chords·lol vs OtoTheory

chords·lol is a free browser platform for learning and referencing chords, scales, keys, progressions, and music theory. Its index contains 360 chords across 30 qualities and twelve roots, with notes, intervals, keys, and playable diagrams for guitar, piano, ukulele, bass, mandolin, and banjo. The learning library lists 107 scales, 30 keys, 30 progressions, and 26 theory guides. Nine browser tools include chord and scale finders, a transposer, ear training, a progression generator, and a metronome. The site provides 19 printable PDF charts covering chords, scales, and keys. Tools require no account or signup; the maker says there are no email gates or paywalls. Chord and scale data, audio, and PDFs may be downloaded for personal, classroom, and non-commercial use. Privacy information describes anonymous Vercel Analytics and PostHog usage data, Do Not Track support, no data sales, and no third-party advertising scripts. Terms provide no warranty of accuracy or fitness for a particular purpose.

OtoTheory is a chord progression builder and music theory companion for guitar, bass, and keyboard players, songwriters, and DAW users. Its iOS app can identify chords, key, and song sections from imported audio or an on-device guitar or piano recording. Users can paste progressions from ChatGPT, Claude, or Gemini for Roman numeral analysis and playback with grooves. The app lists 19 groove patterns and more than 50 progression presets; OtoTheory AI suggests chords using musical feel, theory, and emotion. Pro exports MIDI in Groove, Groove + Theory, or Chords Only modes, including BPM, section markers, and chord names. The maker says those exports can be used with Logic Pro, Cubase, Ableton, and other DAWs. OtoTheory is available on iOS and the web, but the web version has fewer features and Pro is iOS-only. The free iOS plan allows three local sketch saves and excludes MIDI and audio export. Pro is listed from $5.99/mo; its annual plan is $49.99/year, and Lifetime costs $99.99 once.