# zelva

> Independent software studio (sole proprietorship) by Masashi Yamada (山田 雅史), based in Tokyo, Japan. Develops simple, high-quality, browser-based tools — primarily for musicians and audio software developers — guided by the philosophy of "unadorned, unhindered: forms that never stop your thinking."

The site is bilingual. Default URLs serve Japanese; English equivalents live under `/en/*`.

Content licensing: search indexing and AI grounding / retrieval-augmented generation are welcomed. Bulk collection for AI model training is reserved (see `/robots.txt`).

## Products

- [notave](https://zelva.dev/notave): Browser-based guitar TAB & standard-notation editor. Generates Drop 2 / Drop 3 voicings from chord symbols, plays back, prints, and exports MP4 video (16:9 / 9:16 / 1:1). Free tier + Pro subscription (¥450/mo JP, $2.99/mo elsewhere). Live app at https://notave.zelva.dev
- [ARA Sleuth](https://zelva.dev/ara-sleuth): Free, open-source (MIT) VST3 debugging tool for ARA2 plugin developers. Visualizes ARA host behavior differences across DAWs (Studio One, Reaper, Cubase). Source: https://github.com/masa-x/ara-sleuth

## Free music tools

All run entirely in the browser, no sign-up.

- [Chord Beat Sequencer](https://zelva.dev/tools/chord-beat-sequencer): Combined chord (up to 128 steps) + 16-step × 6-track drum + auto-bass sequencer. Share loops by URL, export as Standard MIDI File.
- [Chord Chart](https://zelva.dev/tools/chord-chart): Guitar chord diagram lookup (major / minor / 7th / extensions). Audio playback, favorites, print. Per-root pages at `/tools/chord-chart/{root}`.
- [Scale Chart](https://zelva.dev/tools/scale-chart): Guitar scale position diagrams (CAGED, pentatonic, blues, modes). Per-root pages at `/tools/scale-chart/{root}`.
- [Circle of Fifths](https://zelva.dev/tools/circle-of-fifths): Interactive circle with diatonic chords, related keys, modal interchange, secondary dominants, and a progression player.
- [Metronome](https://zelva.dev/tools/metronome): Adjustable tempo, time signature, tap tempo.

## Blog (music theory articles, ja + en)

- [Blog index](https://zelva.dev/blog)
- [Drop 2 Voicing Guide](https://zelva.dev/blog/drop2-voicing-guide)
- [Drop 3 Voicing Guide](https://zelva.dev/blog/drop3-voicing-guide)
- [Chord Tone Omission](https://zelva.dev/blog/chord-tone-omission)
- [Slash Chord Guide](https://zelva.dev/blog/slash-chord-guide)
- [Secondary Dominant Guide](https://zelva.dev/blog/secondary-dominant-guide)
- [Tritone Substitution Guide](https://zelva.dev/blog/tritone-substitution-guide)
- [Reharmonization Guide](https://zelva.dev/blog/reharmonization-guide)
- [Diatonic Chord Guide](https://zelva.dev/blog/diatonic-chord-guide)
- [Circle of Fifths Guide](https://zelva.dev/blog/circle-of-fifths-guide)
- [Altered Scale Guide](https://zelva.dev/blog/altered-scale-guide)
- [Progression-Scale Guide](https://zelva.dev/blog/progression-scale-guide)
- [Related ii-m7 Guide](https://zelva.dev/blog/related-iim7-guide)
- [Beginner Chord Guide](https://zelva.dev/blog/beginner-chord-guide)
- [Chord Chart Guide](https://zelva.dev/blog/chord-chart-guide)
- [Scale Chart Guide](https://zelva.dev/blog/scale-chart-guide)
- [Metronome Guide](https://zelva.dev/blog/metronome-guide)

## Company

- [About / Legal Notice](https://zelva.dev/about): Sole-proprietorship details (Specified Commercial Transactions Act disclosure), address, contact.
- [Contact](https://zelva.dev/contact)
- [Privacy Policy](https://zelva.dev/privacy)
- [News](https://zelva.dev/news)
- [Sitemap](https://zelva.dev/sitemap.xml)