The one-line version
OpenContext is a library you fill. Deiko is a notebook that fills itself while you point and talk. One is for knowledge you curate. The other is for the work in front of you right now.
Where OpenContext is the better tool
- You want a curated knowledge base. Conventions, architecture notes, decisions that hold for months, organised in folders of Markdown you shape yourself. That’s OpenContext’s home ground.
- You like writing context on purpose. Create a doc from the CLI, the desktop app or the web UI, or ask your agent to save one. Deiko never asks you to write anything, which also means it doesn’t hold your hand-written docs.
- You’re on Windows or Linux. OpenContext runs on all three. Deiko is macOS only.
Where Deiko is the better tool
- You don’t want to write context at all. Point at the broken thing and say what’s wrong. Deiko turns that into a brief with the screenshot attached and files it into the task it continues, without you naming anything.
- The context is on your screen. A doc can say “the price card is wrong”. Deiko hands over the crop of that card, its label and the page it sits on.
- You want to know where each piece of work stands. Every task keeps what was done, decided and left open, and the agent reports back when it finishes a brief. The next brief on that work carries it.
- Some of your chats are in the browser. ChatGPT and Claude.ai can’t call tools, so Deiko puts the task’s history inside the brief itself.
The honest overlap
Both are local, both are MIT-licensed, and both give Claude Code, Cursor and Codex an MCP server to search what you’ve kept. They sit side by side happily: OpenContext for the knowledge that outlives any one task, Deiko for the task you’re in the middle of. If you mostly type and want a doc library, OpenContext fits better. If you think out loud while looking at the bug, that’s what Deiko is for.
Practical differences
- How context gets in. OpenContext: you or your agent write documents. Deiko: from what you point at and say, plus a short report the agent saves after each brief.
- Platform. Deiko is macOS 14 or later, Apple Silicon only.
- Account. Deiko has none. No email, no password, no profile.
- Source. Both are open source under MIT. Deiko’s relay is in the repo too: read it on GitHub.
- Price. Deiko is free, no account, no card. Every Mac gets two hours of hosted transcription a month; past that it transcribes on-device, and your own Groq key has no limit. Pro is $6.99 a month, $69 a year or $169 once, for ten hours.