Both connect ideas instead of filing them, and both keep your notes as Markdown. TheBrain builds its view around one thought at a time, with every link a parent, a child or a jump. Filamental puts the whole structure in front of you at once in three dimensions, with connections you name yourself, so the shape can appear as the work does.
In TheBrain every link is one of three relationships: a parent above the thought you’re viewing, a child below it, or a jump off to the side, with its siblings to the right. It’s one of the longest-running tools in this category, and that arrangement makes a familiar structure very quick to walk, one thought at a time. It also asks you to decide what sits above what as you go.
In Filamental a connection is whatever the relationship actually is, so “funds”, “contradicts” and “depends on” are each a type you name, with its own colour, direction and pull. The whole structure stays in view at once, in three dimensions. Put things wherever helps you think, or press Dark Energy and the layout spaces each part by how connected it is, so a cluster shows itself before you’d have known to file it. If you do want a hierarchy, Layers stacks the structure in bands by type.
Why deciding early costs so much is the whole argument of premature filing.
TheBrain comes with its own assistant, Cerebro, which can summarise, search and build inside a brain, and its usage is part of TheBrain’s plans: a small daily allowance for free, and more on the paid services.
Filamental has no AI of its own, so there’s no allowance to manage. Connect Claude Desktop, Claude Code, Cursor, Codex, Gemini CLI, VS Code or Zed over MCP and it reads and edits the open space directly. Or add your own key for the provider you choose, or run a model on your own computer through Ollama or LM Studio. Every request goes straight to your provider, on your account, and nothing passes through us.
TheBrain keeps each note as a Markdown file. Filamental does the same and writes the connections into the file as well, as plain YAML at the top of each note, so the folder holds the whole structure: what each thing is, what it connects to, and which way round. Open it in any editor, commit it to a repository or point an AI at it, with Filamental closed.
Laying out a structure is lean-forward work: a full screen to see the whole of it, a keyboard for the notes, a mouse to put things where they belong. Filamental is a desktop app for Windows, macOS and Linux because that’s where this work gets done, and a space moves between your machines in whatever synced folder you already use.
Reading is different. Anyone you share a link with opens it in a browser, on a phone as readily as on a desktop, with nothing to install.
TheBrain’s desktop app is free, and what reaches beyond the desktop is metered. Sync is free up to 1,000 thoughts in private brains with 100 MB of attachments, the AI is a small daily allowance, and more of either is a monthly service.
Filamental’s Personal plan is free and permanent, with no account and no card, unlimited spaces and everything AI, since the AI is your own and the folder syncs however you already sync. The paid tier is $120 a year, or $12 a month, and covers handing work over beyond the one live link that’s free, including presenting.
For some jobs. Both connect ideas rather than filing them, and both keep notes as Markdown. TheBrain arranges thoughts around the one you’re viewing as parents, children and jumps, and keeps them in sync through its own service. Filamental is a desktop app that shows the whole structure at once in 3D, with connection types you name and the connections written into the files. A hierarchy you already know suits TheBrain, and a structure you’re still working out suits Filamental.
No. A Filamental connection is a type you name, such as funds, contradicts or depends on, with its own colour, direction and pull, and none of them has to be a hierarchy. You place nodes wherever you like in 3D, or let the Dark Energy layout space them by how connected they are. If you want a hierarchy, the Layers layout stacks the structure in bands by type.
Filamental has no AI of its own. You connect the one you already use: Claude Desktop, Claude Code, Cursor, Codex, Gemini CLI, VS Code or Zed over MCP, your own API key for the provider you choose, or a local model through Ollama or LM Studio. Requests go straight to your provider on your account, so there’s no allowance from us to manage. TheBrain includes Cerebro AI usage in its own plans.
There’s no direct TheBrain import. An AI connected to Filamental over MCP, such as Claude Code, can read notes you’ve exported or copied out of TheBrain and build a space from them, with the relationships as typed connections. Your brain in TheBrain stays exactly as it was.
No, because building a structure is desk work. Filamental is a desktop app for Windows, macOS and Linux, and a space is a folder of files, so it moves between your machines through whatever sync you already use, such as a cloud drive or a repository. Reading is different: anyone you share a link with opens it in a browser, on a phone as readily as on a desktop, with nothing to install.
Connect it to everything it touches, say why on each node, then press Dark Energy and see where it lands.