Postern

The Personal Context Gateway. Connect the sectors of your life once — finance, health, mail, contacts, calendar, home — and reach them from any agent through one surface. Read them, and act on them where the source allows.

Postern runs on your own machine, and there is nothing in the middle: no account, no sign-up, no model provider in the loop, no correlation across your domains behind your back. Nothing leaves the box unless you ask it to.

getpostern.com is the front door — the live demo, and a field guide for every provider.

Set it up

Postern runs on any computer that stays on — the one in front of you, or a spare machine at home. Two ways in.

With your agent

This is the path Postern was built for. Point your coding agent — Claude Code, Cursor, Codex, anything that can read files and run commands — at setup-with-your-agent.md and say:

Follow https://raw.githubusercontent.com/getpostern/postern/main/setup-with-your-agent.md and set Postern up for me.

That file is a contract, not a tutorial — every step marked human or automatable, every command read from the gateway's own source, the whole path executed end to end by a first-time user's agent on a clean machine. The agent does about 95% of getting Postern running, Docker included. You do the parts only you can: signing in to your accounts and approving what they share. Secrets go into Postern's own screens, never into the chat.

By hand

Install Docker first (free; its site walks you through it). After that it's three lines and about five minutes — fetch Postern, give its database a password of its own, start everything:

git clone https://github.com/getpostern/postern.git && cd postern
echo "POSTGRES_PASSWORD=$(openssl rand -hex 24)" > .env
docker compose up -d

Now open http://localhost:8787 in your browser. That page is the Console — your gate's control room. It walks you through connecting your first source, and the field guides walk every provider screen by screen, with pictures.

The Gatehouse — a real gate with four sources connected, everything freshly synced. This is localhost:8787 once your first sources are in.

Three things worth knowing:

• The password line writes a safe random password into .env, where every later start finds the same one — the database keeps the first password it is ever given.

• Using it from another machine? The Console answers only on its own machine, by design. ssh -N -L 127.0.0.1:8787:127.0.0.1:8787 <your-box> brings it to your laptop; everything else — your phone's health data, hosted agents like claude.ai and ChatGPT — goes over Tailscale, all opt-in. docs/SETUP.md § Remote access walks each tier.

• What did you just install? One published, signed image (ghcr.io/getpostern/postern) and a database, listening only on 127.0.0.1. Only docker-compose.yml is truly needed — download that one file if you would rather not clone.

Building from source instead? docker-compose.dev.yml carries the build: key, and CONTRIBUTING.md has the rest. The complete self-host path — every provider, every trap — is docs/SETUP.md.

One ask: if you get it running, say what broke — open an issue for anything, even a paper cut. Early reports decide what gets fixed first.

Related MCP server: local-apple-data

What it removes

Postern is best understood by what stops being your problem.

• API discovery. Every provider is a different API with a different auth dance and a different idea of which direction money flows. Today an agent pays that cost at runtime, guessing field names and discovering sign conventions by getting them wrong. Postern pays it once, in code, and publishes a typed schema with the traps written down.

• Per-agent re-integration. Every new agent currently re-does the whole integration: its own OAuth app, tokens, connectors, permission model. With Postern you connect a source once and mint a scoped key; the next agent gets the same context in one step, under the same grants and audit trail.

• The harness ceiling. When the integration lives in the harness, leaving the harness means leaving the context. Postern is harness-agnostic on purpose: swap agents, add a second one, move clients — context, capabilities, permissions and log stay put, because they were never inside the agent.

What it deliberately does not do: no LLM runs inside the gateway, no cross-domain correlation, no derived facts written back into your store. It is a faithful cache and a dispatcher. The agent reasons; Postern authenticates, normalizes, stores, serves, and dispatches.

Three properties

• One place. One surface, one grant. A granted sector covers reading and acting across every provider in it.

• Lightning fast. Reads come from a local cache in milliseconds. fetch_live is the one read path that touches a source, and actions add no gateway overhead around the single unavoidable dispatch.

• Harness-agnostic. MCP, REST, or whatever comes next — every edge is an adapter over the same seven core primitives. There is never a second implementation.

The agent surface

Seven primitives, not a tool per question. The MCP adapter maps 1:1 onto them; the REST mirror serves the reads.

query and get_record are always cache-only and instant. query reads one sector — there are no cross-sector joins, by design; an agent fans out and correlates on its own side.

From the agent's side it looks like this — one gate, three agents each holding its own key, every read landing in the owner's ledger:

The live demo, exactly as it runs at getpostern.com.

What connects today

Home Assistant is the one that also acts, through invoke_action. Adding a source is a connector plus a schema-registry entry and a migration — never a control-plane change; see CONTRIBUTING.md.

License and model

The whole gateway is open source under Apache-2.0 — the engine, every connector, both agent edges, the Console. Nothing here is a crippled tier: the open core is the product, not a demo of it. Apache rather than copyleft for one reason: a connector or an agent written against this gateway should be publishable by anyone, on any terms, including inside a closed product.

The paid surfaces — a contextual-memory tier, a person-to-person trust layer, hosted convenience — sit beside the open core, never inside it; none of them gates anything in this repository. Contributions are inbound under the same license, by DCO sign-off — see CONTRIBUTING.md. The Postern name and door mark are not licensed with the code; see TRADEMARK.md.

A note on PCI_ and pci

Environment variables and the default database name still carry a PCI_ / pci prefix from the project's working name. Renaming them would break every existing install, so they stay. If you see PCI_MASTER_KEY or a pci database, that is Postern.

Where the detail lives