2026-03-01 project open-source python cli invoicing pdf privacy-first

Invoice CRM

Free, open-source invoice generator for freelancers and small businesses. File-based, git-friendly, AI-agent compatible. No SaaS, no monthly fees.

The Problem

Freelancers and solo founders need invoicing but typical SaaS solutions cost $10-60/month, keep your data on their servers, and don’t work offline. They also don’t integrate with AI coding agents.

Solution

A Python CLI tool where all data (clients, providers, bank details) lives in YAML files on your machine. Professional PDF generation with Jinja2 templates, WeasyPrint rendering, and optional digital signatures.

Key Features

Invoice Generation — professional PDF invoices with automatic numbering
QR Payment Codes — EPC/SEPA (EUR), EMVCo (TRY), SWIFT text (USD), crypto addresses (USDT/BTC)
Digital Signatures — optional PDF signing with self-signed certificates
File Encryption — optional age encryption for sensitive files
Multiple Banks — support for multiple bank accounts per provider
Company Cards — bank details cards with payment QR codes
Letter Generation — business letters with customizable templates

Architecture

providers/*.yaml    → your companies (bank details, tax info)
clients/*.yaml      → your clients (address, defaults, rates)
templates/*.html    → Jinja2 + CSS templates
crm.py              → main CLI (click)
qr.py               → QR code generator
signing.py          → PDF digital signatures (pyHanko)
crypto.py           → age encryption
schemas.py          → Pydantic validation

Deterministic pipeline: YAML configs → Pydantic validation → Jinja2 rendering → WeasyPrint PDF → optional QR/signing/encryption.

AI-Agent Compatible

Works with Claude Code, Cursor, or any AI agent as a natural language interface:

Invoice ACME for 80 hours at $150
Generate bank details card for my company

Bank details never pass through the LLM — they come from deterministic config files. The agent only triggers the CLI with parameters.

Privacy Architecture

All data on your machine — no cloud, no accounts
Bank details in config files, never in LLM context
Optional encryption with age
Git-friendly — version control your invoicing history
Works fully offline

vs SaaS

Feature	Typical SaaS	Invoice CRM
Monthly cost	$10-60	Free
Data location	Their servers	Your machine
Offline	No	Yes
Version control	No	Git
AI integration	Limited	Full
Customization	Template picker	Full HTML/CSS

Stack

Python 3.11+, Click, Pydantic, Jinja2, WeasyPrint, pyHanko, age encryption, uv.