TonniTools is built to run locally in your browser. Since no data ever leaves your device, everything works, even without internet.
Drop in one or many videos and convert them to MP4, MOV, or WebM — entirely in your browser. Choose Original to keep original quality (compatible streams are copied as-is), or High, Medium, or Low to re-encode and shrink the file. Resolution and duration stay the same. Supports common inputs including MP4, MOV, WebM, and MKV. Pick an output format and quality, convert the batch, then download files individually or all at once as a ZIP. Nothing is uploaded, and conversion works offline once the page is loaded.