Video Converter

Converting video without uploading it

A video is the most revealing file most people own, and handing one to a conversion service means trusting a retention policy you cannot inspect. The cases where that matters are not hypothetical: footage of your children, a recording of a medical consultation, an internal briefing that has not been announced, unedited material under embargo, a doorbell clip that might end up with an insurer. Most people do not think about it until the upload bar appears and it is too late to change their mind.

This page never shows that bar, because there is nothing to upload. FFmpeg, compiled to WebAssembly, runs inside your own browser tab on your own processor. The file is read from your disk by the page in front of you and never becomes part of a network request. There is no queue either, because there is no server taking turns between users.

What it can and cannot convert

The engine is FFmpeg, so the common ground is well covered: MP4, WebM, MOV, MKV and AVI on the video side, MP3, WAV, M4A and OGG on the audio side. If you have a clip from a phone, a camera, a screen recorder or a download, it will almost certainly be in that set.

Where it stops is worth knowing up front. Professional and broadcast codecs, DRM-protected files and anything with several audio tracks or embedded subtitles are outside what this page targets: the conversion writes a single video and a single audio stream, so extra tracks are not carried through. For those, desktop FFmpeg gives you control this page deliberately does not expose.

Speed, memory and the first run

The first conversion downloads the engine: one WebAssembly file of 32,129,114 bytes, about 30 MB, served from this domain rather than a CDN so that no third party observes that you are converting anything. It is never fetched on page load, only when you actually convert, and your browser caches it afterwards. On mobile data that first download is the slowest part of the whole operation.

After that the limit is memory rather than time. Everything is decoded inside the browser tab, so a long or high resolution video can exhaust what that tab is allowed and fail. No threshold is quoted here because there is no fixed one: it depends on your device, your browser and what else is open. Short clips and ordinary phone recordings are comfortable almost anywhere; 4K footage and anything approaching feature length is where a laptop succeeds and a phone gives up. If it fails on both, the file is genuinely too large for this approach and desktop FFmpeg is the honest answer.

Is my video uploaded anywhere?

No. The conversion engine runs on your device, so your file never leaves your browser.

Why is the first conversion slow?

The first run downloads the conversion engine, about 30 MB. After that it is cached. Large videos also take time because your device does the work.

What formats can I convert between?

The engine is FFmpeg, so it handles the common containers and codecs: MP4, WebM, MOV, MKV and AVI for video, and MP3, WAV, M4A and OGG for audio. Exotic professional codecs are the exception rather than the rule.

How large a video can this handle?

There is no policy limit, only your device's memory. Short clips and ordinary phone recordings are fine almost anywhere. Long recordings and 4K footage are where a laptop succeeds and a phone often does not. No specific size is quoted, because the real limit depends on your device and what else is open.

Why is a browser slower than a desktop converter?

A browser runs the encoder in a sandbox without access to the hardware video acceleration a native application can use. That is the cost of not uploading anything. For a short clip the difference rarely matters; for an hour of footage it does.

Does the conversion keep subtitles or several audio tracks?

Not reliably. The conversion targets a single video and audio stream, so extra tracks and embedded subtitles are generally not carried through. For anything with several tracks, desktop FFmpeg gives you the control this page does not.