A personal bookkeeping application "decompiled" from the ashes of QuickBooks 2003 Pro.
Free and open source. Runs on Windows, macOS, and Linux. No Intuit activation servers required.
Get started: docker compose up — see INSTALL.md for all install options.
I ran QuickBooks 2003 Pro for 14 years for side business invoicing and bookkeeping. Then the hard drive died. Intuit's activation servers have been dead since ~2017, so the software can't be reinstalled. The license I paid for is worthless.
So I built my own replacement. I transferred all my data from the old .QBW file using IIF export/import.
The codebase is annotated with "decompilation" comments referencing QBW32.EXE offsets, Btrieve table layouts, and MFC class names — a tribute to the software that served me well for 14 years before its maker decided it should stop working.
This is a clean-room reimplementation. No Intuit source code was available or used.
- Invoices — Create, edit, duplicate, void, mark as sent, email as PDF. Auto-numbering, auto due-date from terms, dynamic line items with running totals. Print/PDF generation via WeasyPrint
- Estimates — Full estimate workflow with convert-to-invoice (deep-copies all fields and line items)
- Payments — Record payments with allocation across multiple invoices. Auto-updates invoice balances and status (draft/sent/partial/paid)
- Recurring Invoices — Schedule automatic invoice generation (weekly/monthly/quarterly/yearly) with manual "Generate Now" or cron script
- Batch Payments — Apply payments to multiple invoices across multiple customers in a single transaction
- Credit Memos — Issue credits against customers, apply to invoices to reduce balance due. Proper reversing journal entries
- Quick Entry Mode — Batch invoice entry for paper invoice backlog. Save & Next (Ctrl+Enter) with running log
- Purchase Orders — Non-posting documents to vendors with auto-numbering, convert-to-bill workflow
- Bills — Enter vendor bills (AP mirror of invoices). Track payables with status progression (draft/unpaid/partial/paid/void)
- Bill Payments — Pay vendor bills with allocation. Journal: DR AP, CR Bank
- AP Aging Report — Outstanding payables grouped by vendor with 30/60/90 day buckets
- Journal Entries — Every invoice, payment, bill, and payroll run automatically creates balanced journal entries. Void creates reversing entries
- Chart of Accounts — 39+ seeded accounts (Contractor template), 6 account types (asset, liability, equity, income, COGS, expense)
- Closing Date Enforcement — Prevent modifications to transactions before a configurable closing date with optional password protection
- Audit Log — Automatic logging of all create/update/delete operations with old/new value tracking via SQLAlchemy event hooks
- Account Balances — Updated in real-time as transactions post
- Employees — Full employee records with pay type (hourly/salary), pay rate, filing status, allowances
- Pay Runs — Create pay runs with automatic withholding calculations: Federal (progressive brackets), State (5% flat), Social Security (6.2%), Medicare (1.45%)
- Process Payroll — Creates journal entries: DR Wage Expense, CR Federal Withholding, CR State Withholding, CR SS Payable, CR Medicare Payable, CR Bank
- Tax calculations are approximate — disclaimer included. Verify with a tax professional
- Bank Accounts — Register view with deposits and withdrawals
- Bank Reconciliation — Full workflow: enter statement balance, toggle cleared items, validate difference = $0, complete
- OFX/QFX Import — Import bank transactions from OFX/QFX files with FITID dedup, preview before import, auto-match by amount/date
- QuickBooks-style period selector — All reports support preset periods (This Month, This Quarter, This/Last Year, Year to Date, Custom Date) with live refresh
- Profit & Loss — Income vs expenses for any date range
- Balance Sheet — Assets, liabilities, and equity as of any date
- A/R Aging — Outstanding receivables grouped by customer with 30/60/90 day buckets
- A/P Aging — Outstanding payables grouped by vendor with 30/60/90 day buckets
- Sales Tax — Tax collected by invoice with taxable/non-taxable breakdowns
- General Ledger — All journal entries grouped by account with debit/credit totals
- Income by Customer — Sales totals per customer with invoice counts
- Customer Statements — PDF statement with invoice/payment history and running balance
