Is Osaurus open source?

Yes. Osaurus is MIT licensed, the same license as Grux OS.

Can I run both on one Mac?

Yes. They are separate apps, and both can work with local models on the same Mac.

Which open source Mac agent is best for mail and calendar?

Grux OS is built around the mail, calendar, contacts, notes and files already on your Mac, read from your own accounts with no Grux server.

Grux OS or Osaurus: which open source Mac agent fits?

Osaurus and Grux OS are the two open source AI agents built natively for macOS, and both are MIT licensed. Osaurus is a Swift harness for agents with memory, tools and identity that runs fully offline on Apple silicon. It supports Apple's Foundation Models, exposes OpenAI, Anthropic and Ollama compatible APIs, and runs as an MCP server, so other tools can build on it. Grux OS is an agent for your own day: from one Command Panel it acts on the mail, calendar, files and meetings already on your Mac, gives the agent a shell whose every command can be undone, and runs on a local Ollama model or your own key. It also writes work orders so your coding agent can change Grux itself, with your yes at each step. Choose Osaurus as an offline foundation for agents. Choose Grux for an agent that works your Mac.

Grux OS 3.0.0 · last checked 2026-09-30 · generated from the shipping release

Side by side

	Grux OS	Osaurus
License	MIT	MIT
Built in	Swift and SwiftUI, native macOS	Swift, native macOS on Apple silicon
Centre of gravity	An agent that acts on your Mac's mail, calendar, files and shell	A harness for agents with memory, tools and identity
Models	A local Ollama model, or your own Anthropic key	Offline local models and Apple Foundation Models, with OpenAI, Anthropic and Ollama compatible APIs
For other tools	A command line that drives every feature	An MCP server
Changing the app	Work orders for your own coding agent	Open source, so you can fork it

Osaurus's details are from its README, read on 2 October 2026.

Where Osaurus is the better choice

You want a fully offline agent harness to build on, with MCP built in.
You want Apple's on-device Foundation Models.
You want a larger community: Osaurus has many times Grux's GitHub following.

Where Grux OS is the better choice

You want the agent to handle your own mail, calendar, contacts, notes and meetings, with meetings transcribed on device.
You want guard rails on actions: an undoable shell, workflow questions only you answer, and dry runs that change nothing outside Grux.
You want to change the app by describing the change, and let your coding agent build it.

Where to check this

Claim	Source
Osaurus is a Swift harness for agents with memory, tools and identity	Osaurus README
Osaurus supports Apple's Foundation Models	Osaurus README
Osaurus exposes OpenAI, Anthropic and Ollama compatible APIs	Osaurus README
Osaurus runs as an MCP server, so other tools can build on it	Osaurus README
Both Osaurus and Grux OS are MIT licensed	Osaurus LICENSE
Grux writes work orders so your coding agent can change Grux itself	CHANGELOG, 3.0.0 Added

Questions

Is Osaurus open source?: Yes. Osaurus is MIT licensed, the same license as Grux OS.
Can I run both on one Mac?: Yes. They are separate apps, and both can work with local models on the same Mac.
Which open source Mac agent is best for mail and calendar?: Grux OS is built around the mail, calendar, contacts, notes and files already on your Mac, read from your own accounts with no Grux server.

Download Grux 3.0.0 Read the source

Free, MIT licensed. macOS 14 or later, Apple silicon. 23.7 MB, signed and notarized by Apple. No account, no server, no subscription.