Universal Ledger Protocol (ULP)

An open protocol for secure, standardized business document exchange.

ULP enables any accounting system, ERP, or SaaS to exchange invoices (and other business documents) without CSV conversion, manual entry, or proprietary integrations. Think of it as HTTP for accounting — a universal transport layer for business documents.

Why ULP?

Today, exchanging invoices between systems requires:

• CSV export → manual mapping → import
• Proprietary API integrations per vendor
• EDI systems that cost millions to implement

ULP solves this with:

• One open format any system can implement
• Hash-chain integrity (Git-style, not blockchain — zero energy waste)
• Envelope architecture that carries any document type
• Cryptographic proof that documents haven't been tampered with

Quick Start

# Install
npm install

# Build
npx tsc

# Run gateway node (port 3000)
node dist/server.js

# Run receiver node (port 3001)
node dist/receiver.js

# Send a test invoice
curl -X POST http://localhost:3000/api/send-invoice \
  -H "Content-Type: application/json" \
  -d '{
    "invoice_id": "INV-001",
    "sender_id": "company-a",
    "receiver_id": "company-b",
    "amount": 50000,
    "currency": "JPY",
    "issue_date": "2026-04-06",
    "due_date": "2026-05-06"
  }'

# Audit the ledger
node dist/auditor.js

Documentation

• Protocol Specification — Full technical specification
• Envelope Format — Document envelope schema
• Invoice Schema — Invoice payload definition
• Hash Chain — Integrity verification mechanism
• API Reference — HTTP endpoint specification

Architecture

┌─────────────┐         ┌─────────────┐         ┌─────────────┐
│  System A    │         │  ULP Node   │         │  System B    │
│ (Worksgrid)  │──POST──▶│  (Gateway)  │──POST──▶│ (Any ERP)   │
│              │◀─────── │             │ ◀───────│              │
└─────────────┘  hash   └──────┬──────┘  hash   └─────────────┘
                               │
                        ┌──────▼──────┐
                        │   Ledger    │
                        │ (Hash Chain)│
                        └─────────────┘

Design Principles

1. Open — MIT licensed, no vendor lock-in
2. Simple — Any developer can implement a client in a day
3. Secure — Hash-chain integrity, digital signatures
4. Lightweight — No blockchain, no mining, no consensus overhead
5. Extensible — Envelope carries invoices today, any document tomorrow

License

MIT

Contributing

ULP is an open protocol. Contributions, implementations in other languages, and feedback are welcome. See CONTRIBUTING.md.