pastoon

Auto-convert clipboard JSON to TOON — 40% fewer LLM tokens, zero friction.

What it does

Every time you copy JSON, pastoon silently converts it to TOON format before you paste — saving ~40% of tokens in LLM chat UIs, coding agents, and API calls.

JSON (verbose):                    TOON (40% fewer tokens):
{                                  users[3]{id,name,role}:
  "users": [                         1,Alice,admin
    {"id":1,"name":"Alice",          2,Bob,user
     "role":"admin"},                3,Carol,user
    ...
  ]
}

TOON is lossless — perfect JSON round-trip, same data model, just without the braces, quotes, and repeated keys.

Install

npm install -g pastoon
pastoon setup

That's it. The [P] icon appears in your menu bar. Every JSON you copy is automatically converted.

Supports macOS (LaunchAgent), Linux (systemd user service), and Windows (registry Run key).

Agent install

If you use a coding agent (Claude Code, OpenCode, Cursor, Windsurf), give it SETUP.md:

"Set up pastoon for me using the instructions in docs/SETUP.md"

MCP server

pastoon exposes two MCP tools for agents working with JSON in context:

pastoon mcp add   # register with detected coding agents
pastoon --mcp     # start MCP server manually

Tools:

• json-to-toon — convert JSON string to TOON (use before reasoning over large JSON)
• toon-to-json — convert TOON string back to JSON

CLI

pastoon            # JSON → TOON (clipboard)
pastoon --reverse  # TOON → JSON (clipboard)
pastoon --pipe     # stdin → stdout (for scripts)

pastoon setup      # install background service + start tray
pastoon stop       # stop tray
pastoon start      # start tray
pastoon uninstall  # full removal

What is TOON?

TOON (Token-Oriented Object Notation) is a compact, human-readable format for JSON data. It achieves:

• ~40% fewer tokens than JSON
• 76.4% LLM accuracy vs JSON's 75.0%
• Perfect lossless round-trip
• Spec-driven with implementations in TypeScript, Python, Go, Rust

License

MIT