# OpenLedger – Local-first double-entry accounting, MCP-native (Apache 2.0)

> Source: <https://github.com/Attri-Inc/open-ledger>
> Published: 2026-09-07 02:47:58+00:00

**Local-first double-entry accounting, queryable by humans and agents.**

SQLite-backed ledger. MCP server with 15 tools. Immutable transactions, contra-posting corrections, append-only audit log.

Part of a family of local-first agent services: open-crm (memory) · openwatch (observability) · **openledger (money)**.

```
cd open-ledger
python3 -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
python scripts/seed.py            # bootstrap a fresh dev DB with sample books
python run_mcp.py                 # stdio transport (default)
```

For Claude Code:

```
claude mcp add openledger -s user -- \
  /absolute/path/to/open-ledger/.venv/bin/python \
  /absolute/path/to/open-ledger/run_mcp.py
```

See [docs/claude-connector.md](/Attri-Inc/open-ledger/blob/main/docs/claude-connector.md) for the full setup.

```
                ┌─────────────────────────────────────┐
                │          SQLite ledger              │
                │  accounts · transactions ·          │
                │  entry_lines · audit_log · settings │
                └──────────────────┬──────────────────┘
                                   │
                                   ▼
                         MCP server (stdio / SSE :8791)
                         15 tools — reads + safe writes
                                   │
                                   ▼
                         Claude Desktop, Claude Code,
                         agent frameworks
```

A layered architecture (SOLID): the transport, business rules, and persistence
are separated, and each depends only on the layer's abstraction — not its
implementation. Swapping SQLite for Postgres later touches only `repositories/`
and `container.py`.

```
src/
├── domain/          pure constants + typed error hierarchy (no I/O)
├── infrastructure/  Database connection, Unit of Work, id/clock helpers
├── repositories/    protocols.py  — narrow Reader/Writer contracts
│                    sqlite.py     — the only code that writes SQL (aiosqlite)
├── services/        accounts · ledger · reports (Strategy) · audit · query
│                    — the only layer with business rules / invariants
├── serialization.py response/error envelope helpers
├── container.py     composition root — wires SQLite repos into services
└── mcp_server.py    thin MCP transport adapter over the services
run_mcp.py           stdio entry point for Claude Desktop / Code
scripts/             seed.py (sample data) · schema.sql · smoke_test.py
tests/               service-level tests of the core invariants
```

Querying is **raw parameterized SQL over `aiosqlite`** (no ORM); all SQL lives
behind the repository protocols, so services never see a query.

1. Every transaction has ≥ 2 entry lines and `sum(debits) == sum(credits)` — enforced
in the write path inside one DB transaction.
2. All amounts are **integer minor units (cents)** . No floats anywhere.
3. Transactions and entry lines are **immutable** . Corrections happen via`reverse_transaction` (contra posting), never UPDATE/DELETE.
4. Every mutation writes an audit-log row **in the same DB transaction** .

| Group | Tools | 
|---|---|
| Accounts | `list_accounts` ·`get_account` ·`get_balance` ·`get_account_ledger` ·`create_account` | 
| Journal | `get_transaction` ·`search_transactions` ·`post_transaction` ·`transfer_funds` ·`reverse_transaction` | 
| Reports | `get_trial_balance` ·`get_profit_loss` ·`get_balance_sheet` | 
| Audit | `get_audit_log` | 
| Escape hatch | `run_query` (SQL`SELECT` only) | 

| Env var | Default | Notes | 
|---|---|---|
| `OPENLEDGER_DB` | `./data/openledger.db` | SQLite path | 
| `MCP_TRANSPORT` | `stdio` (via`run_mcp.py` ) | `stdio` or`sse` | 
| `MCP_PORT` | `8791` | SSE only | 

- "How much cash do we have right now?"
- "Show me the P&L for January."
- "Are the books balanced?" (trial balance)
- "Post a $250 cash sale for today."
- "Move $500 from Wallet A to Wallet B."
- "What was reversed recently, and why?"

Contributions welcome — see [CONTRIBUTING.md](/Attri-Inc/open-ledger/blob/main/CONTRIBUTING.md) and our
[Code of Conduct](/Attri-Inc/open-ledger/blob/main/CODE_OF_CONDUCT.md). Report vulnerabilities per [SECURITY.md](/Attri-Inc/open-ledger/blob/main/SECURITY.md).

Licensed under the **Apache License 2.0** — see [LICENSE](/Attri-Inc/open-ledger/blob/main/LICENSE).