- Schedule C (Tax) — Generate Schedule C data from P&L with configurable account-to-tax-line mappings. Export as CSV
- Company Snapshot with Total Receivables, Overdue Invoices, Active Customers, Total Payables
- AR Aging Bar Chart — Color-coded stacked bar (Current/30/60/90+ days)
- Monthly Revenue Trend — Bar chart showing last 12 months of invoiced revenue
- Recent invoices and payments tables
- Bank balances at a glance
- Stripe Checkout — Accept online payments via Stripe's hosted checkout page. Customers click "Pay Online" in emailed invoices, pay on Stripe, and the payment auto-records with journal entries (DR Undeposited Funds, CR A/R)
- Public Payment Page — Standalone
/pay/{token}page (no login required) shows invoice summary with "Pay with Stripe" button. Supports light/dark mode - Copy Payment Link — One-click copy of the public payment URL from the invoice view modal
- Webhook Handler — Idempotent Stripe webhook processes
checkout.session.completedevents with signature verification - Setup Guide — See SETUP_STRIPE.md
- OAuth 2.0 — Connect to QuickBooks Online via Intuit's OAuth Authorization Code flow with automatic token refresh
- Import from QBO — Pull accounts, customers, vendors, items, invoices, and payments from QBO with dependency-ordered import and duplicate detection
- Export to QBO — Push Slowbooks data to QBO with entity type mapping and ID tracking
- ID Mapping —
qbo_mappingstable tracks QBO ID ↔ Slowbooks ID per entity for dedup and re-sync - Setup Guide — See SETUP_QBO.md
- Invoice Email — Send invoices as PDF attachments via SMTP with configurable email settings. Includes "Pay Online" button when Stripe is enabled
- CSV Import/Export — Import/export customers, vendors, items, invoices, and chart of accounts as CSV
- Print-Optimized PDF — Enhanced invoice PDF template with company logo support
- IIF Import/Export — Full QuickBooks 2003 Pro interoperability (see below)
- Dark Mode — Toggle between QB2003 Blue theme and dark mode (Alt+D or toolbar button). Persists in localStorage
- Backup/Restore — Create and download PostgreSQL backups from the settings page
- Multi-Company — Support for multiple company databases, switchable from UI
- Global Search — Unified server-side search across customers, vendors, items, invoices, estimates, and payments
- Authentic QB2003 "Default Blue" skin with navy/gold color palette (+ dark mode)
- Splash screen with build info and decompilation provenance
- Windows XP-era toolbar, sidebar navigator with icons, status bar
- Keyboard shortcuts:
Alt+N(new invoice),Alt+P(payment),Alt+Q(quick entry),Alt+H(home),Alt+D(dark mode),Ctrl+S(save modal form),Ctrl+K(search),Escape(close modal) - No frameworks — vanilla HTML/CSS/JS single-page app
- 25 SPA routes, 24 sidebar nav links
- IIF Export — Export all Slowbooks data (accounts, customers, vendors, items, invoices, payments, estimates) as .iif files importable into QB2003 via File > Utilities > Import > IIF Files
- IIF Import — Parse and import .iif files exported from QB2003 with duplicate detection and per-row error handling
- Validation — Pre-flight validation of .iif files before import (checks structure, account types, balanced transactions)
- Date Range Filtering — Export invoices and payments for specific date ranges
- Round-Trip Safe — Export from Slowbooks, re-import into Slowbooks — deduplication prevents double-entry
- Backup Script —
scripts/backup.sh— pg_dump with gzip compression, keeps last 30 backups - Recurring Invoice Cron —
scripts/run_recurring.py— Standalone script for generating due recurring invoices - IRS Mock Data —
scripts/seed_irs_mock_data.py— Seeds realistic test data from IRS Publication 583 (Henry Brown's Auto Body Shop: 8 customers, 13 vendors, 10 invoices, 5 payments, 3 estimates)
| Component | Technology |
|---|---|
| Backend | Python 3.12 + FastAPI (31 routers, 144+ routes) |
| Database | PostgreSQL 16 + SQLAlchemy 2.0 |
| Migrations | Alembic |
| Frontend | Vanilla HTML/CSS/JS (no framework) |
| WeasyPrint 60.2 + Jinja2 | |
| Bank Import | ofxparse (OFX/QFX) |
| Payments | Stripe Checkout (hosted) |
| QBO Sync | python-quickbooks + intuit-oauth (OAuth 2.0) |
| Port | 3001 |
git clone https://github.com/VonHoltenCodes/SlowBooks-Pro-2026.git
cd SlowBooks-Pro-2026
docker compose upOpen http://localhost:3001. That's it — PostgreSQL, migrations, and seed data are handled automatically.
