Built a Chrome sidebar for ChatGPT/Claude/Gemini after getting frustrated losing context in long AI conversations
For the past 2years I kept running into the same problem, I'd be deep in a long ChatGPT or Claude conversation, want to ask a follow-up about something from 20 messages back, and end up losing the whole thread context by opening a new tab.
So I built SubSync. It's a Chrome extension that injects a resizable sidebar into ChatGPT, Claude ai, and Gemini. You select any text in the conversation, hit Sync, and ask your question in the sidebar. The extension scrapes the conversation context automatically so it actually knows what you're talking about.
A few things I ended up building along the way that weren't in the original plan:
- Notes mode inside the same sidebar create, pin, search notes and export them as .md files
- 24-hour chat history with session switching so you don't lose conversations
- API routing that detects your provider from the key prefix and calls them directly — falls back to a shared backend if you don't have a key set
- Conversation memory compression for long histories so it doesn't hit token limits
The hardest part was the conversation scraper. ChatGPT, Claude, and Gemini all have completely different DOM structures so I had to write separate extraction logic for each platform.
It's live on the Chrome Web Store.
Happy to answer any questions about how the context scraping works or the provider routing logic.