Video Converter
Convert MOV, MKV, AVI, WebM and more to MP4 — entirely in your browser. Your file is never uploaded to a server; the whole conversion runs on your device. Free, private and watermark-free.
- No login required
- Files never stored
- Free forever
Your video is processed in your browser and never uploaded.
Video converter
Convert video to MP4 without uploading it
Most online converters upload your video to their servers first, which is slow and leaks your file. This converter runs entirely in your browser using WebAssembly, so your clip never leaves your device. Pick a video in almost any format — MOV, MKV, AVI, WebM — and we re-encode it to a clean, widely-compatible MP4 (or MOV/MKV) you can save instantly.
Pick the file you want to convert
Click Choose a video and select any file up to 200 MB. The browser reads it locally, so there is no upload wait even for a large MKV or MOV.
Choose your target format
Use the Convert to menu to select MP4, MOV or MKV. If you are not sure which you need, MP4 is the right answer — it is the one format that plays everywhere without argument.
Convert and download
Press Convert. The engine loads on first use (about 31 MB, then cached) and a progress percentage tracks the encode. Preview the result inline, then download it with your original filename and the new extension.
What conversion actually does here
This is a real conversion, not a container swap. The video is decoded and re-encoded to H.264 at CRF 23 with the veryfast preset, and the audio is re-encoded to AAC, before being written into the container you chose. CRF 23 is a high-quality setting — the point of this tool is compatibility, not shrinking, so the output is meant to look essentially the same as your source. Re-encoding rather than copying the streams is deliberate: it guarantees the file plays regardless of what exotic codec was inside the original. A consequence worth knowing is that the output size is determined by CRF 23 rather than by your input, so converting a heavily compressed file can produce a larger one. If your goal is a smaller file rather than a different format, the video compressor is the tool you want.
MP4, MOV and MKV — which to choose
All three outputs contain the same H.264 video and AAC audio; only the container differs, and the container mostly decides which software will open the file without complaining. MP4 is the universal choice: every phone, browser, TV, editor and social platform accepts it, and it is what you should pick unless you have a specific reason not to. MOV is Apple's container and is the smoothest option if the file is heading into Final Cut Pro, iMovie or QuickTime, though modern versions of all three read MP4 happily too. MKV is the flexible open container favoured by desktop players like VLC and by media servers such as Plex and Jellyfin; it is excellent for local archives but is not accepted by most social platforms or by iOS out of the box, so avoid it for anything you intend to share.
Which input formats are supported
The engine reads far more formats than it writes. Common sources include MOV files from iPhones and professional cameras, MP4 from Android and almost everything else, MKV from desktop recorders and downloads, AVI and WMV from older Windows software, WebM and OGV from browser-based recorders, FLV from legacy archives, and 3GP from old phones. The codec inside matters as little as the container: H.264, HEVC/H.265, MPEG-4, VP8, VP9, AV1 and older MPEG-2 material all decode fine. This is what makes the tool useful for HEVC in particular — iPhones record in HEVC by default, and converting to H.264 MP4 is usually the quickest way to fix a video that Windows, an older TV or an editing program refuses to open.
How long a conversion takes
Because every frame is decoded and re-encoded, conversion time scales with length and resolution rather than with file size. The engine runs single-threaded for maximum browser compatibility, so a minute of 1080p typically takes a few minutes on a current laptop, longer on a phone, and considerably longer for 4K. HEVC and AV1 sources decode more slowly than H.264 ones, so an iPhone HEVC clip takes a little longer than an equivalent H.264 file. Keep the tab in the foreground on mobile, since browsers throttle background tabs and will stall the encode.
If something goes wrong
If the conversion fails, the most likely cause is browser memory rather than an unsupported format — long or 4K files are the usual culprits, and trimming the clip first almost always resolves it. Files over 200 MB are rejected before conversion begins. If the converted file plays with picture but no sound, the source probably used an audio codec the core cannot decode; extracting the audio separately will confirm it. If your output ended up larger than the input, that is CRF 23 doing its job as a quality-preserving setting — use the compressor instead when size is the goal.
Private by design
Because the conversion happens on your device, your video is never sent anywhere and nothing is stored. Online converters are the category of tool most likely to ask you to hand over a file and wait, and the files people convert are frequently the ones they would least like to upload — raw camera footage, screen recordings of internal systems, unreleased edits. Here there is no server copy to worry about, no retention policy to read, and no account. It works on desktop and modern mobile browsers, and the engine downloads once on first use.
Frequently asked questions
Answers to the most common questions about using these free video & audio tools.
MP4, MOV or MKV. All three are written with H.264 video and AAC audio; MP4 is the most compatible and plays on virtually every device, browser and app.