Is this WEBM to MP4 converter really free?

Yes. Up to 5 files at a time, no signup, no catch. The free tier adds a small watermark to image output — Pro ($9.99/mo or $49/yr) removes it, raises the file size limit to 500 MB, and unlocks unlimited batch conversion.

Are my files uploaded to a server?

No — and you can verify it yourself. Open DevTools → Network tab, then convert a file. You'll see zero upload requests. Everything runs in your browser via WebAssembly. We never see your files.

How long does conversion take?

Usually 1–3 seconds for a typical file. The very first conversion on a fresh page load may take 5–20 seconds while the WebAssembly codec loads — after that it's instant. Your CPU does all the work locally.

What is the file size limit?

Free: up to 10 MB per file, 5 files per batch. Pro: up to 500 MB per file, unlimited batch. If you're working with large videos or RAW photos, Pro is built for that.

Can I batch convert multiple WEBM files at once?

Yes — drop multiple files at once (or Ctrl/Cmd+click to select them) and they all convert in parallel. Free accounts handle up to 5 files per batch; Pro has no limit.

How large can my video files be?

Free accounts support files up to 10 MB — enough for short clips and GIFs. Pro raises that to 500 MB, which covers most 1080p videos. For files over 1 GB, a native app like HandBrake will be faster.

Will the video lose quality during conversion?

When only the container changes (e.g., MKV → MP4 where both use H.264), there's zero quality loss — it's a lossless rewrap. When the codec changes, we encode at CRF 23, which is near-transparent for most content.

How private is this converter?

Completely private — by design, not policy. There is no upload endpoint. Files are processed using WebAssembly inside your browser tab and disappear the moment you close it. We collect only anonymous page-view counts; your file content is never seen or stored.

Convert WEBM to MP4 Online — Free & No Signup

How to convert WEBM to MP4 online

1
Drop your WEBM file
Drag and drop your WebM Video Format file onto the converter, or click to browse your files. You can select up to 5 at once. Nothing leaves your device — conversion happens right here in the browser.
2
Hit Convert — it happens locally
Click Convert and watch it go. There's no upload, no server queue, no waiting. The converter runs WebM Video Format → MPEG-4 Part 14 entirely in your browser tab using WebAssembly. Most files finish in 1–3 seconds.
3
Download your MP4
Your MPEG-4 Part 14 file is ready. Click Download, or grab a ZIP if you converted a batch. Close the tab and everything disappears — no copies kept anywhere.

WEBM vs MP4: format overview

WEBM

WebM Video Format

Google (On2 Technologies) · 2010

Compression: lossy
Transparency: No

✓ Royalty-free codec (VP8/VP9/AV1)
✓ Excellent web streaming support
✗ Not supported on iOS/Safari natively

MP4

MPEG-4 Part 14

Moving Picture Experts Group · 2001

Compression: lossy
Transparency: No

✓ Universal compatibility across all platforms
✓ Excellent compression with H.264/H.265

WEBM magic bytes: 1A 45 DF A3

MP4 magic bytes: 00 00 00 xx 66 74 79 70

Why convert WEBM to MP4?

If you've ever tried to open a WEBM file and hit a wall — the app won't accept it, the website rejects it, or the preview just shows a broken icon — you already know why this conversion matters.

WebM Video Format is great for what it was designed for, but it has real-world limitations: not supported on ios/safari natively and not accepted by most social media platforms. The moment you step outside that original context, it gets frustrating fast.

MPEG-4 Part 14 is the safer choice for Web video, Social media uploads, Video streaming. Its main advantages — universal compatibility across all platforms and excellent compression with h.264/h.265 — mean it just works wherever you need it.

A few common reasons people end up here: - Their target app, site, or device doesn't accept WEBM - They need a smaller file for email or upload (MP4 often compresses better) - They need MPEG-4 Part 14's specific capability: universal compatibility across all platforms - Compatibility with older software that pre-dates WebM Video Format

The conversion is one-way: you get a MP4 that works everywhere MPEG-4 Part 14 is expected. The original WEBM file is not touched.

Quality & file size: WEBM to MP4

Typical file sizes: WEBM 50–200 MB → MP4 100–300 MB.

Both WEBM and MP4 use lossy compression. We transcode at high quality settings (equivalent to MP4's recommended web quality) to minimize generational loss.

Color depth: WEBM supports standard color, MP4 supports standard color.

Transparency: WEBM does not support transparency. MP4 does not support transparency — transparent areas become solid white.

Frequently asked questions

Privacy: how FormatDrop handles your files

Your WEBMfiles are converted 100% inside your browser using WebAssembly. They are never uploaded to our servers, never stored, and never seen by anyone other than you. This isn't a privacy policy claim — it's an architectural guarantee: our server has no endpoint that receives file bytes.