octet-stream is officially registered with IANA (RFC 2046 §4.5.1), so standards-conformant clients recognize it.
What are common mistakes with application/octet-stream?
Using octet-stream when a more specific type exists prevents proper handling (e.g. previews, correct extensions). Always send the most specific MIME type you know.