Is this MP4 to AVI 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 MP4 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.

MP4 to AVI Converter — Free, Fast, In-Browser

How to convert MP4 to AVI online

1
Drop your MP4 file
Drag and drop your MPEG-4 Part 14 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 MPEG-4 Part 14 → Audio Video Interleave entirely in your browser tab using WebAssembly. Most files finish in 1–3 seconds.
3
Download your AVI
Your Audio Video Interleave file is ready. Click Download, or grab a ZIP if you converted a batch. Close the tab and everything disappears — no copies kept anywhere.

MP4 vs AVI: format overview

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
✗ H.264 has royalty implications

AVI

Audio Video Interleave

Microsoft · 1992

Compression: lossy
Transparency: No

✓ Universal Windows compatibility
✓ Simple container format — widely supported

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

AVI magic bytes: 52 49 46 46 xx xx xx xx 41 56 49 20

Why convert MP4 to AVI?

If you've ever tried to open a MP4 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.

MPEG-4 Part 14 is great for what it was designed for, but it has real-world limitations: h.264 has royalty implications and not ideal for video editing (better to edit in prores/dnxhd). The moment you step outside that original context, it gets frustrating fast.

Audio Video Interleave is the safer choice for Legacy Windows video, DVD ripping, Older camcorder output. Its main advantages — universal windows compatibility and simple container format — widely supported — 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 MP4 - They need a smaller file for email or upload (AVI often compresses better) - They need Audio Video Interleave's specific capability: universal windows compatibility - Compatibility with older software that pre-dates MPEG-4 Part 14

The conversion is one-way: you get a AVI that works everywhere Audio Video Interleave is expected. The original MP4 file is not touched.

Quality & file size: MP4 to AVI

Typical file sizes: MP4 100–300 MB → AVI 200–600 MB.

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

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

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

Frequently asked questions

Privacy: how FormatDrop handles your files

Your MP4files 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.