Free Online Video Converter — Runs in Your Browser
Turn WebM into MP4, MOV into MP4, MKV into MP4 or HEVC into H.264 — or pull the audio out as MP3, M4A or WAV, keeping just the part of the clip you actually need. Your device does the decoding and encoding, so there is no file-size limit, no queue, no watermark and no account.
Convert a Video File
Pick a file, choose a target, press convert. MP4 (H.264 + AAC) plays on essentially everything — iPhone, QuickTime, Premiere, Instagram, TikTok, a TV stick.
Files that are already in a compatible codec are re-wrapped rather than re-encoded — a MOV or MKV that already holds H.264/AAC becomes an MP4 in about a second with no quality lost. WebM (VP8/VP9) to MP4 is a genuine re-encode, done by your device's video hardware where the browser exposes it. The audio-only targets skip the picture entirely: WAV needs no encoder at all, while MP3 and (on browsers without a built-in one) AAC are produced by small bundled encoders that are downloaded only the first time you ask for that format.
Three Steps, No Upload
- 1
Pick the video
Drop it on the box above or choose it from the file picker. The page reads the file's container and codecs locally, then tells you exactly what the conversion will change — including when nothing needs re-encoding at all.
- 2
Choose the target
MP4 (H.264 + AAC) is the safe answer for anything that has to play on someone else's device. WebM (VP9 + Opus) is the smaller option for a web page or an embed. Downscale to 720p or 480p if you also want a smaller file.
- 3
Convert and download
The file is re-encoded in the tab, with a progress bar you can cancel at any point. When it finishes you can play the result back right there before saving it, so you know it works before you hand it to anyone.
What People Actually Convert
Each guide below opens this tool with the right target already selected.
WebM to MP4
Screen recordings and browser captures land as WebM, which iPhones, QuickTime and most editors refuse to open. Converting drops VP8/VP9 video into H.264 so it plays anywhere.
MOV to MP4
A QuickTime file from an iPhone or a Mac screen recording is often already H.264 and AAC inside a MOV wrapper — so this is a re-wrap, which is near-instant and completely lossless.
MKV to MP4
Matroska is the container of choice for downloaded and archived video. Its contents are frequently H.264/AAC already, so the same lossless re-wrap usually applies.
HEVC to H.264
Modern phones record H.265 to save space, and then half the world's software won't play it. Converting to H.264 is the standard fix for that "this file can't be played" message.
MP4 to WebM
The other direction: turning a finished MP4 into a smaller WebM for a web page, a loop, or a client who needs open, royalty-free codecs.
Compress a Video
Keep the container and the codecs, drop the resolution to 720p or 480p and pick a lower quality setting — the same engine handles it, so it needs no separate tool.
Video to MP3
Pulling the soundtrack out of a video: it becomes an MP3, M4A or WAV you can drop into a player, a podcast or a message, with the picture discarded entirely.
MP4, WebM — or Just the Audio
MP4 — H.264 + AAC
The compatibility choice. Every iPhone, Android phone, camera, TV, editor and social platform accepts it, including Instagram, TikTok and YouTube uploads. Slightly larger files than WebM at the same visual quality.
WebM — VP9 + Opus
The web choice. Better compression than H.264 at the same quality, royalty-free, and perfect for a video tag on a page. Apple devices and most desktop editors will not open it, so keep the MP4 if it has to travel.
Resolution
Keep original whenever you can. Choosing 1080p, 720p or 480p always means re-encoding, because the frames have to be rescaled — that is what makes it the biggest lever on file size, and the only setting here that costs quality by design.
Quality
Only applies when a re-encode actually happens. Balanced is the default for a reason; High is worth picking when the source is already poor-quality and you would rather not stack one round of compression on top of another.
Audio only: MP3, M4A or WAV
Switching to an audio target throws the picture away and keeps the sound. MP3 is the one that plays literally everywhere; M4A gives better quality for the same size; WAV is uncompressed and needs no encoder at all, so it works in every browser.
