Media Converter
Free online audio and video format conversion and trimming tool: convert audio between MP3, WAV, M4A, AAC, FLAC, OGG; change video containers (e.g., mkv→mp4) or re-encode, and trim by time. All processing happens locally in your browser; the tool is completely free.
FAQ
Container-only conversion (e.g., mkv→mp4) doesn't re-compress the video, completing instantly with no loss, but requires compatible source encoding; re-encoding performs actual transcoding, is more universal but slower in the browser, suitable for short clips.
Video encoding is computationally intensive, and browser single-threaded processing is slow. To prevent long delays, re-encoding is limited to ≤5 minutes duration and ≤500MB file size; you can first trim the clip before converting.
In container-only/copy-stream mode, trimming aligns to the nearest keyframe, which may cause slight offset at start; for frame-accurate trimming, use the "re-encoding" mode.
Audio: MP3, WAV, M4A (AAC), AAC, FLAC, OGG; Video containers: MP4, MKV, MOV, WebM. Converting to WebM requires re-encoding since it uses different codecs than MP4.