Bir Finans
A finance core that is exact to the last kuruş.
Overview
Bookkeeping and accounts management: Bir Finans
Bir Finans is the bookkeeping, accounts and finance system we build for service businesses. Customer accounts, documents, cash, bank, cheques and notes, monthly packages and quota tracking, reconciliation and period close run on one double-entry ledger; every customer balance is right to the cent.
Who it is for
- 01Agencies and service firms that work on monthly retainers
- 02Businesses that want accounts, cheques and bank in one place
- 03Finance teams that no longer want to close periods by hand
Screens are taken from a demo copy running on sample data; they contain no real customer data.
01 — Problem
For retainer clients, monthly packages, quota usage, extra work and revisions — along with collections, cheques, bank movements and VAT — were tracked in different places. Period close and client balances were calculated by hand every month.
02 — System
We built a work and finance application on a double-entry ledger in which every money record must balance debit against credit. Corrections are made by reversal, never deletion; amounts are stored as exact decimals, and foreign-currency documents post to the TRY ledger with TCMB rates and FX differences.
Period close
Every step from work entry to collection leaves a balanced ledger record.
- 01Work entry
- 02Quota calc
- 03Period close
- 04Receivable
- 05Collection
Correction → reversal entry
Bir Finans
Work entry
Quota calc
Period close
Receivable
Collection
03 — Capabilities
- 01
Double-entry ledger
No transaction is saved unless debit equals credit; typed accounts, a dedicated VAT account and void-by-reversal instead of deletion.
- 02
Current accounts
Customer, supplier, person and institution accounts; VKN/TCKN checksum validation, risk levels, Excel import/export, statements and netting/transfers.
- 03
Documents
Sales/purchase invoices, returns and quotes; line and document discounts, VAT inclusive/exclusive, numbering series, quote-to-invoice conversion and recurring documents.
- 04
Cash, bank, cheques
Statement import and matching that understands Turkish bank formats, cash counts; a full cheque and note lifecycle from portfolio to collection, endorsement or bounce, and a cheque calendar.
- 05
Quota and period engine
Contracts with price-version history, package/extra/hourly pricing, quota and revision overage; monthly period close and reopen with reason and audit.
- 06
Reconciliation and reports
A tokenised reconciliation page clients can agree to or dispute; aging, profit & loss, VAT, cash and audit reports in PDF and Excel.
04 — Impact
- 01
Period close and balance calculation for retainer clients are handled by the app.
- 02
Nothing is deleted; every correction is traceable in the ledger.
05 — For technical teams
For technical teams
Architecture, figures and the technology stack: details for the technical teams evaluating the system.
Architecture
The Next.js interface talks to a NestJS API over server-side sessions. Money POSTs carry idempotency keys, period close takes row locks, and every change lands in an audit log.
- L0Users
- Owner
- Admin
- Staff
- Viewer
- L1Interfaces
- Web app · PWA
- Reconciliation link
- L2Application
- NestJS
- Data access layer
- Audit log
- L3Modules
- Ledger
- Accounts
- Documents
- Cash & bank
- Cheques & notes
- Quota engine
- Reports
- L4Data
- PostgreSQL
- DECIMAL(19,4)
- L5External services
- TCMB rate feed
- 19,4
- decimal precision
- 4
- user roles
- ~90
- application screens
- ~293
- test cases
Technology stack
Frontend
- Next.js
- React
Backend
- NestJS
- TypeScript
Data
- PostgreSQL
Documents
- Excel
Infrastructure
- Docker