MCP server Keyfold

Keyfold core

The open-source parts of Keyfold, an offline-first vault for developers: API keys organised by project and environment, plus passwords, in one encrypted file. No account, no cloud, no telemetry.

The Keyfold app for Mac is built on these crates (Windows is coming through the Microsoft Store). Get it at keyfold.app/download; signed builds are also on the Releases page.

What is here

Crate	What it does
crates/keyfold-core	Argon2id key derivation, XChaCha20-Poly1305 envelope encryption, the tamper-evident vault format, rolling backups, the Recovery Kit, .env parsing, key detection patterns, 2FA codes (RFC 6238) and offline Ed25519 licence verification
crates/keyfold-agent	The JSON-line protocol between the keyfold CLI and the running app, over an owner-only local socket
crates/keyfold-cli	The keyfold command line and the MCP server for Cursor and Claude Code. No tool returns a secret value; every request is approved in the app

Use it with an AI agent (MCP)

keyfold mcp lets Claude Code, Cursor, Codex, Gemini CLI and other MCP clients use your API keys without the model seeing them. Its seven tools list project and key names, write a .env file you approve, run a command with the keys injected, store a key, create a project and import a .env file. None of them returns a secret value. Every request waits for your click in the Keyfold app, which shows the command or file the keys are for.

1. Install Keyfold for Mac. In the app, open Settings › General › Command line and MCP and click Install, which puts keyfold on your PATH.
2. Add the server to your client:

claude mcp add --scope user keyfold -- keyfold mcp

Cursor (.cursor/mcp.json): { "mcpServers": { "keyfold": { "command": "keyfold", "args": ["mcp"] } } }

A command you approve can still print a key, and the model reads what it prints; the MCP guide covers that and one-hour approvals. The server needs the Keyfold app running and unlocked on the same Mac. The Dockerfile builds it on Linux only so that MCP directories can read its tool list.

MCP Registry name: mcp-name: io.github.codewithkolin/keyfold

Docs

• Vault format: every byte of the file, and how it is authenticated.
• Threat model: what Keyfold protects against, and what it cannot.
• MCP and CLI guide: connecting an AI agent without showing it your keys.

Build and test

cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings
cargo build --release -p keyfold-cli   # the `keyfold` binary

Rust stable, no other toolchain needed.

Security

Please report vulnerabilities privately; see SECURITY.md.

Licence

AGPL-3.0-only. See the LICENSE file in each crate. The Keyfold desktop app around these crates is proprietary.