How I built an AI spell-checker Chrome extension (and the API bill mistake that nearly killed it)

I kept sending messages with typos.

Not in documents — those have spell-checkers. I mean the places where you actually write all day now: the ChatGPT prompt box, a Gmail reply, a Messenger chat, a reply to a guest on Airbnb. Browsers underline the odd word, but they don't understand context, and they don't work consistently across every web app. So I built a Chrome extension to fix it, and called it TypoGuard.

It's an AI-powered spell and grammar checker that corrects your text in real time, inside the web tools you already use. Here's how it's built, and the one mistake that almost sank the whole thing.

The idea: Google's "Did you mean?" everywhere

Google Search has trained us all: you mistype, and it quietly suggests the right thing. I wanted that same experience in every text field on the web — Gmail, ChatGPT, Claude, Gemini, Messenger, Google Messages, and platforms like Airbnb and Booking where a clean message matters.