HarmonyAngel is a MIDI and vocal harmony processor for musicians who want one monophonic line to follow the active chord. Choose chord slots on two performance pages, then play from a MIDI controller or the on-screen piano. For every incoming note, HarmonyAngel can generate descending chord tones below it, align voicings to a chord root, preserve slash-chord roots, and forward aftertouch to the generated harmony. Turn on Mic Input to sing into HarmonyAngel. The app performs low-latency monophonic pitch detection locally, uses the detected note to create chord-aware MIDI harmony, and provides a live tuner and input-level meter. Premium users can optionally hear pitch-corrected lead vocal and pitch-shifted vocal harmony audio, with selectable pitch detector, pitch shifter, formant, latency, buffer, trigger-level, and trigger-velocity controls. Use HarmonyAngel standalone with CoreMIDI and the built-in sine synth, or load the AUv3 MIDI processor inside a compatible host. Page controls, progression stepping, hold behavior, custom chord types, selectable MIDI ports, channel routing, keyboard range, display transpose, and velocity shaping are available from the performance UI. Highlights: - Two pages of 12 editable chord slots with no-harmony slots - Built-in chord types, slash roots, and named custom chord types - Full or partial on-screen piano with touch velocity and aftertouch - Mic Input with local monophonic vocal pitch detection, tuner, and input-level metering - Premium pitch-corrected lead vocal and pitch-shifted vocal harmony audio - Premium single-channel or rotating-channel harmony MIDI output - Premium AUv3 MIDI processor extension with preservable host state - Optional built-in sine wave synth for quick testing or standalone use HarmonyAngel is designed for keyboardists, singers, composers, producers, worship musicians, live performers, and anyone who wants fast chord-aware harmony from simple MIDI or vocal input. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://bwinnovationtw.github.io/apps/harmonyangel/privacy.html