Built on Cloudflare
Where your AI work adds up
v2.2.0 · MIT
A year of using AI
should add up to
something
You think out loud with these tools now, and none of it stacks. Second Brain is where it does. Every tool and device you use reads from the same memory and adds to it, so there is nothing to sync between them, and it sits in an account that belongs to you.
You worked this out once, properly. Four months later you shouldn’t have to do it again from memory.
All that thinking, and you’re no further along
You think out loud with these tools now. Real decisions, real problems, hours of it. How you priced the work. Why you turned that project down. What you told the client, and what you decided not to say.
Every conversation is good, and then it’s gone. A month later you’re working the same thing out from scratch, and the second version is worse, because the first one had detail you have since forgotten.
The tools do remember some things now. But that memory is rented. It builds up inside one product, it only ever helps you inside that product, and it leaves when you do.
Second Brain is where it stacks. Every tool you use reads from it and adds to it, and it sits in your account, not ours.
It fills up on its own
Connect the places you already keep things and your brain starts with something in it. No blank page, no new habit to keep up, and nothing that leaves your account.
Obsidian
Years of notes you wrote and filed by hand, finally readable by your AI tools. You don’t change how you write.
Notion
The pages you already keep, without copying them anywhere new or maintaining a second version of them.
The threads where you actually said the thing. It skips the newsletters and the promos, and keeps the parts you’d want your AI to know.
Calendar
What you did and when you did it, so “back in March” turns into an actual week you can ask about.
All of it readable from Claude, ChatGPT or Cursor, and all of it sitting in an account that belongs to you.
It shows up in every tool you work in.
Work something out in ChatGPT and it’s there in Claude and Cursor too, not just where it came from. One address connects all of them.
It’s in your account, not ours
Second Brain runs inside your own Cloudflare account. Not a copy of your work on our servers, and not a plan you can be moved off. We can’t read any of it, because it was never ours to read.
Your own account
It deploys into Cloudflare under your login. The database, the search index and the AI all run in there, on the free tier.
Open source, MIT
The whole thing is readable. Fork it, audit it, change it, or run your own version and never speak to us again.
It outlasts us
Nothing here depends on us staying in business. That is rather the point of a place your thinking is meant to pile up.
Up and running in three steps
Download the app
Grab the desktop app for Mac or Windows. Cloudflare provisions your D1 database, Vectorize index, and Worker behind the scenes. Nothing to configure.
Connect your tools
Paste one address into Claude Desktop, Claude Code, claude.ai, Cursor, Windsurf or anything else you use. Same memory in all of them.
It starts stacking
It fills up as you work, and the parts that matter come back when they’re relevant. A month from now it’s still there. A year from now it’s worth something.
See it in action
The same question asked in ChatGPT, Claude and Cursor. Same answer in all three, because they’re reading from the same place.
Not just memory. Understanding that compounds.
Second Brain doesn’t just keep what you tell it. It answers from it, settles contradictions, and surfaces patterns you never wrote down.
AI Synthesis
Ask “what did I land on for pricing?” and get an answer built from what’s saved, not a wall of raw entries. The notes it drew on are listed underneath if you want them.
Pattern Derivation
Second Brain reads across your memories after every search and surfaces themes you never wrote down. “You revisit this tradeoff every quarter.” Worked out, not told.
Search by meaning
Ask about “conversion problems” and it finds the note where you wrote “users dropping off at checkout.” No exact wording, no tags to keep up.
Smart Merge
When two memories conflict or overlap, Second Brain settles it, merging near-duplicates and correcting contradictions. What you have stays clean over months.
Importance Scoring
Every memory gets an AI score when it’s saved, and the ones you keep coming back to rank higher over time. Ask “what was I building last Tuesday?” and get the right moment.
One brain, every tool
Claude, ChatGPT, Cursor, Windsurf and anything else that connects, all reading and writing the same memory. Set it up once.
Web Dashboard
Browse by date, filter by tag, edit memories in place. Export everything to JSON or Markdown. You can see everything it kept, and delete anything you don’t want.
Self-Hosted
Runs entirely in your own Cloudflare account. Nobody else touches your data. Free and open source, no credit card, no lock-in.
Your brain never contradicts itself.
Most memory tools accumulate. Second Brain reconciles. Every new memory is checked against what’s already stored, so conflicts get resolved, near-duplicates get merged, and stale beliefs get replaced.
“Based in New York, not planning to move anytime soon.”
“Moving to Lisbon in March. Remote made it possible, cost of living did the rest.”
“Moving to Lisbon in March. Remote made it possible, cost of living did the rest.”
Contradiction Detection
Every incoming memory is compared by meaning against the ones already there. When two beliefs conflict, Second Brain flags it and settles on the newer one, without you having to manage it.
Smart Merge
Near-duplicates in the 0.85–0.95 similarity band go through an LLM prompt that decides: keep both, replace, or merge into a single coherent memory. Nothing accumulates blindly.
Hard Duplicate Block
Exact or near-exact matches (≥0.95 similarity) are blocked before storing, with no LLM call and no overhead. Your brain stays dense, not bloated.
A full UI at your Worker URL.
No separate service. No extra deploy. Open your Worker URL in any browser. Auth is handled client-side and your token lives in localStorage.
Recall
Search by meaning across your whole brain, not keyword matching. “payment drop-off” finds “users abandoning checkout”. Each result shows match score, tags, source, and timestamp.
Recent
Every entry in reverse chronological order. Filter by tag to review what you stored under work or decision this week. Append updates or forget entries inline.
Remember
Type a note and hit save. Drop #tags anywhere in the text and the UI strips them out and stores them as tags. Works from your phone browser too.
Extend your Second Brain
Save anything, from anywhere. Wherever the thought happens.
Second Brain CLI
Save and search from your terminal. Pipe meeting notes, grep output or anything else straight into your brain, no copy-paste required.
Obsidian Plugin
Make your vault readable by your AI tools without changing how you write. Send everything or just the notes you tag, kept up to date as you save, with a sidebar for searching your brain without leaving the app.
iOS Shortcuts
Save a thought the moment it lands. A voice memo while walking, a quick text note, or straight from any app’s share sheet.
Second Brain vs. the alternatives
The popular memory tools each ask for a trade-off: your data on their cloud, a usage meter, or one machine only. Second Brain doesn’t.
Built entirely on Cloudflare’s free tier
Free and open source, and personal use sits inside Cloudflare’s free tier. No credit card. Schema creates itself. You own every byte.
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