Everyone's suddenly building company brains. Nobody agrees on...
Femke Plantinga@femke_plantinga
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Aug 27, 2026
~2 min read
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Everyone's suddenly building company brains.
Nobody agrees on what's inside one. ๐ตโ๐ซ
So we opened up 9+ company brains to see how they're actually built.
Every single one does the same four things: getting signals, remembering, dreaming & pruning, speaking & searching.
๐ญ. ๐๐๐ฟ๐ฎ๐ถ๐ป
Garry Tan's open-source personal brain. Your email and calendar flow into a git repo, and a nightly job re-links everything and flags what's gone stale.
๐ฎ. ๐บ๐ฒ๐บ๐ฌ
A memory library you call from your own code. It only stores what you explicitly tell it to, and ranks fresh facts above idle ones at search time.
๐ฏ. ๐๐ฒ๐๐๐ฎ
For building agents that remember across sessions. The agent decides what's worth keeping, and a second agent tidies up its memory in the background.
๐ฐ. ๐ญ๐ฒ๐ฝ / ๐๐ฟ๐ฎ๐ฝ๐ต๐ถ๐๐ถ
A knowledge graph with a clock in it. When a fact changes, the old one gets an end date instead of being overwritten, so you can still ask what was true last March.
๐ฑ. ๐ฆ๐๐น๐ฝ๐ต
A content brain that lives entirely in a git repo. Agents write drafts, humans publish, and afterwards the agent reads your edits to learn what it got wrong.
๐ฒ. ๐๐๐ฌ (๐๐น๐ฎ๐๐ฑ๐ฒ ๐๐ผ๐ฑ๐ฒ + ๐ด๐ถ๐)
What most engineering teams actually do. Markdown in the repo, grep instead of search, and pull requests as the only thing keeping it honest.
๐ณ. ๐ฃ๐น๐ฒ๐๐ผ๐ฟ
A brand brain for marketing teams. Campaigns, assets and performance data in one tree, and the brand rules only move when a human signs off.
๐ด. ๐๐ผ๐ฟ๐ด๐ถ๐ฎ๐ ๐๐ผ๐ฟ๐๐ฒ๐
Built in-house by an eight-person AI team. 12,000 markdown nodes in GitHub, and every night the questions it got wrong become PRs that fix it.
๐ต. ๐ฆ๐น๐ถ๐๐ฒ ๐๐ด๐ฒ๐ป๐
For teams whose knowledge lives in docs and across sources. It watches ~20 connected tools (Slack, Drive, GitHub, Jira, etc.) for what's gone stale and sends the diff to whoever owns the page. Nothing changes without human approval.
We just launched an interactive ebook with architecture notes from real 149 teams of builders and users, interview insights, and the complete research.
The ebook is free, get it here: slite.com/ebooks/companyโฆ
Which brain would you pick? ๐ง
Nobody agrees on what's inside one. ๐ตโ๐ซ
So we opened up 9+ company brains to see how they're actually built.
Every single one does the same four things: getting signals, remembering, dreaming & pruning, speaking & searching.
๐ญ. ๐๐๐ฟ๐ฎ๐ถ๐ป
Garry Tan's open-source personal brain. Your email and calendar flow into a git repo, and a nightly job re-links everything and flags what's gone stale.
๐ฎ. ๐บ๐ฒ๐บ๐ฌ
A memory library you call from your own code. It only stores what you explicitly tell it to, and ranks fresh facts above idle ones at search time.
๐ฏ. ๐๐ฒ๐๐๐ฎ
For building agents that remember across sessions. The agent decides what's worth keeping, and a second agent tidies up its memory in the background.
๐ฐ. ๐ญ๐ฒ๐ฝ / ๐๐ฟ๐ฎ๐ฝ๐ต๐ถ๐๐ถ
A knowledge graph with a clock in it. When a fact changes, the old one gets an end date instead of being overwritten, so you can still ask what was true last March.
๐ฑ. ๐ฆ๐๐น๐ฝ๐ต
A content brain that lives entirely in a git repo. Agents write drafts, humans publish, and afterwards the agent reads your edits to learn what it got wrong.
๐ฒ. ๐๐๐ฌ (๐๐น๐ฎ๐๐ฑ๐ฒ ๐๐ผ๐ฑ๐ฒ + ๐ด๐ถ๐)
What most engineering teams actually do. Markdown in the repo, grep instead of search, and pull requests as the only thing keeping it honest.
๐ณ. ๐ฃ๐น๐ฒ๐๐ผ๐ฟ
A brand brain for marketing teams. Campaigns, assets and performance data in one tree, and the brand rules only move when a human signs off.
๐ด. ๐๐ผ๐ฟ๐ด๐ถ๐ฎ๐ ๐๐ผ๐ฟ๐๐ฒ๐
Built in-house by an eight-person AI team. 12,000 markdown nodes in GitHub, and every night the questions it got wrong become PRs that fix it.
๐ต. ๐ฆ๐น๐ถ๐๐ฒ ๐๐ด๐ฒ๐ป๐
For teams whose knowledge lives in docs and across sources. It watches ~20 connected tools (Slack, Drive, GitHub, Jira, etc.) for what's gone stale and sends the diff to whoever owns the page. Nothing changes without human approval.
We just launched an interactive ebook with architecture notes from real 149 teams of builders and users, interview insights, and the complete research.
The ebook is free, get it here: slite.com/ebooks/companyโฆ
Which brain would you pick? ๐ง
