Free Online Video Converter (No Upload)

xFormat's video converter changes MP4, MOV, MKV, WebM, AVI and FLV files entirely inside your browser, so your videos are never uploaded to any server.

Runs in your browser — files never leave your device.

How it works

Drop in a video, pick the format you need, and download the result. Everything runs on your own device, which means no upload queue, no file-size paywall and no watermark. It works in desktop browsers as well as on iPhone and Android.

1
Drop a video file onto the page, or tap to choose one.
2
Pick the target format: MP4, WebM, MOV, MKV, AVI or FLV.
3
Click Convert, then save the finished file.

Container swap first, re-encode only when needed

A video file is a container (MP4, MKV, MOV) wrapped around compressed video and audio streams. If the target container can hold the codecs already inside your file, the converter just repackages them. That is fast and loses no quality, because no frame is decoded or re-compressed. Before you click Convert, the tool tells you which of the two will happen.

When the codecs do not fit the target, for example VP9 video going into MP4, the file is re-encoded: H.264 video and AAC audio for MP4, VP9 and Opus for WebM (VP8 and Vorbis if compatibility mode has to do the job). Re-encoding takes longer and is slightly lossy, so it is worth choosing the target format with that in mind.

Which format should you choose?

MP4 is the safe default: it plays on phones, TVs, Windows, macOS and most editors. WebM is a good fit for embedding on websites. MKV is flexible and handy for archives, but fewer phones and TVs open it. AVI and FLV are legacy formats, mostly useful for old players or software.

Conversion uses your browser's built-in, hardware-accelerated media encoders where the device supports them. For formats the browser cannot decode, such as AVI, it switches to a compatibility mode. That mode downloads a roughly 31 MB engine the first time and then stays cached.

File size and device limits

Plan for files up to about 500 MB on a desktop browser and around 200 MB on a phone, because the browser has to hold the file in memory while it works. Larger files may fail or run out of memory.

Frequently asked questions

Is my video uploaded anywhere?

No. The conversion runs inside your browser tab, and the file is never sent to a server. You can even disconnect from the internet after the page has loaded, unless the compatibility engine still needs to be downloaded.

Will converting reduce video quality?

Not if only the container changes (for example MOV to MP4 with compatible codecs), since the streams are copied as they are. If the file has to be re-encoded, a small quality loss is normal.

Which formats can I convert between?

You can convert between MP4, WebM, MOV, MKV, AVI and FLV. Audio-only output, compression and trimming have their own tools on xFormat.

Can I convert videos on my iPhone or Android phone?

Yes, it works in mobile browsers. Keep files under roughly 200 MB on a phone, because mobile browsers have less memory to work with.

Is it really free? Is there a watermark?

It is free, needs no account and adds no watermark. There is no daily limit imposed by a server, because no server is involved.