git clone https://github.com/VonHoltenCodes/SlowBooks-Pro-2026.git
cd SlowBooks-Pro-2026
pip install -r requirements.txt
# Create database
sudo -u postgres psql -c "CREATE USER bookkeeper WITH PASSWORD 'bookkeeper'"
sudo -u postgres psql -c "CREATE DATABASE bookkeeper OWNER bookkeeper"
cp .env.example .env
alembic upgrade head
python3 scripts/seed_database.py
python3 run.pyOpen http://localhost:3001.
See INSTALL.md for detailed instructions, macOS native install, demo data, and troubleshooting.
./scripts/backup.sh
# Backs up to ~/bookkeeper-backups/ with gzip compression
# Keeps the 30 most recent backupsSlowBooks-Pro-2026/
├── .env.example # Environment config template
├── requirements.txt # Python dependencies (14 packages)
├── run.py # Uvicorn entry point (port 3001)
├── alembic.ini # Alembic config
├── alembic/ # Database migrations
├── app/
│ ├── main.py # FastAPI app + 28 routers (132 routes)
│ ├── config.py # Environment-based settings
│ ├── database.py # SQLAlchemy engine + session
│ ├── models/ # 30+ SQLAlchemy models
│ │ ├── accounts.py # Chart of Accounts (self-referencing)
│ │ ├── contacts.py # Customers + Vendors
│ │ ├── items.py # Products, services, materials, labor
│ │ ├── invoices.py # Invoices + line items
│ │ ├── estimates.py # Estimates + line items
│ │ ├── payments.py # Payments + allocations
│ │ ├── transactions.py # Journal entries (double-entry core)
│ │ ├── banking.py # Bank accounts, transactions, reconciliations
│ │ ├── settings.py # Key-value company settings
│ │ ├── audit.py # Audit log
│ │ ├── purchase_orders.py # Purchase orders + lines
│ │ ├── bills.py # Bills + lines + payments + allocations
│ │ ├── credit_memos.py # Credit memos + lines + applications
│ │ ├── recurring.py # Recurring invoices + lines
│ │ ├── email_log.py # Email delivery log
│ │ ├── tax.py # Tax category mappings
│ │ ├── backups.py # Backup records
│ │ ├── companies.py # Multi-company records
│ │ ├── payroll.py # Employees, pay runs, pay stubs
│ │ └── qbo_mapping.py # QBO ↔ Slowbooks ID mappings
│ ├── schemas/ # Pydantic request/response models
│ ├── routes/ # FastAPI routers (28 routers)
│ ├── services/
│ │ ├── accounting.py # Double-entry journal entry engine
│ │ ├── audit.py # SQLAlchemy after_flush audit hooks
│ │ ├── closing_date.py # Closing date enforcement guard
│ │ ├── payroll_service.py # Withholding calculations
│ │ ├── recurring_service.py # Recurring invoice generation
│ │ ├── email_service.py # SMTP email delivery
│ │ ├── csv_export.py # CSV export (5 entity types)
│ │ ├── csv_import.py # CSV import with error handling
│ │ ├── ofx_import.py # OFX/QFX bank feed parser
│ │ ├── tax_export.py # Schedule C data + CSV export
│ │ ├── backup_service.py # pg_dump/pg_restore wrapper
│ │ ├── company_service.py # Multi-company DB management
│ │ ├── iif_export.py # IIF export (8 export functions)
