Add missing file extensions
Detect signatures and suggest extensions.
Add files or an archive
Drop files here. They will not be uploaded.
Result
How does Add missing file extensions work?
Choose a file or a set of files. The app reads them directly in the browser, applies safety limits and performs the selected operation locally. The source file remains unchanged.
Security and limitations
Archives are checked for unsafe paths, extreme compression ratios and excessive entry counts. Archiwum does not execute extracted files and is not an antivirus scanner.
Privacy
File names and contents are not sent to our own server. Heavier formats use a local WebAssembly module that consumes the user device resources rather than DreamHost resources.
FAQ
Is the file uploaded?
No. The file is read by your browser on your device.
Can I cancel the operation?
Yes. The Cancel button stops the current task and releases resources.
Does the result modify the source file?
No. You download a new file or report.
Related tools
Batch rename files
Apply rules and download a new ZIP with safe file names.
✏️Add filename prefix
Add common text before every file name.
✏️Add filename suffix
Add text before the extension.
✏️Number files
Add numbers with leading zeros.
✏️Replace spaces in filenames
Replace spaces with hyphens or underscores.
✏️Remove diacritics from filenames
Create ASCII file names with conflict preview.