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About this tool
Clean file names of spaces, symbols, accents and reserved words that break government portal and legacy system uploads.
This sanitiser rewrites any file name into the POSIX portable filename character set — letters, digits, dot, hyphen and underscore (POSIX.1-2017 §3.282) — which is the safest alphabet for government portals, legacy Java/ASP upload validators, URLs and every operating system. It replaces spaces and symbols, transliterates accents (é becomes e), lowercases the extension, avoids Windows reserved device names like CON and PRN, and truncates long names while always preserving the extension. It is built for applicants whose scans keep bouncing off upload forms with vague errors.
Open File Name Sanitiser For Portals on AltFTool — it loads instantly in your browser.
Upload or drag in the file you want to work with.
Adjust the settings and preview the result.
Download the finished file to your device.
Spaces, symbols, accents, reserved names, hidden-file dots and length are all fixed together.
Lists exactly which problems the original name had, so uploads stop failing mysteriously.
Truncation shortens only the base name, and the extension is lowercased for strict validators.
Many portals run old server-side validators that whitelist only letters, digits and a few separators, and spaces also break naive URL handling when the file is served back. Replacing each space with an underscore or hyphen — as this tool does — is the standard fix.
The POSIX portable filename character set: uppercase and lowercase A-Z, digits 0-9, dot, hyphen and underscore — 65 characters in total. A name built only from these works on Windows, macOS, Linux, in URLs and past effectively every upload validator.
CON, PRN, AUX, NUL, COM1-COM9 and LPT1-LPT9 are reserved DOS device names, and Windows refuses them as base file names regardless of extension — con.pdf is as invalid as con. The sanitiser appends a separator character to any such base name so the file stays usable everywhere.
No — a rename changes only the label the filesystem stores, never the bytes inside, so a renamed photo has identical quality and file size. If a portal complains about size or format rather than the name, you need a converter or compressor instead.