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Sonic Visualiser vs Spek: catalog facts
Sonic Visualiser	Spek
Free Free and open source. Hosting, hardware and any external services are separate.	Free Free and open source under GPLv3.
Windows, macOS, Linux	Windows, macOS, Linux
Supports layered audio visualizations Works with analysis plug-ins	Shows instantly whether a lossless-looking file was upconverted from a lossy source Uses FFmpeg for decoding, so it opens the formats FFmpeg opens
Designed for analysis rather than multi-track music production.	Development is quiet: the last release, 0.8.5, is from January 2023 It only views spectrograms; it cannot edit or convert anything
Downloadable app	Downloadable app
Open source	Open source
License not stated	License: GPL-3.0
Not stated if an account is needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 20, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.