Guido Jacofsky · Buenos Aires I build software that touches the physical world.

• before$ 400.000 / yr

  now$ 25.500 / yr

  OftalmoLegal

  2026 · Live

  My dad's website: a WordPress landing page that cost ARS 400,000 a year and didn't show up on Google. I rebuilt it as a static site, with an interactive perimeter and full SEO and GEO. Now only the domain costs money: 94% less.

  Astro · TypeScript · SEO / GEO

  oftalmolegal.ar ↗Read the note →
• RepoGuide

  2026 · v1.0 live

  Understand any repository in 20 minutes. It analyzes a GitHub repo and tells you what to read, what to skip and in what order for the task at hand, and it remembers what you already understood.

  Next.js · Prisma · Postgres · Groq · Auth.js

  repoguide-six.vercel.app ↗Read the note →
• codeAB01

  salerecorded

  stock−1

  Sanitarios Moldes

  2026 · First version

  My grandfather's plumbing supply shop is 50 years old and never had a system. I built the online catalog with in-store pickup and a counter that looks items up by code, records the sale and updates stock, so he can check how the day is going without being there.

  Next.js · Prisma · SQLite · shadcn/ui

  Read the note →
• Bot P2P USDC/ARS

  2026 · Done

  Compares the price of USDC in pesos between p2p.me and Binance P2P and pings Telegram when the gap goes over 1%. It reads prices straight from the smart contract on the Base network, with no browser or login.

  Python · asyncio · Base / EVM · Telegram API

  Read the note →
• 08:00

  13:00

  20:00

  PetCare

  2025 · School ICT project

  A smart pet feeder with an ESP32-CAM: schedules, portions, treats and a camera from an app. I built the backend (Node, Express and PostgreSQL) and the portion recommendation by breed and weight.

  Node.js · Express · PostgreSQL · ESP32

  github.com/guidojacoo/petcare ↗Read the note →
• • MaySana · Di Tella
  • JunGemm Blocks · ITBA
  • 2026TICApp

  Hackathons

  2026 · Three, and a class

  Sana, at Di Tella: AI triage for places with no doctor nearby, designed and pitched in two hours. TICApp, an AI platform for teachers: we didn't win. And one Google ran at ORT, where we showed Gemm Blocks; that led to a class at ITBA.

  Next.js · Bun · Supabase · LLMs

  Sana →TICApp →Gemm Blocks →

My first trade was at 11. Then came stocks, futures and different ways of reading a market, and over the years one question stuck: why does the same thing cost different amounts in different places? Today I do arbitrage between pesos, dollars, euros and crypto, and I run the numbers in Excel.

1. Age 11

   A Binance account

   A family member helped me get started by opening a Binance account for me to use. Even at that age I was curious about crypto, and especially about one idea: buying something at one price and selling it later for more.

   Trying out strategies I found on YouTube and combining indicators, I bought Solana at 22 USDT. Two years later I sold it at 200 USDT. The figure isn't the point. It was the first time I bought and sold something and it worked, and it left me wanting to understand more.

2. After that

   Learning on my own

   I kept going on my own, with YouTube channels and whatever material I could find. I went through crypto, stocks and futures, and picked up different ways of trading and of analyzing a market.

   There was no plan. I moved from one market to the next, trying to understand how prices move, what pushes them and how each instrument works.

3. Over the years

   The gap, not the direction

   At some point I stopped asking only whether something would go up or down. I got interested in how markets work underneath, and especially in something that keeps happening: the same thing isn't worth the same everywhere. The price of an asset or a currency changes between exchanges, between currencies and between P2P platforms, where people buy and sell directly with each other.

   That's what arbitrage is: finding those gaps and working out whether they're worth taking. It doesn't depend on guessing where the price is headed. It depends on getting the math right.

4. Now · age 17

   Multicurrency arbitrage

   Today it's something I actively do. I work with Argentine pesos, US dollars, euros, crypto and stablecoins, on exchanges and in P2P markets. I compare prices and exchange rates, think through the possible conversion routes and work out what each step costs.

