AI bookkeeping software
An AI that keeps books as you, on your firm's rules
Mastro's AI is your own Claude, connected to your clients' books. It does the routine work of the month, and your firm decides what it may do.
The work
What it does in a client's month
Categorizes new bank lines
A category for each line no rule covers, from the client's chart and how its past lines went, with the reason.
Follows up with the client
Questions about lines it can't place, drafted for the client's portal, sent when your firm lets it.
Prepares the close
What still blocks the month, what looks unusual against last month and last year, and a summary for the client.
Answers from the books
Balances, reports, and where the close stands, read live from Mastro, with where each number comes from.
Drafts rules and entries
A rule from what keeps recurring, or the entry that closes the month, each with its reason.
Shows Mastro's own screens
The review queue, a reconciliation, or the month-end close, in the chat, to approve with a click.
The rules
What holds, whatever it's asked
- It works as a personSigned in as you, with exactly your access: the clients you can see, and nothing more.
- Your firm sets each areaPosting, rules, invoices and bills, reconciling and closing, payroll, taxes, what goes to clients: it does it, asks first, or can't.
- Asking first means a person approvesThe change waits in one review queue with its reason. Approving it is always someone's click.
- Rules stay deterministicMastro runs no model of its own, so the same books and rules always post the same way.
- Numbers stay maskedTax ID, bank account, and card numbers reach it as their last four digits; employees' pay never does.
- Everything is on the recordEach thing it reads, suggests, or does is in the client's activity feed.
Questions
About the AI
Which AI is it?
Claude, by Anthropic: each person's own Claude plan, on the web, the desktop, or Claude Code, connected to Mastro. Another app that speaks MCP can connect the same way.
Does Mastro train AI on client books?
No. Mastro runs no model and trains none. On a Claude Team or Enterprise plan, Anthropic doesn't train on your conversations either.
Do I need an API key?
No. The AI runs on each person's own Claude plan, so Mastro's price never carries the cost of tokens.
Can it post to the books without approval?
Only in the areas your firm sets to "does it". Everywhere else the change waits for a person, or the AI can't make it at all.
What does it cost?
The AI module is $29 a client a month, or $290 a year ahead, beside each person's own Claude plan. It's less in a package with other modules.