Spectro is a macOS application that detects fake lossless audio by analysing each file's actual frequency spectrum and returning a LOSSLESS, MEDIUM or FAKE verdict per track, rather than trusting the file extension.
What is Spectro?
Spectro is a local audio-quality checker for macOS that verifies whether a file is genuinely lossless. It takes individual tracks or entire folders in WAV, AIFF, FLAC, ALAC, MP3, AAC, Ogg Vorbis or Opus, runs a full FFT over the waveform, and outputs one verdict per file along with the measured cutoff frequency and a one-line diagnosis. It requires macOS 13 or later and ships as a universal binary for Apple Silicon (M1–M4) and Intel Macs. No individual developer is named on the page; the app is sold directly through getspectro.app with checkout handled by Lemon Squeezy.
What makes Spectro stand out?
- Spectral verdict engine — Every file gets one of three labels (LOSSLESS, MEDIUM, FAKE) based on spectral content, with the cutoff frequency reported, for example 15.9 kHz on a 128 kbps MP3 wrapped in FLAC versus 22.3 kHz on a genuine WAV.
- Peer-reviewed methodology — The analysis follows D'Alessandro & Shi (2009), MP3 Bit Rate Quality Detection through Frequency Spectrum Analysis (ACM Multimedia & Security), which reported 99% accuracy across 2,512 songs; the single ambiguous case, 256 kbps CBR versus high-quality VBR, is reported at 92.4% and explicitly flagged as MEDIUM.
- Batch scanning and bulk PNG export — Point Spectro at a folder, get a verdict per track, and export spectrogram PNGs for multiple results in one batch.
- Finder color tags — Spectro writes macOS Finder colour tags directly to the files, so a folder shows the problem tracks already marked without the app being open.
- Watch folders — A folder can be monitored so newly added tracks are analysed automatically.
- DJ library import — Rekordbox XML import via File → Import from Rekordbox, plus M3U/M3U8 playlist import; Traktor and VirtualDJ are listed as compatible, with Serato support marked coming soon.
- CSV export — File → Export CSV writes verdict, format, bitrate, cutoff frequency and confidence score for every track in a batch.
- Fully offline and account-free — Audio never leaves the Mac, there is no cloud upload, no library telemetry and no sign-up; the app is sandboxed and notarised and works with the network cable pulled.
Who should use Spectro?
- DJs maintaining a Rekordbox, Traktor or VirtualDJ library: audit a pool of downloads for MP3s renamed as WAV or AIFF before a set, and tag the offenders in Finder.
- Collectors with very large lossless libraries: batch-scan tens of thousands of files and export a CSV of cutoff frequencies and confidence scores; one quoted user ran a 653-track library and another cited a roughly 20TB FLAC collection.
- Buyers of Bandcamp, Beatport and promo-channel downloads: confirm that a purchased "lossless" master actually contains energy up to the Nyquist ceiling before trusting it.
- Anyone replacing bad files: filter the FAKE results, open the spectrogram for a second look, then move the confirmed fakes to Trash.
What can you do with Spectro?
- Pre-gig quality control: run a whole DJ pool folder through the scanner and get a LOSSLESS, MEDIUM or FAKE verdict per track before building a set.
- Rekordbox prep: import a Rekordbox XML export, check the collection, then export a CSV or review Finder tags before USB export.
- Purchase verification: inspect the spectrogram of a suspicious FLAC or WAV and see whether content stops at an MP3 brick wall or reaches the Nyquist ceiling.
- Ongoing library hygiene: leave a watch folder running so newly downloaded tracks are analysed on arrival.
How does Spectro work?
There is no import or setup step: files are dropped onto the app and analysed in place. Results stream in as each file finishes, and the user can then filter fakes, move them to Trash, or open the spectrogram before deciding to replace a track.
- Drop files or folders — FLAC, WAV, AIFF, ALAC, MP3, AAC, Ogg Vorbis, Opus, up to an entire ~/Music directory.
- Read the verdict per file, based on spectral content rather than the extension.
- Filter the FAKE results, move them to Trash, or open the spectrogram for a closer look.
Pricing
Spectro uses a one-time purchase model with a free trial. The trial covers the first 100 tracks with no time limit and no account or card required. The Personal licence costs $24.99 once for one Mac and Duo costs $39 once for two Macs; both plans include the same features, unlimited scans, free updates and a 30-day money-back guarantee, with no subscription or per-track fee. Licences arrive by email as a key entered in the app.
Alternatives
- Fakin' the Funk — a macOS fake-lossless detector referenced in a user comment on the Spectro page.
- Spek — a spectrum analyser for audio files; Spectro publishes a comparison guide positioning itself as a batch-oriented alternative with per-file verdicts and Finder tags.
FAQ
What is fake lossless audio?
A fake lossless file is an MP3 or AAC that has been re-encoded and saved as WAV, AIFF or FLAC. The file size grows but the audio is identical to the compressed original, and the high frequencies above the MP3 cutoff are permanently gone.
Does Spectro upload my files anywhere?
No. Analysis runs entirely on the Mac with no upload, no account and no telemetry, and no internet connection is needed. Payment is handled by Lemon Squeezy, so card details never reach the app's maker.
What are the free trial's limits?
Spectro is free for the first 100 tracks, with no time limit and no account or card required. After that, unlimited scanning requires a Personal licence for one Mac or a Duo licence for two Macs.
Does Spectro support ALAC and Ogg Vorbis?
Yes. Version 1.3 added full ALAC support, and Apple Lossless .m4a files are analysed the same way as WAV and FLAC. Ogg Vorbis and Opus are also supported, alongside MP3 and AAC.
Which Macs does it run on?
Spectro requires macOS 13 or later and is a universal binary covering Apple Silicon M1 through M4 and Intel Macs. It is sandboxed and notarised, and updates are delivered through Sparkle.
