ApplicationBinary

`application/octet-stream`

Binary Data

Reference for application/octet-stream, the generic MIME type for arbitrary binary data and unknown file types.

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Expected extensions: .bin, .exe, .dll, .so, .dylib

HTTP Content-Type Header

HTTP Header

Content-Type: application/octet-stream

Associated File Extensions

.bin.exe.dll.so.dylib

Quick Facts

MIME Type	application/octet-stream
Category	Application
Type	Binary
Extensions	.bin, .exe, .dll, .so, .dylib

Common Usage

application/octet-stream is the default MIME type for binary files when no more specific type is known. Browsers typically prompt users to download files served with this type.

It is used as a fallback for unknown file types and for forcing downloads of files that might otherwise be displayed inline.

Code Examples

HTML

<!-- Link or embed with explicit type -->
<link rel="stylesheet" href="file.bin" type="application/octet-stream">

<!-- Or for script/media elements -->
<script type="application/octet-stream" src="file.bin"></script>

Node.js

// Express.js
app.get('/file', (req, res) => {
  res.type('application/octet-stream');
  res.send(data);
});

// Node.js http
res.writeHead(200, { 'Content-Type': 'application/octet-stream' });

nginx

# nginx.conf — add to types block or use default
types {
    application/octet-stream  bin exe dll so dylib;
}

# Or set for a specific location
location /api/ {
    default_type application/octet-stream;
}