│ │ ├── iif_import.py # IIF parser + import + validation
│ │ ├── pdf_service.py # WeasyPrint PDF generation
│ │ ├── stripe_service.py # Stripe Checkout + webhook verification
│ │ ├── qbo_service.py # QBO OAuth + token management + client factory
│ │ ├── qbo_import.py # Import 6 entity types from QBO
│ │ └── qbo_export.py # Export 6 entity types to QBO
│ ├── templates/ # Jinja2 templates (PDF, email)
│ ├── seed/ # Chart of Accounts seed data
│ └── static/
│ ├── css/
│ │ ├── style.css # QB2003 "Default Blue" skin
│ │ └── dark.css # Dark mode CSS overrides
│ └── js/ # SPA router, API wrapper, 23 page modules
├── scripts/
│ ├── seed_database.py # Seed the Chart of Accounts
│ ├── seed_irs_mock_data.py # IRS Pub 583 mock data
│ ├── run_recurring.py # Cron script for recurring invoices
│ └── backup.sh # PostgreSQL backup with rotation
├── screenshots/ # README images
└── index.html # SPA shell (23 script tags)
36 tables with a double-entry accounting foundation:
| Table | Purpose |
|---|---|
accounts |
Chart of Accounts — asset, liability, equity, income, expense, COGS |
customers |
Customer contacts with billing/shipping addresses |
vendors |
Vendor contacts |
items |
Product/service/material/labor items with rates |
invoices |
Invoice headers with status tracking |
invoice_lines |
Invoice line items |
estimates |
Estimate headers |
estimate_lines |
Estimate line items |
payments |
Payment records |
payment_allocations |
Maps payments to invoices (many-to-many) |
transactions |
Journal entry headers |
transaction_lines |
Journal entry splits (debit OR credit) |
bank_accounts |
Bank accounts linked to COA |
bank_transactions |
Bank register entries (with OFX import fields) |
reconciliations |
Bank reconciliation sessions |
settings |
Company settings key-value store |
audit_log |
Automatic change tracking for all entities |
purchase_orders |
Purchase order headers |
purchase_order_lines |
PO line items with received quantities |
bills |
Vendor bills (AP mirror of invoices) |
bill_lines |
Bill line items with expense account tracking |
bill_payments |
Bill payment records |
bill_payment_allocations |
Maps bill payments to bills |
credit_memos |
Customer credit memos |
credit_memo_lines |
Credit memo line items |
credit_applications |
Maps credit memos to invoices |
recurring_invoices |
Recurring invoice templates |
recurring_invoice_lines |
Recurring invoice line items |
email_log |
Email delivery history |
tax_category_mappings |
Account-to-tax-line mappings for Schedule C |
backups |
Backup file records |
companies |
Multi-company database list |
employees |
Employee records for payroll |
pay_runs |
Pay run headers with totals |
pay_stubs |
Individual pay stubs with withholding breakdowns |
qbo_mappings |
QBO ID ↔ Slowbooks ID mapping for sync deduplication |
All endpoints under /api/. Swagger docs at /docs. 132 routes across 28 routers.
