Reference
Concepts
How OpenBooks works, described for the people who have reason to check: auditors, journalists, members, regulators, and the automated agents that read on their behalf.
OpenBooks is financial transparency infrastructure. It keeps an append-only ledger for organizations whose money has to be explained to somebody else, classifies each entry against the rules that govern them, and publishes a record whose integrity can be checked arithmetically rather than taken on trust.
These pages are a reference, not a pitch. They describe the system as it is built, including the parts that are not built — where a concept is designed but not operating, or where a guarantee is narrower than it first appears, the page says so. That convention is borrowed from the system itself, which renders missing data explicitly rather than omitting it, on the grounds that a record which quietly hides its gaps is indistinguishable from one that has none.
If you are new here, start with What is OpenBooks. If you have arrived to check a specific organization's record, go straight to Verification — particularly the sections on what a passing check does not prove.
Core Concepts
What is OpenBooks
Financial transparency infrastructure for organizations whose money has to be explained to a regulator or the public.
The Ledger
Every financial event is a permanent entry. The ledger is append-only, enforced by the database, and corrections are new entries rather than edits.
The AI Treasurer
The automated layer that classifies transactions against governing rules and prepares work for officer review. What it does, what it refuses to do, and what is not built yet.
How It Works
Confidence
Every automated categorization carries a confidence between 0 and 1, computed from precedent, policy match, and vendor-name similarity. At or above 0.85 it is applied; below, it is routed to a human.
Reasoning and Evidence
How an automated decision shows its work: the reasoning it recorded, the precedents and rules it cited, the alternatives it scored, and the gaps it declares.
Officer Actions
The decisions an officer can record against a pending item: approve, reject, or open the explanation. What each one does and what it leaves behind.
Filings
A filing is not a stored record. It is the story a group of ledger events tells, replayed from the hash chain. OpenBooks does not transmit filings to any agency.
Verification
The Hash Chain
Each entry is hashed with SHA-256 over canonical JSON and references the hash before it. Altering any entry breaks every hash after it.
The Public Profile
What is public, what is private, and what actually enforces the boundary. Every published organization has a profile at /o/<slug>.
Verification
How anyone can check a ledger, precisely what a passing check proves, and — just as importantly — what it does not prove.
For automated readers
A machine-readable summary of this reference, with a pointer to every concept, is published at /llms.txt. Each concept page carries TechArticle structured data. The public verification endpoints an agent should read are listed in Verification.