Does this actually convert the file, e.g. .docx to .pdf?

No — it only renames the extension text; the file content is untouched. Use it to fix a wrong extension, not to convert a file format.

Does this tool upload my filename anywhere?

No — it runs entirely in your browser.

Swap a filename’s extension while keeping the rest of the name.

Top ad slot

Filename

New extension

Bottom ad slot

1
Type or paste a filename

e.g. "report.docx".
2
Enter the new extension

With or without the leading dot — e.g. "pdf" or ".pdf".
3
Copy the result

The base name stays, only the extension swaps.

Does this actually convert the file, e.g. .docx to .pdf?: No — it only renames the extension text; the file content is untouched. Use it to fix a wrong extension, not to convert a file format.
Does this tool upload my filename anywhere?: No — it runs entirely in your browser.