Several Mac apps work as an MCP client, so a model can use the tools an MCP server offers: Claude Desktop, goose, LM Studio, Jan, Msty and Grux OS among them. They differ in the model behind the tools. Claude Desktop puts Claude, through your Claude account, in front of MCP servers. goose (Apache 2.0) is an open source general agent that the MCP project lists as a client. LM Studio and Jan run local models and can call MCP tools from their chat. Msty Studio lists MCP tools in its Toolbox, limited on the free tier. Grux OS (MIT) is a client and a server. It launches each MCP server you add as a local process, talks to it over stdio, and hands its tools to Chat beside its own built in tools, with the server's secrets kept in your Keychain. It also runs a read only MCP server of its own, so another agent can drive Grux. Pick by the model you want behind the tools.
Grux OS 3.0.0 · last checked 2026-09-30 · generated from the shipping release
You add each server yourself: a name, a launch command, its arguments and the names of the environment variables it needs. Nothing is discovered for you.
Secrets stay out of the config file. The file stores variable names only; the values, and any OAuth tokens, live in the macOS Keychain.
Each server runs as a local process that Grux starts, speaks JSON-RPC to over stdio, and restarts within a bounded budget if it crashes.
The other direction is read only. Grux's own MCP server lets an outside agent read through the same tools you use; writes go over a Unix socket instead.
Where another client is the better choice
You want Claude as the model and do not mind a Claude account: Claude Desktop.
You are on Windows or Linux: goose, LM Studio or Jan.
You want MCP tools inside a model testing app: LM Studio.
Both. As a client it connects to MCP servers you add and gives their tools to Chat. As a server it lets another agent drive Grux, read only, through grux serve.
Where does Grux keep an MCP server's API keys?
In the macOS Keychain. Grux's MCP config file on disk holds only the names of the environment variables a server needs, never their values.
Is there a free, open source MCP client for Mac?
Yes. Grux OS (MIT), goose (Apache 2.0) and Jan (Apache 2.0) are open source and free, and all three run on a Mac.