Midplane README

A gateway between AI agents and your Postgres databases.
Every statement is checked against your policy and recorded before it runs.

Quickstart · Documentation · Midplane Cloud

Agents get useful once they can read your real tables, but a database role that reads every column and writes every row is not a control you can show a security reviewer. Midplane is that control. Agents connect to the gateway over MCP; it parses each statement with Postgres' own parser, decides it against your policy, records it, and only then runs it, with masks written into the query itself.

Claude Code on the quickstart's sample database: emails come back hashed and phones cut to their last four digits; a support ticket carries a prompt injection asking for the API keys; once the agent has read it, Midplane denies the api_keys table.

What it enforces

Table access, denied by default, per table.
Masking at the source: hashes, partial values, generalized dates, NULLs, applied before any filter, join or aggregate sees the raw value.
Guardrails: one statement at a time, writes need a WHERE, no writes hidden in a WITH, reads in read-only transactions with timeouts.
Approvals: writes held for a person, bound to the exact statement and checked against the row count the approver saw.
Containment: once an agent reads a column labeled untrusted (support tickets, emails), its writes are held and secret tables are closed to it.
An audit log on the gateway's own disk, hash-chained, exported and verified with one command.

The gateway runs in your network, next to your databases, and opens every connection itself.

mermaid

flowchart LR
  agent["Agent"] -->|"MCP"| gateway
  subgraph network ["Your network"]
    gateway["Gateway"] -->|"SQL, as its own role"| postgres[("Postgres")]
  end
  gateway -->|"outbound only"| cloud["Midplane Cloud"]

Get started

A sample database, no account: the quickstart below.
Your own database, with Midplane Cloud, for policy in a dashboard, approvals and a query log; the cloud never holds a database credential or sees a row. Follow get started. Midplane Cloud is invite-only for now: get access.
Your own database, no account: local mode.

The gateway is the midplane npm package, run with npx, or the image ghcr.io/midplaneai/midplane. Both are built from this repository's tags with provenance, and the image is signed: verifying a release.

Quickstart

You need Node 24.16 or newer, Docker, and an MCP client such as Claude Code.

git clone https://github.com/midplaneai/midplane.git
cd midplane/examples/quickstart
docker compose up -d --wait

Then follow its steps: a sample shop database and the gateway in local mode, with nothing leaving your machine. Ask your agent:

Ask	What happens
"List our customers with their emails and phone numbers."	Emails hashed, phones cut to the last four digits, signup dates to the month
"Delete all support tickets."	Denied: a write needs a `WHERE`
"Mark ticket 2 as closed."	Held for approval; local mode has nobody to ask, so it's refused
"Summarize ticket 1."	Its body carries a prompt injection; reading it taints the agent
"Now show me the API keys."	Denied: a tainted agent can't read secret tables

In Midplane Cloud, Try with sample data runs the same sample linked, where the held write waits for your approval instead.

Documentation

midplane.ai/docs: how it works, deploying the gateway, configuration, masking, approvals and taint, audit and troubleshooting. Its source is in docs/.

Contributing

Bugs and questions go to issues; building and testing is in CONTRIBUTING.md. Found a way around a mask, a policy or the audit log? Report it privately: SECURITY.md.

License

MIT, see LICENSE.