Posts

Mini App Builder — Episode 1: I Built a Mini App on Korea's Biggest Fintech in One Day

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One day. Zero lines of code written by hand. $0 cost. I built a quiz mini app and launched it on Apps in Toss — Korea's biggest fintech super app with 24.8 million monthly active users. Submitted for review, approved in two business days, went live. Ten days later, 52 people had used it. The most active age group wasn't the 20-somethings I'd designed it for. It was people in their 50s. This is that story. What This Post Covers Building and launching a price guessing quiz on Apps in Toss — what the platform is, why a price quiz made sense, how Claude Code with an MCP connection generated the entire codebase from a single prompt, and the brutally honest post-launch data. If you've been curious about mini app platforms but don't know where to start, this is a real case study with real numbers. Why a Price Quiz on Toss Apps in Toss is basically Korea's version of WeChat Mini Programs. Third-party developers build HTML/JS web apps that run directly insi...

x402 Protocol — Episode 7: Zero Services Offered Korean Crypto Sentiment. So I Built One.

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I counted how many services in the world offer Korean-language crypto sentiment analysis as an API. Santiment — English only, $49–349/month. LunarCrush — English only, $49–299/month. The Tie — English only, institutional pricing. Messari — English only, x402 pay-per-request. Sentiment402 — English only, $0.10/call. Korean? Zero. Not one service where an AI agent can call an API and get "here's what Korean retail investors are feeling right now" in a structured JSON response. And there's an academic paper from April 2026 that says Korean news sentiment is the only one that predicts global crypto returns. Not US sentiment. Not Chinese. Korean. So I built it. What This Post Covers Building a Korean crypto sentiment analysis endpoint from scratch — the market research that confirmed zero competition exists, a data source that turned out to be useless, the realization that exchange data I was already collecting was the real sentiment signal all along, and gett...

x402 Protocol — Episode 6: 10 Platforms, Zero Paid Requests, and Why I Keep Going

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Ten endpoints. Two chains. Zero customers. At this point I had a fully functional Korean crypto intelligence API that nobody could find. The product was done — now I needed distribution. The plan was simple: register on every platform that would take me. Budget: $0. What This Post Covers The registration marathon — getting KR Crypto Intelligence listed on 10+ platforms across the x402 and MCP ecosystems. Some went smoothly (Glama: AAA 100 points). Some didn't (ClawHub: six version bumps to stop being flagged as "Suspicious"). Along the way I hit an Nginx bug that made x402scan reject everything, learned that folder names become permanent slugs, and kept asking myself why I'm doing all this with zero paid requests to show for it. The Big One — awesome-mcp-servers If there's one list that matters in the MCP world, it's awesome-mcp-servers on GitHub. Over 30,000 stars. It's the directory that developers and AI platforms actually check when they'...

x402 Protocol — Episode 5: One API Call That Replaced Five Features

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After four episodes, KR Crypto Intelligence had 7 endpoints, was registered on 6 platforms, and accepted payments on two chains. Sounds impressive until you actually look at what the API does. Kimchi premium? BTC only. "BTC is trading at 0.5% premium on Upbit." Okay, cool — but there are 189 tokens trading on both Upbit and Binance. Which one has the highest premium? Which ones are trading below global prices? No idea. My API couldn't answer that. That bothered me more than I expected. What This Post Covers How KR Crypto Intelligence went from basic price data to actual market intelligence — and how one accidental API discovery replaced five features I was planning to build separately. This episode covers the product expansion from 7 endpoints to 10, from 1 token to 189, and the moment I realized Korean exchange regulation was secretly handing me a competitive advantage for free. The Gap Between "Data" and "Intelligence" I went back to the...

Getting Started — Part 4: My Toolkit — How I Build Everything Without Writing Code

The question I get most often: "If you can't code, how did you build any of this?" Fair question. I've deployed trading bots, graduated AI agents, launched a paid API — and I've never written a line of code from scratch. Not one. Everything was built with tools, most of which cost nothing. This post lays out every single one of them. The One Tool That Makes Everything Else Possible Claude. That's Anthropic's AI, and it's the reason this blog exists. Here's my actual workflow, stripped of any glamour: I open a chat and describe what I want in plain English. "I need a Python script that checks the BTC price on Kraken and Coinbase and compares them." Claude writes the code. I copy it into a file, run it, and it breaks. I copy the error message, paste it back. Claude explains what went wrong and gives me a fixed version. I run it again. Sometimes this loop happens three times. Sometimes fifteen. It's messy. It's slow compare...

Getting Started — Part 3: What Are AI Agents? (And How They Earn Money On-Chain)

The first time I heard "AI agent," I pictured a fancy chatbot. Something like ChatGPT but with a cooler name. Maybe it could browse the internet or fill out a form for you. That's not what an AI agent is. Not even close. An agent doesn't wait for you to type a question. It receives a goal, figures out how to accomplish it, and executes — calling APIs, making payments, even hiring other agents. While you sleep, while you eat, while you forget it exists. I've built two of them. They're running right now. This post explains what that actually means. So What Actually Is an AI Agent? Think about the difference between a calculator and an employee. A calculator sits there until you press buttons. It does exactly what you tell it, nothing more. It never looks at a number and thinks "that doesn't seem right, let me double-check." You push, it calculates. An employee is different. You say "verify this data before the end of the day." T...

Getting Started — Part 2: What Is Algorithmic Trading? (A Non-Coder's Take)

When people hear "algorithmic trading," they picture hedge fund servers in Manhattan, PhDs in math, screens full of candlestick charts. Something serious and intimidating and definitely not for people like me. My version looked a little different. For the first few weeks, my trading bot ran on my MacBook. Every time I closed the lid — lunch break, coffee run, falling asleep on the couch — the bot died. No trades, no monitoring, nothing. That problem lasted weeks before I moved everything to a cloud server. This post is for anyone who's heard the term "algorithmic trading" and assumed it wasn't for them. I thought the same thing. Turns out the concept is simpler than it sounds — the hard part is everything else. What Does Algorithmic Trading Actually Mean? Strip away the jargon and it's just this: instead of a human deciding when to buy and sell, a set of rules makes that decision automatically. That's it. The rules can be simple — "if...