I Built an Open-Source Guitar Tuner That Runs Entirely in Your Browser (No Libraries, No Backend)
Most guitar tuners on the web are black boxes.
You don’t know how they work.
You can’t modify them.
And almost none of them are built with accessibility in mind.
So I built my own.
It’s called PitchCraft.
An open-source chromatic tuner that runs entirely in your browser using the Web Audio API.
No backend.
No tracking.
No external tuning libraries.
Just signal processing and math.

Live demo:
https://indjoov.github.io/pitchcraft/�
GitHub:
https://github.com/indjoov/pitchcraft�

The Moment That Triggered It
I’m a musician and developer.
One day I needed a simple tuner.

I opened a popular web tuner and thought:
Why does this feel like magic I can’t see inside?
So I asked myself:
What if I build one completely from scratch?
Not using a tuning library.
Not using a backend.
Just the browser.
That question became PitchCraft.
The Crazy Part: The Browser Is Enough
Modern browsers can do real-time pitch detection.
Here’s the pipeline:
Microphone → Frequency → Note → Visual Feedback
Using:
getUserMedia
AnalyserNode
autocorrelation
equal temperament math
That’s it.
No server needed.
The Core: Autocorrelation Pitch Detection
The tuner works by detecting periodicity in the waveform.
Simplified:
The algorithm compares the signal with delayed versions of itself.
When it matches, that delay equals the fundamental frequency.
From there:
Frequency → Note → Cents deviation
All in real time.
This is the same principle used in professional tuners.
I Also Wanted It to Be Accessible
This part matters a lot to me.
Most music tools ignore accessibility.
So PitchCraft includes:
high contrast mode
large text mode
reduced motion mode
full keyboard navigation
screen reader support
Because creative tools should be usable by everyone.

It Currently Supports
Guitar
Bass
Ukulele
Violin
Cello
Banjo
Mandolin
Chromatic mode
With adjustable reference

tuning:
432 Hz → 444 Hz
Built With
React
Vite
Web Audio API
pure JavaScript pitch detection
No external tuning libraries.
Everything runs locally.
The Hardest Part
Not the math.
Not React.
The hardest part was making it feel good.
Low latency.
Stable detection.
Clear feedback.
That took the most iteration.
Why I Open-Sourced It
Because I believe creative tools should be transparent.
You should be able to:
understand them
modify them
improve them
Not just consume them.
The Code Is Surprisingly Small
The entire tuner logic lives in one core component.
Signal processing in JavaScript is much more accessible than people think.
The browser is a powerful DSP environment.
Try It Yourself
Live:
https://indjoov.github.io/pitchcraft/�
Source:
https://github.com/indjoov/pitchcraft�
What I Learned Building This
Three things surprised me:

The Web Audio API is insanely powerful You can build real music tools in the browser.
Signal processing is not as scary as it seems Basic math gets you far.
Accessibility is not hard — but you must care Most tools simply don’t. Roadmap Next features I want to build: MIDI input strobe tuner mode drop tunings PWA offline mode I’d Love Feedback Especially from: musicians audio developers accessibility developers What would you improve? Why This Matters We’re entering a time where the browser is becoming a creative instrument. Not just a document viewer. PitchCraft is a small example of that shift.