Curated list of the best free and open‑source AR/ invoicing tools that help small‑to‑mid‑size businesses manage invoices, payments, and customer credit without breaking the bank.
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Feature‑rich invoicing platform with recurring billing, payment gateway integrations, and client portal; community edition is fully open source.
Lightweight PHP application for creating, sending, and tracking invoices; supports multiple languages, PDF generation, and basic AR reporting.
Modular ERP/CRM suite with a dedicated invoicing module, payment reminders, and simple AR dashboards; community edition is GPL‑licensed.
Full‑stack ERP built on Frappe framework; includes comprehensive accounts receivable, multi‑currency invoicing, and automated payment reconciliation.
Open‑source ERP with an invoicing app that handles AR, payment follow‑ups, and integration with popular payment providers.
Online accounting software with invoicing, client management, and AR aging reports; built with Laravel and released under the MIT license.
PHP‑based invoicing system focused on ease of use; supports invoice templates, payment tracking, and basic AR aging.
Web‑based accounting system with invoicing, credit control, and AR reporting; suitable for small businesses seeking a lightweight solution.
Three‑tier, modular ERP platform; its invoicing module provides full AR lifecycle management, multi‑company support, and customizable workflows.
Complete web‑based ERP written in PHP; includes invoicing, credit control, and detailed AR aging reports.
Accounting and ERP system derived from SQL-Ledger; offers invoicing, payment processing, and AR aging with strong audit trails.
Standalone accounting app built on the Frappe framework; provides invoicing, payment reminders, and AR analytics.
Java‑based ERP with an invoicing module that handles AR, credit limits, and automated reminders; community edition is open source.
While primarily a time‑tracking tool, Kimai’s billing plugin adds invoice creation and AR tracking for service‑based firms.
An optional module for Dolibarr that syncs online orders with invoicing, enabling automated AR entry from e‑commerce platforms.
Pre‑packaged Docker deployment of Invoice Ninja Community; simplifies self‑hosting for teams with limited IT resources.
Open‑source core banking platform with loan and savings modules; includes receivable management for micro‑finance institutions.
Standalone accounting add‑on for Odoo Community that focuses on AR, payment follow‑ups, and reconciliation without needing the full ERP suite.
Minimalist Java‑based invoicing system with AR aging, PDF export, and email reminders; ideal for startups seeking a lightweight solution.
Asset management tool that can generate invoices for asset rentals; with the billing extension it tracks receivables linked to assets.