| Endpoint | Methods | Description |
|---|---|---|
/api/dashboard |
GET | Company snapshot stats |
/api/dashboard/charts |
GET | AR aging buckets + monthly revenue trend |
/api/settings |
GET, PUT | Company settings |
/api/settings/test-email |
POST | Send SMTP test email |
/api/search |
GET | Unified search across all entities |
/api/accounts |
GET, POST, PUT, DELETE | Chart of Accounts CRUD |
/api/customers |
GET, POST, PUT, DELETE | Customer management |
/api/vendors |
GET, POST, PUT, DELETE | Vendor management |
/api/items |
GET, POST, PUT, DELETE | Items & services |
/api/invoices |
GET, POST, PUT | Invoice CRUD with line items |
/api/invoices/{id}/pdf |
GET | Generate invoice PDF |
/api/invoices/{id}/void |
POST | Void with reversing journal entry |
/api/invoices/{id}/send |
POST | Mark invoice as sent |
/api/invoices/{id}/email |
POST | Email invoice as PDF attachment |
/api/invoices/{id}/duplicate |
POST | Duplicate invoice as new draft |
/api/estimates |
GET, POST, PUT | Estimate CRUD with line items |
/api/estimates/{id}/convert |
POST | Convert estimate to invoice |
/api/payments |
GET, POST | Record payments with invoice allocation |
/api/banking/accounts |
GET, POST, PUT | Bank account management |
/api/banking/transactions |
GET, POST | Bank register entries |
/api/banking/reconciliations |
GET, POST | Reconciliation sessions |
| Endpoint | Methods | Description |
|---|---|---|
/api/purchase-orders |
GET, POST, PUT | Purchase order CRUD |
/api/purchase-orders/{id}/convert-to-bill |
POST | Convert PO to bill |
/api/bills |
GET, POST, PUT | Bill CRUD with line items |
/api/bills/{id}/void |
POST | Void bill |
/api/bill-payments |
POST | Pay vendor bills with allocation |
/api/credit-memos |
GET, POST | Credit memo CRUD |
/api/credit-memos/{id}/apply |
POST | Apply credit to invoices |
| Endpoint | Methods | Description |
|---|---|---|
/api/recurring |
GET, POST, PUT, DELETE | Recurring invoice templates |
/api/recurring/generate |
POST | Generate due recurring invoices |
/api/batch-payments |
POST | Batch payment application |
| Endpoint | Methods | Description |
|---|---|---|
/api/employees |
GET, POST, PUT | Employee CRUD |
/api/payroll |
GET, POST | Pay run CRUD |
/api/payroll/{id}/process |
POST | Process pay run (creates journal entries) |
| Endpoint | Methods | Description |
|---|---|---|
/api/reports/profit-loss |
GET | P&L report |
/api/reports/balance-sheet |
GET | Balance sheet |
/api/reports/ar-aging |
GET | Accounts receivable aging |
/api/reports/ap-aging |
GET | Accounts payable aging |
/api/reports/sales-tax |
GET | Sales tax collected |
/api/reports/general-ledger |
GET | All journal entries by account |
/api/reports/income-by-customer |
GET | Sales totals per customer |
/api/tax/schedule-c |
GET | Schedule C data from P&L |
/api/tax/schedule-c/csv |
GET | Schedule C CSV export |
| Endpoint | Methods | Description |
|---|---|---|
/api/iif/export/all |
GET | Export everything as .iif |
/api/iif/import |
POST | Import .iif file |
/api/csv/export/{type} |
GET | Export entities as CSV |
/api/csv/import/{type} |
POST | Import CSV file |
/api/bank-import/preview |
POST | Preview OFX/QFX transactions |
/api/bank-import/import/{id} |
POST | Import OFX/QFX into bank account |
| Endpoint | Methods | Description |
|---|---|---|
/api/qbo/auth-url |
GET | Generate Intuit OAuth authorization URL |
/api/qbo/callback |
GET | OAuth redirect handler (stores tokens) |
/api/qbo/disconnect |
POST | Clear stored QBO tokens |
/api/qbo/status |
GET | Connection status (never returns raw tokens) |
/api/qbo/import |
POST | Import all entity types from QBO |
/api/qbo/import/{entity} |
POST | Import single entity type |
/api/qbo/export |
POST | Export all entity types to QBO |
/api/qbo/export/{entity} |
POST | Export single entity type |
| Endpoint | Methods | Description |
|---|---|---|
/pay/{token} |
GET | Public payment page (no auth) |
/api/stripe/create-checkout-session |
POST | Create Stripe Checkout session |
/api/stripe/webhook |
POST | Stripe webhook handler |
/api/stripe/payment-link/{id} |
GET | Get public payment URL for invoice |
| Endpoint | Methods | Description |
|---|---|---|
/api/audit |
GET | Audit log viewer |
/api/backups |
GET, POST | Backup management |
/api/backups/{id}/download |
GET | Download backup file |
/api/companies |
GET, POST | Multi-company management |
/api/uploads/logo |
POST | Upload company logo |
Slowbooks can exchange data with QuickBooks 2003 Pro via Intuit Interchange Format (IIF) — a tab-delimited text format that QB2003 uses for file-based import/export.
