Online video converter for local formats and audio

Choose by task

Choose a video converter by the output you need

Use MOV to MP4 for compatible iPhone or QuickTime clips, MKV to MP4 for a supported Matroska primary track, and WebM to MP4 for browser recordings that need wider playback. MP4 to WebM creates a VP9/Opus web alternative. Video to GIF creates a short silent animation, while GIF to MP4 creates an efficient video copy.

Audio pages discard video and keep the primary audio track. MP4 to MP3 targets the specific MP4 workflow. Video to MP3 covers several local containers. Both prefer true MP3 and disclose an AAC-in-M4A fallback when MP3 encoding cannot initialize. A file extension should always match the actual container and codec.

Container and codec are not the same thing

MP4, MOV, MKV and WebM are containers. Each can hold one or more media streams encoded with codecs such as H.264, HEVC, VP9, AV1, AAC, Opus or DTS. Changing a container name does not make an incompatible codec playable.

The converter reads the container, decodes supported source streams, and encodes the requested output. Browser compatibility therefore depends on what is inside the file. An MKV with H.264/AAC may work while another MKV with HEVC/DTS fails. The same difference explains why some professional MOV files cannot be processed even though ordinary iPhone MOV clips can.

When conversion changes quality, size and metadata

Most conversions on this site re-encode media. Re-encoding can change visual detail, audio quality, color handling, metadata and file size. It does not guarantee a smaller file, and “without losing quality” cannot be promised for a lossy transcode.

Keep the original container as the master. Convert for a real compatibility reason, then compare the output. Check duration, dimensions, orientation, speech, music, subtitles and the desired audio language. Extra MKV tracks, chapters, timecode and specialist metadata are not guaranteed to survive a simple primary-track conversion.

Local conversion privacy and browser limits

The file is selected from your device and processed locally. There is no encode upload queue and no third-party URL downloader. This makes the converter useful for private drafts, but local work still uses CPU, memory and temporary browser storage.

Desktop Chrome or Edge is recommended. Long 4K footage and multi-gigabyte camera sources can exceed tab resources. Closing other tabs, using a shorter source or creating a compatible H.264/AAC MP4 in the original app can help. A codec error cannot be solved by repeatedly renaming the extension.

How to verify a converted file before delivery

Confirm the selected page matches the desired output. Start with a short representative source when testing an unfamiliar codec. Let the job finish without closing the tab, then check the extension and MIME behavior of the download.

Play the beginning, middle and end. Seek to several points, confirm audio language and synchronization, and compare file size without assuming smaller means better. For WebM, test the actual target browsers. For GIF, check colors and loop speed. For MP3 extraction, confirm whether the download is MP3 or the clearly labeled M4A fallback.