Is this FLAC to OPUS 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 FLAC 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.

Is 96 kbps Opus really as good as lossless FLAC?

In double-blind listening tests, Opus at 96 kbps is perceptually transparent for most music content — listeners cannot reliably distinguish it from the lossless source. At 128 kbps, it's considered indistinguishable by essentially all listeners.

What apps and services support Opus playback?

Opus is supported by all major browsers, VLC, MPV, Discord, Telegram, WhatsApp, Android, and most modern streaming stacks. It is not natively supported by iTunes or Apple Music.

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.

FLAC to Opus Converter — Free, Online, No Upload

How to convert FLAC to OPUS online

1
Drop your FLAC file
Drag and drop your Free Lossless Audio Codec 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 Free Lossless Audio Codec → Opus Interactive Audio Codec entirely in your browser tab. Most files finish in 1–3 seconds.
3
Download your OPUS
Your Opus Interactive 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.

FLAC vs OPUS: format overview

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
✗ Not supported on iOS/iTunes natively

OPUS

Opus Interactive Audio Codec

IETF / Xiph.Org · 2012

Compression: lossy
Transparency: No

✓ Best low-bitrate quality of any audio codec
✓ Royalty-free and open standard (RFC 6716)

FLAC magic bytes: 66 4C 61 43

OPUS magic bytes: 4F 67 67 53 (Ogg container)

Why convert FLAC to OPUS?

FLAC is the right format for an archive — lossless, metadata-rich, universally accepted by audiophile software. But for anything that moves audio over a network, FLAC's file sizes are a serious liability. A FLAC track might be 25–40 MB; the same content in Opus at 96 kbps sounds identically good and fits in under 2 MB. For web audio, self-hosted podcast streaming, WebRTC applications, and browser-based audio delivery, that difference in size directly translates to faster load times and lower bandwidth costs.

Opus is the codec used by Discord, Zoom, WhatsApp, Google Meet, and Spotify's internal streaming layer. All major browsers support it natively in HTML5 audio elements. Developers building web applications that serve audio — music players, podcast apps, interactive audio experiences — increasingly choose Opus for its combination of quality and efficiency. At 96 kbps, Opus is perceptually transparent for music; at 32–48 kbps, voice content sounds excellent. Starting from FLAC ensures the encode is first-generation with no prior lossy artifacts.

The resulting Opus file will be 90–95% smaller than the FLAC source, with no audible difference at 96 kbps or above. Opus is not supported by iTunes or Apple Music, so this conversion is suited to web delivery and streaming contexts rather than Apple device playback. For Apple compatibility, FLAC to M4A is the better route.

Quality & file size: FLAC to OPUS

Typical file sizes: FLAC 20–40 MB → OPUS 1–3 MB.

Converting from lossless FLAC to lossy OPUS will apply compression. We default to 85% quality — visually indistinguishable from the original for most content. If you need pixel-perfect output, consider using a lossless target format instead.

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

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

Frequently asked questions

Privacy: how FormatDrop handles your files

Your FLACfiles 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.