Content-Disposition Builder: UTF-8 Download Filenames
Generate attachment or inline headers with an explicit ASCII fallback and UTF-8 filename*, rejecting header-injection controls locally.
Enabling local controls…
1. Filename and presentation
Page-memory only; no requests or files sent. Each filename: 1,024 UTF-16 characters; input: 1 MiB UTF-8; output: 16 KiB. CRLF, controls and unpaired surrogates are rejected. Filenames are never silently replaced or sanitized.
Printable ASCII only. Leave blank for an ASCII filename to reuse it exactly; international names require your explicit fallback. Spaces, quotes, backslashes and percent signs are encoded per standard; spaces never become +.
A filename is advisory, not a safe filesystem path. Recipients still handle directory components, reserved names, overwrites, OS rules and content. attachment does not guarantee a download; inline does not make content safe. Set Content-Type and authorization separately.
2. ASCII and UTF-8 header
Enter filenames or load a sample, then build.
How to use this tool
Enter the desired filename and ASCII fallback, choose disposition and inspect quoted and extended values. Copy the header, then test the receiving browser's download behavior.
When not to use it
A suggested filename is not a safe filesystem path. Browser policy, file extensions and server content still require separate checks; the tool does not download a remote file.
Read the guide →