- Navigate to QuickBooks Interop in the sidebar
- Click Export All Data (or export individual sections)
- For invoices/payments, optionally set a date range
- Save the
.iiffile - In QuickBooks 2003: File > Utilities > Import > IIF Files and select the file
What gets exported:
| Section | IIF Header | Fields |
|---|---|---|
| Chart of Accounts | !ACCNT |
Name, type (BANK/AR/AP/INC/EXP/EQUITY/COGS/etc.), number, description |
| Customers | !CUST |
Name, company, address, phone, email, terms, tax ID |
| Vendors | !VEND |
Name, address, phone, email, terms, tax ID |
| Items | !INVITEM |
Name, type (SERV/PART/OTHC), description, rate, income account |
| Invoices | !TRNS/!SPL |
Customer, date, line items, amounts, tax, terms |
| Payments | !TRNS/!SPL |
Customer, date, amount, deposit account, invoice allocation |
| Estimates | !TRNS/!SPL |
Customer, date, line items (non-posting) |
- In QuickBooks 2003: File > Utilities > Export > Lists to IIF Files
- In Slowbooks: navigate to QuickBooks Interop
- Drag and drop the
.iiffile (or click to browse) - Click Validate — checks structure, account types, and balanced transactions
- If validation passes, click Import
The importer handles:
- Automatic account type mapping (QB's 14 types → Slowbooks' 6 types)
- Parent:Child colon-separated account names
- Duplicate detection (skips records that already exist by name or document number)
- Per-row error collection (a bad row won't abort the entire import)
- Windows-1252 and UTF-8 encoded files
IIF is tab-delimited with \r\n line endings. Header rows start with !. Transaction blocks use TRNS/SPL/ENDTRNS grouping. Sign convention: TRNS amount is positive (debit), SPL amounts are negative (credits), and they must sum to zero.
!TRNS TRNSTYPE DATE ACCNT NAME AMOUNT DOCNUM
!SPL TRNSTYPE DATE ACCNT NAME AMOUNT DOCNUM
!ENDTRNS
TRNS INVOICE 01/15/2026 Accounts Receivable John E. Marks 444.96 2001
SPL INVOICE 01/15/2026 Service Income John E. Marks -438.00 2001
SPL INVOICE 01/15/2026 Sales Tax Payable John E. Marks -6.96 2001
ENDTRNS
| Slowbooks Type | IIF Types (by account number range) |
|---|---|
| Asset | BANK (1000-1099), AR (1100), OCASSET (1101-1499), FIXASSET (1500-1999) |
| Liability | AP (2000), OCLIAB (2001-2499), LTLIAB (2500+) |
| Equity | EQUITY |
| Income | INC |
| Expense | EXP |
| COGS | COGS |
The scripts/seed_irs_mock_data.py script populates Slowbooks with test data from IRS Publication 583 (Rev. December 2024) — "Starting a Business and Keeping Records." The sample business is Henry Brown's Auto Body Shop, a sole proprietorship with:
- 8 customers (John E. Marks, Patricia Davis, Robert Garcia, Thompson & Sons, etc.)
- 13 vendors from the IRS check disbursements journal (Auto Parts Inc., ABC Auto Paint, Baker's Fender Co., etc.)
- 8 service/material items (Body Repair, Paint & Finish, Dent Removal, Frame Alignment, etc.)
- 10 invoices totaling $3,631.31 with 1.59% sales tax
- 5 payments totaling $1,498.00
- 3 pending estimates
- All with proper double-entry journal entries
python3 scripts/seed_irs_mock_data.pySource Available — Free for personal and enterprise use. No commercial resale.
You can use, modify, and run Slowbooks Pro for any personal, educational, or internal business purpose. You cannot sell it or offer it as a paid service. See LICENSE for full terms.
- 14 years of QuickBooks 2003 Pro (1 license, $199.95, 2003 dollars)
- IDA Pro and the reverse engineering community
- The Pervasive PSQL documentation that nobody else has read since 2005
- Every small business owner who lost software they paid for when activation servers died
- VonHoltenCodes — Creator
- jake-378 — Backup UI fixes, report period selectors, invoice terms autofill, date validation fixes
Built by VonHoltenCodes with Claude Code.