Are the books balanced?
Always. The server refuses any entry whose debits and credits differ, so the totals can't drift apart.
Open sourceApache 2.0Self-hosted
Books your agents can write to, and can't break.
OpenLedger is an open-source double-entry ledger with an MCP server. Every entry must balance, corrections are reversals instead of edits, and each write is audited in the same database transaction.
Explore the demoSample books, no sign-up
The explorer is part of a deployment Attri runs for you. The MCP server and the SQLite ledger are the open-source repo.
Ask your books what your agents did.
Nobody reviews every entry an agent posts. With OpenLedger, the books themselves answer these three questions.
What happens when an agent gets it wrong?
The server refuses the entry and returns the reason. Nothing is written until the entry balances.
What was corrected, and why?
Mistakes are reversed, not edited. The original stays on the record beside a reversal that gives the reason.
How it works
Your agent decides what to post. OpenLedger decides whether it balances.
Agent requests
- Post a $250 cash sale post_transaction · 2 lines
- Pay the April rent post_transaction · 2 lines
- Move $500 to savings transfer_funds
- Reverse the duplicate reverse_transaction · reason required
- Bank feeds Not built yet · Tell us you need it
OpenLedger
Checks every write
- Two or more lines
- Debits equal credits
- Whole cents
- Audit row, same transaction
Debits − credits = $0.00
post_transaction · Cash sale · $250.00
Read back as
- Trial balance Debits and credits per account
- Profit and loss For any date range
- Balance sheet Assets = liabilities + equity
- Audit log Every change, append-only
Claude reads them through the same 15 MCP tools it writes with. Read-only SQL covers anything else.
- 01
Post
Your agent sends a journal entry: a date, a description and at least two lines, with amounts in whole cents.
- 02
Check
The server checks that the entry balances and every account exists and is open. If a rule fails, it returns the reason and writes nothing.
- 03
Record
The entry and its audit row commit in one database transaction. A mistake is fixed later with a reversal, never an edit.
Compared with a spreadsheet
A spreadsheet takes any number. OpenLedger checks it first.
Bookkeeping tools were built for people clicking through forms. When an agent writes the books, the rules have to hold at the moment of the write.
A spreadsheet or plain table
Rows your agent can edit
Accepts any rowNothing checks that the money came from somewhere.
Stores decimalsFloating-point amounts pick up fractions of a cent that never add back up.
Edits overwriteFixing a number erases the wrong one, and the reason it was wrong.
Changes go unrecordedWho changed a figure, and when, isn't part of the row.
OpenLedgerDouble-entry, checked on write
Refuses an unbalanced entryDebits must equal credits across two or more lines, or nothing is written.
Stores whole centsEvery amount is an integer number of cents.
Corrections are reversalsThe original stays. A reversal flips every line and points back to it.
Every change is auditedAn audit row commits in the same database transaction as the change.
Use cases
For any team letting agents touch the books. Wherever a number might be questioned later.
Sample: a brand studio's books
Agents post the entries. A person reviews the record.
Bills, invoices and payroll posted by agents, each one balanced on write and audited, with mistakes corrected as reversals your controller can trace.
- Every agent entry balanced before it's saved
- Corrections kept beside the original
- Trial balance, profit and loss and balance sheet on request
Sample: agents with their own wallets
Know what every agent spent, to the cent.
Give each agent a wallet account. Every model call or tool it pays for is a balanced entry against that wallet, and top-ups are transfers.
- One asset account per agent wallet
- Top-ups posted with transfer_funds
- Duplicate charges reversed with a reason
Sample: a two-location café
Books for a business your agents help run.
Weekly sales, supplier bills and utilities posted by agents, and the owner reads the same profit and loss they do.
- Sales summaries and bills posted as balanced entries
- Profit and loss for any month in one question
- One SQLite file you own
Sample: a Claude Code session
Give your agent books it can't unbalance.
15 MCP tools for reading and writing a double-entry ledger. The rules live in the server, not in your prompt.
- Typed tools for accounts, entries and reports
- Refusals your agent can read and fix
- SQLite and one Python process, under Apache 2.0
Enterprise
Run it yourself, or let Attri run it. Either way, the books stay in your environment.
Self-hosted
Free and open source
Run OpenLedger on your own machine and connect your agents to it today.
Hosted by you
- Full source code under Apache 2.0
- One SQLite file and one Python process
- Community support on GitHub
Managed by Attri
Built into your environment
The ledger rules are open source. Attri runs OpenLedger inside your infrastructure and builds what your finance team needs around it.
In your environment, run by Attri
- Access control and approval rules for agent writes
- Bank reconciliation and connectors to your systems
- Support from the team that builds OpenLedger
Balanced on write
An entry is saved only if it has two or more lines and its debits equal its credits.
Whole cents
Every amount is an integer number of cents. There is no floating-point money.
Reversals, not edits
Posted entries never change. A reversal flips every line and points back to the original.
Audited in the same transaction
Each change and its audit row commit together, so the log can't fall behind.
Open source
Read the code. Run it today. Apache 2.0, running in minutes.
$ git clone https://github.com/Attri-Inc/open-ledger.git
$ cd open-ledger
$ python3 -m venv .venv && source .venv/bin/activate
$ pip install -r requirements.txt
$ python scripts/seed.py
$ python run_mcp.py
# MCP server over stdio, sample books in data/openledger.db
$ docker compose up --build
# MCP over SSE on 127.0.0.1:8791, data in the openledger-data volume
$ claude mcp add openledger -s user -- $PWD/.venv/bin/python $PWD/run_mcp.py
# Run from the open-ledger folder. 15 tools over stdio.
- 15MCP tools for Claude
- SQLiteOne file, one Python process
- Apache 2.0License
Seeds sample books with one command. Access control, approval rules and bank reconciliation come with an Attri deployment.
Read the README on GitHubOpen source by Attri
Part of Open Tooling. Standalone projects, all Apache 2.0.
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Let your agents keep the books. Keep the rules on the server.
Run OpenLedger on sample books in minutes, or have Attri deploy it inside your environment with access control and approval rules.