Your notes should outlive your subscription

The question I ask before trusting any app with my thinking

If I cancel tomorrow, what do I still have? Not what can I export, in some format I have to wrestle with, after digging through three settings screens. What do I still have, sitting on my machine, opening in any app I feel like using. For most AI memory the honest answer is nothing. The assistant remembers you right up until it does not, and when the plan lapses or the model changes underneath you, that memory is gone. You could never read it in the first place, so you cannot even tell what you lost.

Built-in memory is one locked copy per vendor

The memory inside ChatGPT or Claude belongs to ChatGPT or Claude. It is one copy per vendor. You cannot open it, you cannot move it, you cannot see what it decided to keep about you, and you cannot tell one assistant what the other one learned last Tuesday. Switch models and you start from zero. Cancel and it is over. That is not a bug in those products, it is what they are. Their memory is a feature of their subscription, not a thing you own. I go through the differences in detail in the comparison with ChatGPT memory.

So I built the other kind

Callosium points at a folder of Markdown files on your disk. Markdown just means plain text documents, the kind that open in Notepad, TextEdit, Obsidian, or anything else you already have. Nothing is uploaded to a service to make search work. The searching, the recall, all of it happens on your own machine. If you delete Callosium tomorrow, the folder is still there, every note still readable, nothing to export because nothing was ever taken away. That is the whole design, and everything else follows from it. If you want the practical version, here is how to build the folder itself.

The part almost nobody gets right: the paid plan

Free and local is easy. Plenty of tools do it. Here is where I found the real gap, and it is the one claim I care most about: your ownership survives the paid plan.

Callosium will have a paid tier with sync, so your notes follow you between devices. That sync runs through your own Google Drive, GitHub, or OneDrive. Your account, your storage, your rules. Your notes never sit on Callosium's servers at any price. Every other product I checked keeps its free tier local and then moves your live copy onto its own cloud the moment you start paying. You buy convenience and you pay in ownership, and it happens quietly, on the day you decide to trust them more.

I did not want to take my own word for this. A second set of agents went through the white paper adversarially, trying to knock down every claim that said only Callosium does this. Some claims fell and I cut them. This one survived.

What ownership actually buys you day to day

Owning the files is not just insurance for the day you leave. It changes what the tool can do while you stay.

• Every AI reads the same memory. Callosium talks to assistants over MCP (Model Context Protocol, the open standard AI apps use to plug into outside tools). Whatever you tell one, the next one already knows.
• You decide what each AI can see. Each connected assistant is limited to the folders you allow, from a dashboard, without touching a config file.
• Every write is signed. The server stamps each new note with which AI wrote it, so the record cannot be faked. Pieces of this exist elsewhere, but I have not found both paired in something a normal person can actually run.
• It works with no key and no internet. Everyday recall runs on your machine, with no large language model in the core and no paid API. Here is more on what still works with the wifi off.
• It says "that is not in your notes." When the answer is not in your folder, it tells you, instead of inventing something confident and wrong. And when it does answer, it cites the exact note.

What I am not claiming

I am not claiming Callosium beats Mem0 or Zep on their published benchmarks. The paper does not claim it and neither do I. Other local tools also give you plain files, which is a real thing they get right, and Basic Memory is one of them. What none of them do, as far as I could verify, is keep the files yours after money changes hands, limit what each AI can see, and record which AI wrote what.

Every number in the white paper is reproducible. The question generator and the grader ship in the repo, read your own vault, and build the test out of your own notes, so you can check my work on your material instead of taking my benchmark on faith.

The point of a second brain is that it is yours

That line closes the paper, and it is the reason I built Callosium instead of using something that already existed. Yours should not mean yours until the card declines. It should mean plain files, on your disk, in your cloud drive if you want sync, readable in ten years by software that has not been written yet.

The core is free forever and open source under Apache-2.0. Early access opens on 4 August 2026, and the waitlist is on the homepage. English and Arabic work equally well, which mattered to me personally and turned out to matter to a lot of other people too.

Abdo

Yours should not mean yours until the card declines.

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