Accordo

A free, ad-free, precision guitar & bass tuner that runs entirely in your browser.

Accordo is a lightweight Progressive Web App (PWA) built for beginners and pros alike: tune any 6/7/8-string guitar or 4/5/6-string bass with chromatic precision, pick from 50+ tunings, or tune by ear with built-in reference tones.

🎸 Try it live: accordo.tools — no install, no account, no ads.

Features

• 🎯 Accurate pitch detection — YIN algorithm with parabolic interpolation, accurate to well under 1 cent, from B0 (~23 Hz, 8-string flat tunings) up to the highest frets
• 🎸 Guitar & bass — 6/7/8-string guitars, 4/5/6-string basses
• 🎼 50+ tunings — every widely used tuning: Standards (E to F#), Drops (D to D on 8-string), Opens (G, A, C, D, D minor, E), DADGAD, All Fourths, high-C bass and more
• ✏️ Custom tunings — create, edit and save your own tunings with a visual note/octave editor, then share them as compact codes or one-tap links (accordo.tools/#…) that import and select the tuning automatically — all stored in your browser, no database needed
• 🔍 Smart search — relevance-ranked search that understands note names (standard e won't match Standard Eb)
• ♭ Flat switch — instantly shift any tuning down a half step
• 🔊 Sound mode — play realistic reference tones and tune by ear (works even without microphone access)
• 🤖 Auto string detection — the tuner recognizes which string you're playing
• ✅ Guided tuning — strings are validated one by one, with haptic feedback and a completion toast
• 🎚 Calibration — adjustable reference pitch (415–465 Hz, default A4 = 440 Hz)
• 🌍 9 languages — English, Français, Español, Italiano, Deutsch, Português, 中文, 日本語, 한국어 (auto-detected)
• 📱 PWA — installable on your home screen, works fully offline
• 🚫 No ads, no cookies, no tracking — audio is processed 100% locally; nothing ever leaves your device

Tech

• Pure vanilla JavaScript, HTML and CSS — zero dependencies, no build step
• Web Audio API (getUserMedia + AnalyserNode) for capture, YIN autocorrelation for pitch detection
• Additive synthesis (6 harmonics with exponential decay) for plucked-string reference tones
• Service worker for offline support
• Preferences and custom tunings stored in localStorage only — sharing works through self-describing codes in the URL fragment (no backend)

Run locally

No toolchain required — it's static files:

git clone https://github.com/Immolare/accordo.git
cd accordo
# serve with any static server, e.g.:
python -m http.server 8000
# then open http://localhost:8000

Microphone access requires a secure context: localhost or HTTPS (GitHub Pages works out of the box).

Deploy on GitHub Pages

1. Push this repository to GitHub
2. Settings → Pages → Source: deploy from branch main, folder / (root)
3. Settings → Pages → Custom domain: enter accordo.tools (the CNAME file in this repo keeps it set), point your DNS to GitHub Pages (A records or CNAME), and tick Enforce HTTPS
4. The tuner is live at https://accordo.tools

Security

• Strict Content Security Policy (self-hosted assets only, no third-party scripts)
• No external dependencies — nothing to supply-chain-attack
• Served over HTTPS with no referrer leakage (no-referrer policy)
• No cookies, no storage of personal data

Privacy

Accordo collects no data whatsoever:

• No cookies, no analytics, no trackers
• Microphone audio is analyzed in real time inside your browser and never recorded or transmitted
• Settings (tuning, language, calibration) are kept in your browser's local storage only

See the in-app legal notice for full details (French & English).

Author

Pierre Viéville — pierrevieville.fr

• 📧 contact@pierrevieville.fr
• 📸 Instagram: pierre.vieville.metal
• 🎵 TikTok: pierrevieville

License

Released under the MIT License — © 2026 Pierre Viéville.