Pontifork
Ponticello’s tuner, for every string
Pontifork tunes the cello, the guitar with six or seven strings and the bass with four, five or six — in every standard, drop, open and lowered tuning players actually use, with a chord book that follows your tuning. Open it in any browser or install the app. No account, and nothing leaves your device.
The mark
Pontifork is ponticello — Italian for “little bridge” — and a tuning fork. The mark is the fork in the bridge’s bleached maple, with the bridge’s round heart cut through its knob, ringing out four waves in the colours of the four strings: C green, G red, D blue, A yellow, left to right. On iOS the fork and the waves are separate Liquid Glass layers, drawn in Icon Composer the same way as Ponticello’s.
One engine, three instruments
Cello, guitar and bass
Pontifork listens with Ponticello’s dual-rate engine, built for an instrument whose lowest note the body barely radiates — and widened to reach a five-string bass in drop A at 27.5 Hz and a guitar’s twelfth fret. It judges octaves by the period, not the loudest harmonic, so a low string is never read an octave up and a high one never an octave down.
Measured against the string
A chromatic tuner says what note you are playing. Pontifork says how far the string is from where your tuning wants it. Switch to drop D and pluck the low E: it reads D2 · hearing E2 · +200¢ · tune down, not “E, in tune”.
Every tuning players use
Half and whole step down, C♯ to B standard, every drop from D to A — and to F♯ on seven strings — double drop D, open D, E, G, A and C, DADGAD, QOTSA’s GGDGDD on guitar and bass, bass tenor and high C, and the cello’s scordaturas for Bach and Kodály. Each one shows its open strings before you pick it.
Lock a string
Pontifork follows whichever string you play. When a string is so far off that its neighbour is nearer — dropping a seven-string from B to A, say — tap it, and the tuner stays on that string however far away it starts. Tap it again to go back to following.
Reference pitch
A = 440 Hz is concert pitch, but orchestras often sit at 442, and baroque ensembles at 415. Move the reference a hertz at a time, from 415 to 466, and every string moves with it. It is remembered, along with your instrument and tuning.
The chord book
Twelve roots of ten types (major, minor, 7, m7, maj7, sus2, sus4, 5, dim and aug) for cello, guitar and bass, worked out for the tuning and capo in use.
Shapes follow the tuning
The book lists chords by how they sound. Tune half a step down and B’s page shows the C shape you already know, and says so; a whole step down that shape is B♭, and with a capo on the second fret it is D. Drop tunings keep the shapes and fret the low string two higher, or leave it out. Open tunings, DADGAD, QOTSA and the cello’s scordaturas get shapes of their own, found by search.
On guitar each chord has its open shape, where it has one, and the E and A shape barres; a seven-string adds the E shape on its low string. Bass and cello chords are found the same way as Ponticello’s, within one hand’s reach.
Keys
Pick a key and its own page opens: in G major, G, Am, Bm, C, D, Em and F♯dim with their numerals, then the sevenths. Every other page lists the key’s chords first and fades the rest. Minor keys include the major V nearly every song in a minor key uses.
Sequences
Tap + on a chord and it joins the sequence pinned under the book. Keep as many as you like, name them, move and remove chords. Play shows each chord in turn, two seconds apiece, without a sound, so the music is yours. A sequence remembers the tuning it was made in, and offers to switch back to it.
How to use it
The same on a phone, a tablet or a computer.
Open the tuner in a browser — or the app — and allow the microphone when asked. On the web, press Enable microphone first: a browser only listens after you ask it to.
Cello, guitar or bass, and for guitar and bass how many strings it has. Pontifork remembers the choice.
Press Change on the tuning card. Tunings are grouped — standard and lowered, drop, open, alternate — each with the notes of its open strings.
Pluck or bow one open string and let it ring. The big letter is the note that string should be; the needle and the number show how far off it is, in cents.
Tune up means flat: tighten. Tune down means sharp: loosen. Small turns, then let the string ring again.
Hold a string in the green for a moment and it gets a tick. Tightening one string changes the pull on the others, so go round them all once more.
Reading the dial
The dial spans half a semitone either way; beyond that the needle waits at the edge and the number keeps counting.
The catalogue
Generated from the app’s own catalogue, and checked against it by the test suite.
Standard and lowered
Scordatura
Standard and lowered
Drop
Open
Alternate
Standard and lowered
Drop
Alternate
Standard and lowered
Drop
Alternate
Standard and lowered
Drop
Alternate
Standard and lowered
Drop
Alternate
On any device
The web app is the same app — the same engine, the same tunings — on a phone, a tablet or a computer. Add it to your home screen and it opens full screen, like the native one.
Promises
Free and open source
Pontifork is built with Expo and React Native for iOS, Android and the web, from Ponticello’s pitch engine. The core — the engine, the string targeting and the tuning catalogue — is pure TypeScript, tested against every open string of every tuning. Add a tuning in one line and the tests check it keeps the promise in its name.
git clone https://github.com/GMBermeo/pontifork
cd pontifork
npm install
npm run web # the tuner in your browser
npm run ios # or on a phone
npm run verify # types, lint, tests