What's a Hub?

By default, Treeline is fully local: one tl binary, one DuckDB file on your machine, nothing on a network. A Hub is the optional layer that lets you go beyond a single machine — to use Treeline on more than one device, and to reach your finances from your phone or a cloud AI.

What a Hub is

Run tl serve on any Treeline instance and it becomes a Hub — an HTTP server that:

lets your other linked Treeline instances push and pull their data, and
exposes an MCP endpoint (/mcp) so AI agents can reach your data over the network.

A Hub isn’t a separate app or a product you install. It’s just Treeline running in serve mode. The instance you run tl serve on holds the copy of your data that everything else pushes to and pulls from.

Do you actually need one?

If you use a single machine and your AI agent runs there too, probably not. For AI, the deciding factor is how the agent connects:

Agent on the same machine that can launch tl itself — Claude Desktop, Claude Code, Cursor — connects with tl mcp (MCP over STDIO). No Hub needed. See MCP Server.
Agent over the network that can’t spawn a local process — Claude on your phone, ChatGPT, claude.ai — needs an HTTP endpoint to reach. That’s a Hub.

And if you simply want your data on more than one device, a Hub is the shared point they push to and pull from.

How instances connect

Your devices link to one Hub and push and pull through it — a hub-and-spokes arrangement, not peer-to-peer. One instance serves; the others run tl hub link and push/pull against it. A Hub is meant for a small number of linked devices — a couple of your own machines, or a household sharing one Hub — not large-scale or widespread use.

Where to run it

Where you run tl serve is a spectrum:

On your own machine — your laptop or desktop serves its own data; reach it from other devices on your network or through a tunnel. Nothing to deploy, but it’s only reachable while that machine is awake.
On an always-on host — run the Hub container on a homelab box, a VPS, or a provider like Fly, so it’s reachable even when your laptop is asleep.

Either way, once it’s running you link your devices and connect agents.