Is this AAC to FLAC 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 right in your browser. 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 converter engine 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 AAC 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.

What bitrate will the converted audio use?

We default to 192 kbps for MP3, 128 kbps for OGG/Opus, and 320 kbps for M4A/AAC. These settings are perceptually transparent — most listeners can't tell the difference in a blind test.

Will my metadata (ID3 tags, album art) be preserved?

Yes, when both formats support it. Tags carry over on conversions like MP3→M4A or FLAC→MP3. WAV has limited tag support, so some metadata may not transfer.

Will converting AAC to FLAC make the audio lossless?

No — FLAC stores what's in the AAC source without further loss, but cannot restore detail the AAC encoder discarded. The output is a lossless container of a lossy source — useful for compatibility, not for quality improvement.

Why would my hi-fi DAC or music player need FLAC instead of AAC?

Many audiophile DACs, network streamers (Naim, Cambridge, Bluesound), and music servers (Roon, JRiver) have limited codec support and only read FLAC/WAV for local playback. Converting AAC to FLAC enables these devices to play the files.

How private is this converter?

Completely private — by design, not policy. There is no upload endpoint. Files are processed right 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.

AAC to FLAC Converter — Free, Online, No Upload

How to convert AAC to FLAC online

1
Drop your AAC file
Drag and drop your Advanced Audio Coding 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 Advanced Audio Coding → Free Lossless Audio Codec entirely in your browser tab. Most files finish in 1–3 seconds.
3
Download your FLAC
Your Free Lossless Audio Codec file is ready. Click Download, or grab a ZIP if you converted a batch. Close the tab and everything disappears — no copies kept anywhere.

AAC vs FLAC: format overview

AAC

Advanced Audio Coding

Dolby, Fraunhofer, Sony, Nokia · 1997

Compression: lossy
Transparency: No

✓ Successor to MP3 — better quality at same bitrate
✓ Native support across Apple, Android, YouTube
✗ Not fully royalty-free

FLAC

Free Lossless Audio Codec

Josh Coalson / Xiph.Org · 2001

Compression: lossless
Transparency: No

✓ Lossless compression — identical to source
✓ 50–60% smaller than WAV with no quality loss

AAC magic bytes: FF F1 (ADTS) / 00 00 00 xx 66 74 79 70

FLAC magic bytes: 66 4C 61 43

Why convert AAC to FLAC?

AAC is a widely distributed format — Apple Music, iTunes purchases, YouTube audio, and many podcast feeds deliver audio in AAC. The problem is that the hardware and software designed for serious listening often speaks only FLAC. Audiophile DACs from brands like Chord, iFi, and Schiit, network streamers from Naim, Cambridge, and Bluesound, and music server software like Roon and JRiver Media Center are built around lossless formats (FLAC and WAV) and frequently won't mount or play an AAC or M4A file at all.

Converting AAC to FLAC is the compatibility bridge that makes those files readable on lossless-first hardware. The FLAC stores the decoded AAC audio without any further encoding — no additional quality loss beyond what the original AAC compression already introduced. The format switch unlocks playback on hi-fi equipment that would otherwise reject the file entirely. FLAC also handles metadata far more reliably in audiophile software than AAC's MP4 container tags.

It's important to be clear about what doesn't happen: the conversion does not make the audio lossless. FLAC is a lossless codec wrapping a lossy source. Listeners won't hear quality improvement over the AAC original — they'll hear the same audio, now accessible on hardware that previously couldn't play it. If true lossless audio is the goal, the original recording must be sourced from a lossless master, not re-encoded from AAC.

Quality & file size: AAC to FLAC

Typical file sizes: AAC 2–5 MB → FLAC 20–40 MB.

Converting from lossy AAC to lossless FLAC will not recover detail the AAC codec already discarded — but the output will not degrade any further. This is useful when you need a lossless format for editing or compatibility without additional compression artifacts.

Color depth: AAC supports standard color, FLAC supports standard color.

Transparency: AAC does not support transparency. FLAC does not support transparency — transparent areas become solid white.

Frequently asked questions

Privacy: how FormatDrop handles your files

Your AACfiles are converted 100% inside your browser. 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.