Open source · MIT · Docker-ready
A production-grade reference implementation for organisational financial reporting: multi-currency Decimal calculations under a 50 ms SLA, a digitally signed three-stage approval workflow, a real-time dashboard, tax and banking integrations, and a tamper-evident audit trail.
Exchange rates are pulled from authoritative sources (central bank feed, with an exchange API fallback), compound interest and instalment schedules are computed in Decimal to 16 places, and the final figure returns in under 50 milliseconds.
Every submitted request routes automatically to the finance manager, then the inspector, then the CEO. Each stage records a complete log entry and an RSA digital signature.
Interactive charts show report status in real time, with automatic detection of overdue instalments and out-of-range transactions, and notifications delivered over email, SMS and WebSocket.
Signed invoices are submitted to the tax authority, settlement confirmations are retrieved from the bank gateway, and double-entry vouchers are exchanged with accounting software over REST or standard XML/JSON documents.
JWT authentication, Argon2id password hashing, role-based access control, field-level encryption for personally identifiable data, and a hash-chained audit log that exposes any tampering with history.
A worked example of financial correctness in Python: exact Decimal arithmetic, a custom SQLAlchemy column type that survives SQLite's float coercion, RSA-signed state transitions, and a hash-chained audit log — all covered by 115 tests at 84% coverage.
A deployable starting point for internal reporting: replace spreadsheet and email approval chains with signed, auditable workflows that integrate with your tax authority, bank gateway and accounting software.
FastAPI on Python 3.13, SQLAlchemy 2.0 with PostgreSQL, Next.js 15 with React 19 and TypeScript, real-time updates over WebSocket, containerised with Docker Compose.
It replaces spreadsheet-and-email approval chains with a single auditable flow. Each report gets a unique reference, a calculated instalment schedule, a signed approval chain and an immutable change history — so finance teams can prove who approved what, when, and on which figures.
Binary floats accumulate error: 0.1 + 0.2 is not exactly 0.3. This system keeps the entire monetary path in Decimal with banker's rounding at 16 places, so the principal components of an amortisation schedule sum back to the original principal exactly. A custom SQLAlchemy column type also prevents SQLite from silently coercing those values to a C double.
Three ordered stages: finance manager, inspector, then CEO. Each decision is signed with an RSA-2048 key using PSS padding over a canonical payload that includes a hash of the report's financial substance. If anyone edits the amount after approval, every signature on that report fails verification and the API reports which stage broke.
Yes. Connectors ship for the Iranian tax authority (سامانه مودیان), a bank settlement gateway, and accounting/ERP systems via REST JSON or standard XML documents. All connectors are idempotent, retry with exponential backoff, and run in sandbox mode by default so demos and CI never reach a live endpoint.
Each audit entry stores the hash of the previous entry, forming a chain. Editing or deleting any historical row breaks the linkage, and the verification endpoint recomputes the whole chain and returns the exact sequence number where it broke. This is verified by tests that mutate and delete rows behind the application's back.
It is MIT-licensed and runs via Docker Compose in minutes, with 115 tests at 84% coverage and CI running lint, tests and an end-to-end smoke suite. The README documents a production checklist — move signing keys to an HSM/KMS, switch to PostgreSQL, add Alembic migrations, and move rate limiting to Redis before going live.