   A gap on a screen isn't a profit. Between what you see and what you keep there are fees, the cost of each conversion and whatever it takes for the trade to actually go through. A gap that looks good can leave nothing, or a lot less than it seemed.

   Currencies

   Argentine pesos (ARS) · US dollars (USD) · Euros (EUR)

   Crypto

   Cryptocurrencies and stablecoins

   Where

   Exchanges and P2P markets

   Math

   Excel spreadsheets with formulas

5. How

   The math, in Excel

   Over time I built a way of working that I repeat on every operation. It runs on Excel spreadsheets with formulas: the prices, the cost of each step and what's left at the end. That way I decide with the math done, not by eye or in my head.

   It's the same way I think when I code: understand how the system works, separate what something looks like from what's actually happening, and let the decision come out of a process I can repeat.

   fx=C2-D2

   	A	B	C	D	E
   1	buy at	sell at	gap	costs	left
   2	price	price	=B2-A2	=SUM(steps)	=C2-D2

It started with a kid's question: if I buy at this price, can I sell it for more? Six years later my questions aren't that different, but I answer them differently: with formulas, with costs, and looking at several markets at once.

• 01

  From idea to deploy, on my own

  I design, build, ship and maintain complete products: Quicky, Platto, RepoGuide, my grandfather's shop system.

  See →

• 02

  Software that moves hardware

  I build the virtual reality teleoperation and the panel for a humanoid robot. What I code gets tested on a real robot, not just on a screen.

  See →

• 03

  Finding the real failure

  When something works only sometimes, I measure before changing things. That's how I found what killed the Parque de la Innovación demo.

  See →

• 04

  Designing without a designer

  I think up the interfaces and build them myself. Platto, RepoGuide and this site were designed that way.

• 05

  Talking to customers and industry

  I prepared and ran meetings with YPF and Pan American Energy, presented Gemm at the Parque de la Innovación and taught a class at ITBA.

  See →

• 06

  Coding with Claude Code

  I know how to use Claude Code to move fast without losing control: I understand what it generates and can fix it when it breaks.

Languages

TypeScriptJavaScriptPythonSQLCBash

Web

Next.jsReactTailwind CSSNode.jsBunExpressElysiaFastAPIREST APIsWebSocketsAuthshadcn/ui3D and AR in the browser

Data

PostgreSQLPrismaDrizzleSupabaseNeonRedisSQLite

Robotics

VR teleoperationUnitree G1 and Go2ROS 2Embedded LinuxWebRTCMuJoCoESP32

AI

Claude CodeLLM APIsComputer vision3D reconstructionPandas / NumPyMachine learningSpeech (STT / TTS)

Deploy and tools

Git / GitHubVercelDockerTurborepoGitHub ActionsRailwayPlaywrightFigma

Languages

Spanish (native) · English (advanced, C1)

• Oct 3G1 teleop with arms and high-definition video in the headset: everything worked, four days after the demo failed on stage.
• OctoberCalibrating the panel's stuck-teleop detector with real sessions, and waiting for the Dex5-1 hands to test manipulation on the robot.
• PlattoIn development. While I validate the product I upload the 3D models by hand; the scan automation is ready but switched off.
• Until DecFinishing my last year at ORT.
• 2027University as the frame, a startup as the goal.

Updated: October 3, 2026

Featured

• 01

  Build before planning

  A working MVP beats a perfect plan. Action produces information.

• 02

  Problem first

  Gemm taught me this: interesting technology doesn't mean anyone needs it. That's why we went to talk to YPF and PAE before building more.

• 03

  Speed with understanding

  I code with AI, but if I don't understand what it generated I can't fix it when it breaks. And it always breaks at the worst moment.

• 04

  Only claim what's validated

  If something works in simulation, I say simulation. If a provider isn't connected, the system says so instead of making up a result.