I Built a DJ Playlist Optimizer Without Writing a Single Line of Code Myself

BrAInStorm — Sun, 01 Mar 2026 22:20:56 +0000

I'm not a programmer. I run a YouTube channel about electronic music (634K subs) and I DJ psytrance.
I built a web app that solves a real problem I kept running into. Here's what happened.

The Problem

Every DJ using Rekordbox (in my case) knows this: you can sort playlists by key OR by BPM, but not both.
And the key sort is alphabetical - A, Ab, Am, B — which has nothing to do with harmonic compatibility. Pioneer's own forum has a feature request for this sitting there for years.
With 20 tracks, there are 2.4 quintillion possible orderings. No one's doing that by hand.

What I Built

HarmonySet — upload your Rekordbox playlist (.txt), get the mathematically optimal track order for harmonic mixing and energy flow (Serato and Traktor coming soon).
The algorithm:

Calculates harmonic distance between every track pair using the circle of fifths
Solves it as a Traveling Salesman Problem (Held-Karp DP for ≤20 tracks, greedy + 2-opt for larger)
Three energy modes: Ramp Up, Ramp Down, Wave Runs client-side — files never leave your browser

The Stack

Next.js 16, TypeScript, Tailwind
Supabase for auth and saved playlists
Vercel for hosting
Monthly cost: $0

How It Got Built (Without Me Coding)

I used Claude Code as my development tool. Not autocomplete — the actual developer. I described what I wanted, reviewed output, tested, iterated.
Phase 1: Python prototype on Streamlit. Ugly. Proved the algorithm worked.
Phase 2: Full rewrite in TypeScript/Next.js. Proper UI, accounts, freemium tiers.
Phase 3: SEO. The site was live for a month and completely invisible to Google — no robots.txt, no sitemap, the 404 page was injecting noindex on every unmatched URL. Fixed all of it in one session.

Numbers

99 tests passing (didn't write any of them)
Optimization runs in under 1 second
0 files sent to any server
512 Google impressions in the first week of indexing
~7,300 words of guide content for DJs
Running cost: $0/month

Mistakes I Made

Fell into the vibe coding aesthetic trap. My first version looked like every other AI-generated landing page — purple gradients, radial glows, generic SaaS template energy. I didn't realize how much that was killing credibility until I saw a viral post about how "vibe coding floods the web with purple AI sites." DJs would take one look and bounce. I had to scrap the design and rebuild it to look like an actual pro-audio tool, not an AI demo. Lesson: if your site looks like AI made it, your target users won't trust it — especially in a niche like DJ software where aesthetics signal legitimacy.

Underestimated parsing. The algorithm was maybe 20% of the work. Making the tool handle every weird Rekordbox export format — UTF-16LE encoding, tab delimiters, five different key notation systems — that's where most of the debugging went.
Started with the wrong tool for the job. The first version was a basic Python script I built with Gemini. It worked, but out of curiosity, I brought it to Claude Code to see if it could improve the algorithm. It rebuilt the whole thing from scratch in TypeScript — better architecture, better optimization, proper test coverage. And the differences were dramatic.

What I Learned

AI tools don't replace understanding. I can't write TypeScript, but I know the architecture. When something broke, I described the problem accurately because I understood what the code was supposed to do.
Domain expertise is your moat. I knew harmonic mixing was a real pain point because I live it. That same expertise told me the purple gradient design was wrong — no real DJ tool looks like that. You can't prompt your way into either insight.
A non-programmer can ship a real product in 2026. Not a toy. 99 tests, structured data, SEO, auth, database. The bar for "you need to be a developer" has moved.

Try It

harmonyset.com — upload a playlist, see what happens. If you use Rekordbox specifically, there's a step-by-step guide for exporting and optimizing.
Code is on GitHub.
Two things I'd like feedback on:

If you're a DJ, do the energy modes feel right for your sets?
If you're a builder using AI tools, what is it that you found that needs to improve?

A website I created using Manus AI

BrAInStorm — Fri, 23 Jan 2026 21:34:52 +0000

Hi. I am the owner and curator of a large YouTube channel focused on electronic music. While I do have hundreds of thousands of subscribers, all the activity takes place only on the YouTube platform. I thought to myself, what can I do to get more exposure, and then I thought, why not try a website.

I went to Manus, and after describing the idea and vision, it created this for me. What is great here is that I have options that I don't have on YouTube. Like, for example, a complete portal of the main artists on the channel. A radio option. I consider creating a community too.

It is a site that can also function as a PWA, and it does work well on my iPhone. This is just an initial model that I am also going to connect to the domain I purchased, but Manus is an amazing tool that I am not sure gets the credit and awareness it deserves.

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