Crafting Kai: The Synth Keyboard Born from Vibe Coding

Hey there, fellow creators! Today I want to take you on a journey through the creation of Kai, my web-based synthesizer keyboard.

This project wasn’t just about writing code — it was about vibe coding: letting the rhythm of creativity guide me, blending music, design, and tech into something that feels alive. Let’s dive into how Kai came to be, the tools I used, the challenges I faced, and why vibe coding might just be the secret sauce to your next passion project.

What’s Vibe Coding, Anyway?

Before we get into the nitty-gritty, let’s define vibe coding. It’s not a formal term (yet!), but for me, it’s about coding with a flow state—where the process feels less like a checklist and more like jamming with a musical instrument. It’s about chasing a feeling: the thrill of hearing a synth note play for the first time, the satisfaction of a sleek UI coming together, or the joy of solving a bug while sipping coffee to a lo-fi beat. Kai was born from this mindset — less about perfection, more about expression.

The Spark of Kai

The idea for Kai hit me one lazy afternoon in early 2025. I’d been tinkering with JavaScript and audio APIs, inspired by the idea of bringing music creation to the browser. I wanted something simple yet powerful—a synth keyboard where anyone could play notes, tweak sounds, and record their vibes, all without downloading a thing. With Next.js 15.2.4 and Tone.js as my tools, I set out to build it, not knowing it would turn into a rollercoaster of creativity and problem-solving.

The Tech Stack

• Next.js 15.2.4: The framework that powered the app’s structure and deployment to Vercel.

• Tone.js: A fantastic library for handling audio synthesis and analysis, making the synth engine a breeze.

• Tailwind CSS: For that smooth, responsive UI with a futuristic vibe.

• Vercel: My go-to for hosting, with built-in analytics to track how people use Kai.

• A Dash of TypeScript: To keep the code clean and catch errors early.

Building the Vibe, Step by Step

1. Laying the Foundation

I started with the keyboard layout—mapping keys like A, W, S to notes like C4, C#4, D4. The initial code felt clunky, but as I played with Tone.js’s PolySynth, the first note rang out, and I was hooked. That moment of hearing sound in the browser? Pure vibe coding fuel. I added a waveform visualizer using the Web Audio API’s AnalyserNode, turning raw audio data into a mesmerizing bar graph.

2. Designing the Feel

The UI was all about intuition. I used Tailwind to craft buttons for oscillator types (sine, square, sawtooth, triangle) and recording controls, with subtle shadows and transitions to make it feel tactile. The Kai logo (a custom SVG) became the centerpiece, grounding the design. Vibe coding here meant tweaking colors and layouts until it felt right — less about pixel-perfect specs, more about the emotional resonance.

3. Adding Features

Recording was a breakthrough. Using MediaRecorder to capture the synth output into a WAV file felt like unlocking a new instrument. Playback and download features followed, with a custom analyser to visualize recorded audio. Each feature was a jam session—test, tweak, listen, repeat. The process was messy but exhilarating, driven by the desire to share this with others.

4. The Deployment Dance

Deploying to Vercel was a challenge. My first build failed due to TypeScript and ESLint errors (e.g., unused useRef imports, missing useEffect dependencies). With help from sharp AI assistants (thanks, Grok and Cline on VS Code!), I debugged the SynthKeyboard.tsx file, fixed type issues, and added Vercel Analytics to track usage. The final push was a victory lap.

Challenges and Lessons

Vibe coding isn’t all smooth sailing. I hit snags like audio context initialization (requiring user interaction) and inconsistent waveform rendering. The key? Embracing the flow, stepping back, experimenting, and leaning on community tools like Stack Overflow and AI-driven code reviews. I learned to trust the process: when the vibe feels off, take a break, play some music, and come back refreshed.

Why Kai is Vibe Coding in Action

Kai isn’t just a tech demo — it’s a testament to vibe coding. The project evolved organically, driven by curiosity and the joy of creation. Features like real-time waveform visualization and keyboard interactivity weren’t planned from day one; they emerged as I played with the code. The result? A synth that’s fun to use, with a soul that reflects my creative journey.

Try It Yourself!

Kai is live! If you prefer, access it on mobile and tap to install it as a PWA application (😁). Hit the keys, tweak the oscillators, record your vibe, and download it. I’ve enabled Vercel Analytics to see how people interact with it — maybe you’ll inspire the next feature! If you’re new to coding, start small: build a button that plays a sound, then let the vibe take over. That's the vibe!