The Script That Taught Me RSI (and Didn't Make Me Rich)

It was 2020. We were all stuck inside. Some people baked sourdough. Some people learned to knit. I wrote a script to yell at me about a stock.

Here’s what I was actually after. I’d grown fond of an indicator called RSI — the Relative Strength Index, a number between 0 and 100 that tries to tell you whether a stock has been bought or sold so hard, so fast, that it’s due for a breather. Push above 70 and the crowd might be a little too excited (overbought). Drop below 30 and it might be a little too gloomy (oversold). Traders have squinted at those two lines for decades.

I wanted to catch the exact moment price crossed one. So I built a thing.

The script is simple. It logs into my account, grabs closing prices over and over, and hands them to a library called ta-lib to do the actual RSI math — because rolling your own technical-analysis formulas is a wonderful way to be confidently wrong. When the number pokes above my ceiling or below my floor, my Mac throws up a notification. Ping. “Hey. Look at this.”

And then… nothing dramatic happened.

I did not get rich. That was never really the deal.

What I got instead was an education. Building the alert taught me more about momentum indicators than any article ever did, because I had to make it real — pick a period, set the thresholds, watch it fire on live data and mutter “huh, that’s not what I expected.” You don’t actually understand a thing until you’ve had to argue with it in code.

Now, the obligatory part: this is not financial advice. It’s barely financial. It’s a hobby script that sends a desktop notification and lets a computer decide it’s time to pay attention. If you take trading tips from something I built between loaves of banana bread, that’s between you and your broker.

But if you genuinely want to learn how an indicator behaves — not read about it, learn it — build the smallest possible thing that puts it in front of your face. Set the floor. Set the ceiling. Watch it trip.

You’ll forget the article by Tuesday. You’ll never forget the code you had to fight. Mine’s at github.com/thatsjet/robinhood-rsi-alert if you want a head start on the fighting.