123apps is a browser-based suite of video, audio, PDF, and file-conversion tools. Its apps are free to use with limits on file size and daily operations.
CloudConvert is a browser-based converter for more than 200 file formats, including documents, images, audio, video, archives, and specialist formats.
Zamzar is an online file conversion and compression service for documents, images, video, sound, and other formats. Its free web service has daily file and upload-size limits.
FreeConvert is an online file converter with more than 1,500 listed conversion types and a free allowance of 20 conversion minutes per day.
Ezgif is a free online toolset for making and editing animated GIFs, converting videos to animations, and working with other image formats.
Convertio is a browser-based service for converting files between supported formats, with optional settings for many conversion types.