Trim while converting
The In and Out fields take seconds and convert only that section — handy for pulling one song out of a long recording, or for splitting a file too large to hold in memory into two passes instead of one.
No Upload, No Queue, Nothing To Pay For
Your file never leaves the device
There is no upload step and no server holding your footage. Confidential screen recordings, client work and personal video stay on the machine they started on — which is usually the whole reason someone hesitates before typing a file into a converter site.
No size cap, because there is no upload
Most online converters cap free conversions, then sell you a bigger limit. Nothing here is metered: the file goes straight from your disk into your own video hardware and back out again, so there is no queue to join and no upload to wait through.
Hardware-accelerated where possible
The encode runs through WebCodecs, which uses the video encoder your device already has for recording and video calls. On a modern laptop that means a re-encode is often faster than playing the clip back in real time.
Free, and staying that way
This page is a tool attached to a browser-based computer-vision app, not a business with a conversion quota to sell. There is no signup, no watermark, and no paywall waiting behind a third conversion.
Honest about the trade-off
Because the work happens on your machine, it is your machine's speed that decides how long it takes — a phone will be slower than a laptop. You also need a recent browser: Chrome, Edge, Safari 16.4+ or Firefox 130+, since that is where WebCodecs landed.
Then edit it in the same ecosystem
Once a clip is in MP4, the Vis Exo app can open it and put motion tracking, pose skeletons, trails, LUT grades and captions on top of it — free, and in the browser too.
Video Converter FAQ
Is this video converter really free?
Yes. There is no account, no watermark, no export limit and no paid tier. The conversion runs in your browser instead of on a server, so there is nothing for us to meter or charge for.
Are my videos uploaded to a server?
No. The file is never sent anywhere. It is read and re-encoded by your own device, and the converted file is handed straight back to you as a download.
How do I convert WebM to MP4?
Choose the WebM file, leave the target set to MP4 (H.264 + AAC) and press Convert Video. WebM's VP8 or VP9 video has to be re-encoded, because MP4 players such as QuickTime, iPhones and most video editors do not support it.
Why is MP4 the safest choice?
H.264 video plus AAC audio in an MP4 container is the combination every iPhone, Android phone, video editor, smart TV and social platform accepts. WebM files are smaller for web use, but Apple devices and most desktop editors will not open them.
Will converting my video reduce the quality?
Only if it actually re-encodes. If your file already contains H.264 or AAC, as many MOV and MKV files do, it is re-wrapped without touching the video data, so nothing is lost. When a re-encode is unavoidable, keeping the original resolution and picking High quality stays as close to the source as the browser can get.
Is there a file-size limit?
There is no upload limit and no paid cap, because nothing is uploaded. Files are processed in memory, though, so a very large file of roughly 1GB or more can fail on a device with little RAM. Trimming the clip first or converting at 720p keeps it comfortable.
Which browsers can run the converter?
Any recent Chrome, Edge, Safari 16.4 or newer, or Firefox 130 or newer, on desktop or mobile. Firefox has no built-in AAC encoder, so there this page quietly loads a small bundled one to keep the audio in your MP4 — that is the only case where converting needs an extra download.
Can I convert a video to MP3, or extract just the audio?
Yes. Choose one of the audio-only targets and the picture is discarded, leaving the soundtrack as an MP3, M4A or WAV. MP3 plays on essentially everything, M4A sounds better for the same file size, and WAV is uncompressed and needs no bundled encoder, so it works in every browser.
Can I convert only part of a video?
Yes. The In and Out fields take a start and an end time in seconds, and only that section is converted — the output begins at zero, so it plays as a clip in its own right. Leave both blank to convert the whole file.
Converted it? Now track something in it.
Vis Exo adds blob tracking, pose skeletons, trails, LUT grades and captions to the same MP4 — free, and entirely in your browser.