About

I'm a solo developer who builds AI-powered web apps, content automation tools, and financial education products from the ground up — then ships them publicly. My stack is Rails 8 + Hotwire on the backend, Flutter for mobile, and whatever AI API does the job: GPT-4o, DART API integrations, or custom pipelines I wire together on a VPS I run myself.

I don't work inside teams. I scope, design, build, deploy, and market solo. In the past 12 months I shipped 35+ deployed projects: a gamified financial literacy SaaS with a native mobile app, a real-time AI stock analyzer for Korean retail investors, an AI carousel generator for solo creators, and viral image analysis apps. Every step — the technical decisions, the failures, the revenue experiments — goes on my Substack (@solovibecoder), my TikTok (@thecashlingo), and my YouTube channels. I build in public so you can follow along or steal whatever works.

Projects

Five flagship products — solo apps and AI integrations I've shipped recently.

2025

Jumptest preview
FEATURED

Jumptest

I built Jumptest because Korean retail investors had no AI tool for reading DART financial filings in plain language. The hard part was streaming GPT-4o responses over ActionCable in real time while simultaneously keeping a Turbo Native iOS and Android shell in sync — all running on my own VPS, zero managed infrastructure. Now it's live at jumpriq.com with real users running stock queries.

  • Rails 8.1
  • Stimulus
  • ActionCable
  • GPT-4o
  • DART API
  • Turbo Native

2026

CashLingo preview
FEATURED

CashLingo

I built CashLingo because solopreneurs in Korea lacked a gamified, mobile-first way to learn personal finance — everything that existed was either dry textbooks or paid courses. The hard part was keeping a Rails backend fully in sync with a Flutter mobile client across quizzes, hearts, streaks, and league mechanics — plus adding i18n so the same content works in Korean and English. Now it's live at cashlingo.org as a full-stack SaaS with a native mobile app on both platforms.

  • Rails 8.1
  • Hotwire
  • Flutter
  • SQLite
  • i18n

2026

CarouselMaker preview
FEATURED

CarouselMaker

I built CarouselMaker because creating an Instagram carousel manually takes 30+ minutes per post — design, copy, layout, export. I needed something I could prompt once and get a publish-ready slide deck. The hard part was maintaining visual consistency across AI-generated slides: font sizing, color hierarchy, and line breaks behave unpredictably when you hand off to a model. Now it's live at carouselmaker.cashlingo.org as a Korean-language SaaS and I use it for my own content every week.

  • Rails 8.1
  • Hotwire
  • Tailwind CSS
  • AI content generation

2025

CringeProphet preview
FEATURED

CringeProphet

I built CringeProphet because AI image analysis demos are always boring — upload a face, get a JSON blob back. I wanted to make it shareable: upload a photo, pick an era, and the AI predicts the most embarrassing things that would have happened to you back then. The hard part was generating responses that were genuinely funny and slightly roast-y without tipping into mean — the model needed careful prompt engineering and Solid Queue to handle async image processing without blocking requests. Now it's live at thecringeoracle.jumpriq.com and people share the results.

  • Rails 8.1
  • Hotwire
  • Solid Queue
  • AI image analysis

2025

SoloVibeCoder Newsletter preview
FEATURED

SoloVibeCoder Newsletter

I built the SoloVibeCoder newsletter platform because I needed to dogfood my own publishing stack — if I'm going to write about shipping products, I should ship the thing I write on. The hard part was running EN/KO simultaneous publishing with AI-assisted translation while keeping the Tiptap block editor feeling like a real writing tool, not a dev experiment. Now it's live at solovibecoder.jumpriq.com and powers the newsletter I publish alongside my main Substack at solovibecoder.substack.com.

  • Rails 8.1
  • Hotwire
  • ESBuild
  • Tiptap
  • AI i18n
View all 35 projects

Get in Touch

Available for solo product collaborations, AI integration consulting, and selective client work. Reach me at [email protected].

Designed & built solo by Jennie Su · 2026

Loosely inspired by brittanychiang.com