Why does the first WMV conversion take longer?

WMV is not a format browsers can decode on their own, so the first time you convert one, a compatibility engine of about 32 MB downloads. After that it is cached, and every later conversion, including offline, skips the wait.

Will the quality drop?

Converting re-encodes the video, but with the Balanced or Best preset the change is hard to notice. Old WMV files are often low resolution to begin with, so the MP4 will look about the same while playing on far more devices.

Can it handle other old formats too?

Yes. The same compatibility engine reads ASF, AVI, FLV, MPEG, VOB and other legacy formats, so if you have a folder of mixed old video, most of it will convert to MP4 here.

Is my file really not uploaded?

No. Your file is read and converted on your own device and never sent anywhere. You can prove it: convert one WMV while online (which downloads the compatibility engine once, about 32 MB), then switch to airplane mode and convert another. It still works, because everything needed is now on your machine.

NoUpload | Convert WMV to MP4, Private and Free

Turn old Windows WMV video into MP4 that plays on phones, Macs and the web, without uploading your file to anyone.

WMV is Microsoft's Windows Media format. For years it was what Windows Movie Maker exported and what old camcorders and screen recorders produced, so a lot of people have WMV files sitting in an archive. The trouble is that almost nothing outside Windows plays them cleanly: Macs, iPhones, Android and most websites either refuse a WMV or need an extra plugin. Converting WMV to MP4 makes those old clips playable again, everywhere.

It all runs inside your browser: your video is converted on your device and never reaches a server, which is worth caring about for old personal footage and family videos. In March 2025 the FBI's Denver office warned it was increasingly seeing criminals use free online file converters to spread malware, including ransomware, so converting locally sidesteps that risk.

WMV is one of the formats browser video engines cannot read directly, so this uses a built-in compatibility engine, a full video decoder compiled to WebAssembly, to handle it. That engine downloads once, then works offline for every conversion after. You can shrink the result with a quality preset or a lower resolution if the MP4 needs to be smaller.

How to convert WMV to MP4

Drop your WMV file onto the box above, or click to choose it. Your file stays on your device.
MP4 is already selected. Optionally pick a quality preset or a smaller resolution to reduce the file size.
Click Convert, then download your MP4. The first WMV conversion downloads the compatibility engine, so it takes a moment longer; later ones are quicker.

Why convert WMV to MP4 here

Your file is never uploaded. There is no server to upload it to.
Reads WMV and other legacy formats (ASF, AVI, FLV, MPEG) that browsers cannot play directly.
No account, no email, no watermark and no daily limit.
Works offline once the compatibility engine has downloaded once.

Frequently asked questions

Why does the first WMV conversion take longer?: WMV is not a format browsers can decode on their own, so the first time you convert one, a compatibility engine of about 32 MB downloads. After that it is cached, and every later conversion, including offline, skips the wait.
Will the quality drop?: Converting re-encodes the video, but with the Balanced or Best preset the change is hard to notice. Old WMV files are often low resolution to begin with, so the MP4 will look about the same while playing on far more devices.
Can it handle other old formats too?: Yes. The same compatibility engine reads ASF, AVI, FLV, MPEG, VOB and other legacy formats, so if you have a folder of mixed old video, most of it will convert to MP4 here.
Is my file really not uploaded?: No. Your file is read and converted on your own device and never sent anywhere. You can prove it: convert one WMV while online (which downloads the compatibility engine once, about 32 MB), then switch to airplane mode and convert another. It still works, because everything needed is now on your machine.

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