Convert any video to MP4 — right in your browser

MOV, MKV, AVI, WebM, and practically anything else with frames — OpenConvertVideo converts them all to MP4 right in your browser. Common formats can use your device's built-in encoder, so it usually finishes before you can wander off for coffee. No account, no size limit, and your files never touch a remote server.

Drop a file here, or click to choose

Converts right here — nothing uploads

Need trim, resize, or quality controls? Open the full converter →
  • No upload wait
  • Nothing leaves your device
  • Free, no account
  • No artificial size limits

H.264, H.265, or VP9 — which should I choose?

MP4 with H.264 is the safest choice when you have no idea what hardware the recipient is running. Hardware decoders for H.264 have been standard in phones, laptops, and TVs for well over a decade, which is why it plays natively on Windows, macOS, iOS, Android, every browser, and every smart TV — no extra apps required.

  • H.264 MP4 — maximum compatibility. Use for sharing, WhatsApp, Discord, email, and anything where you're unsure of the recipient's setup.
  • H.265 MP4 — same quality at roughly half the file size. Native on all Apple devices and modern Android. Windows needs the free HEVC Video Extension. Use for storage, archiving, or sharing with people on Apple devices.
  • VP9 WebM — open-format, excellent for embedding on websites. Plays in Chrome, Firefox, and Edge natively. Smaller than H.264 at the same quality.

Supported input formats

Any video format your browser can decode, including:

  • MOV — QuickTime files from iPhone, iPad, and Mac
  • MKV — Matroska, common for high-quality downloads and Blu-ray rips
  • AVI — older Windows format with DivX, Xvid, or MJPEG video
  • WebM — open-format web video
  • WMV, FLV, M4V, 3GP — legacy and mobile formats

Quality and resize options

Three quality presets: High preserves maximum quality (best for archiving or further editing), Balanced cuts file size by 50–70% with barely perceptible loss (recommended for most uses), and Small applies maximum compression for slow connections or email attachments.

Resize to 1080p, 720p, or 480p with aspect ratio locked automatically, or enter a custom width. Trim to a specific segment before converting using the Trim control.

How it works

OpenConvertVideo runs ffmpeg — the open-source engine that quietly powers a huge share of the internet's video tools — compiled to WebAssembly directly in your browser. We only supply that code; the actual encoding work is done entirely by your own device's processor. For common source formats (MP4, MOV, MKV, WebM), your browser's built-in encoder handles it, which is usually fast; rarer formats use the built-in software engine instead. Your file is read from disk, processed locally, and saved to your downloads folder. Nothing is ever sent to a server — which is why everything stays 100% private, as it should.

Frequently asked questions

Is the conversion fast?
Often yes. Common formats — MP4, MOV, MKV, WebM — can use your browser's built-in encoder, which is usually fast. Rarer formats like AVI or legacy codecs fall back to a software engine and take longer. Either way, there's no upload wait added on top, since nothing ever leaves your device.
Which quality preset should I use?
Balanced is right for most uses: sharing, uploading, watching. Use High if you plan to edit the output further or want to archive at near-original quality. Use Small when file size matters more than quality — email attachments, slow connections.
How much smaller will the output be?
Depends on the source. AVI files often shrink by 60–90%. iPhone MOV files (already efficiently compressed in HEVC) may only shrink 10–30% at Balanced. Reducing resolution has the biggest impact: dropping from 4K to 1080p cuts size by 70–80% before any quality setting.
Is there a file size limit?
No server-imposed limit — nothing is uploaded. The practical limit is your device's RAM. Most devices can handle files up to several gigabytes without issues.
Does it add a watermark to the video?
No. The MP4 you download is clean — no watermark, no branding, no time limit on the clip, and nothing locked behind a signup or a paid tier. The converter is free and supported by ads on the site, so your video stays exactly that: yours.
Can I resize the video while converting?
Yes. Choose from 1080p, 720p, or 480p, or enter a custom width. Aspect ratio is locked by default.

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