7 Best Open Source Invoice Software Picks

Invoice Ninja covers the core billing cycle in one place, with invoices, quotes, recurring billing, expenses, time tracking, projects, and a client portal. The vendor pricing page lists 11 invoice templates on every plan, plus deposits and partial payments, online payment gateways, and connections to Zapier, Make, and n8n. That combination makes it useful for a freelancer who sends repeat work to the same clients and wants clients to view and pay invoices through a portal, without moving to a full accounting system at the start.

• The Free plan costs $0 and covers up to 5 clients with unlimited invoicing.
• Ninja Pro costs $14 per month billed monthly, or $140 billed annually, and adds unlimited clients, removal of Invoice Ninja branding, a branded portal
• Enterprise starts at $18 per month for 1 to 2 users and rises to $300 per month for 51 to 100 users, and adds user permissions, bank account sync, e-i

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Akaunting is accounting software with invoicing at its centre, so it suits a small business that wants invoices, bills, expenses, banking, and reports in the same system. The vendor plans page lists invoicing, expense tracking, cash flow, transaction categories, and payments, plus multiple currencies and unlimited customers, vendors, reports, and products or services on Cloud plans. Premium Cloud adds double-entry accounting, bank feeds, expense claims, roles and permissions, and a client portal, while Elite Cloud adds estimates, payroll, projects, inventory, CRM, receipts, Shopify, and Stripe.

• The free route is the self-hosted Standard On-Premise plan, which the vendor lists as free for 1 company, 1 user plus 1 accountant, and 1,000 invoices
• Cloud Standard costs $12 per month billed monthly, or $8 per month billed yearly, for the same limits, plus 4 apps and ticket support.
• Premium Cloud costs $36 per month, Elite Cloud costs $84 per month, and Ultimate Cloud costs $218 per month.

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Dolibarr is an ERP and CRM suite rather than an invoicing app on its own, so it suits a team that wants invoices tied to contacts, products, stock, purchase orders, projects, and human resources. The modular design is the main point: you enable the invoice module and the other modules you need, and leave the rest switched off. That keeps the daily view closer to the work you actually do, while the same database still holds the customer, product, and payment records that sit behind each invoice.

• The software itself is free to download and self-host, and the hosted route is DoliCloud.
• DoliCloud Basic costs 14 euros per user per month and includes all official modules, 4 GB of storage, 2,000 API calls per month, email sending limited
• DoliCloud Premium costs 30 euros per month plus 15 euros per user per month, and raises storage to 20 GB and API calls to 20,000 per month, with prior

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InvoicePlane is the most focused tool in this list. Its homepage describes a complete billing circle, from quotes to invoices to payments, with client management, custom fields, basic project and task management, themes, amount formats, and email and PDF templates. From version 1.6.2, it supports the creation of eInvoices that can be compliant with the standards set by the European Union.

• Clients can pay online through providers such as PayPal and Stripe, and the interface is translated into many languages by community members.
• The appeal is the low cost and the narrow scope.
• There is no monthly charge for the software itself, and the MIT licence gives you freedom to download, use, and modify the code.
• The trade-off is that you take on hosting, installation, updates, backups, and email setup yourself, and you rely on community help when something goe

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ERPNext is a full ERP, so invoicing sits beside accounting, sales, procurement, stock, manufacturing, projects, point of sale, CRM, HR, and payroll. That breadth suits a business that has outgrown a single invoicing app and wants one database for orders, stock, invoices, and payments, without a per-user licence fee. The vendor pricing page states that ERPNext is free and open source, that there are no hidden features behind a paywall, and that the source code has been open source since 2009.

• The cost is hosting and implementation, not a licence.
• Frappe Cloud Sites start at $5 per month onwards for a single site on shared servers, with managed upgrades and backups.
• Server plans start at $20 per month onwards, and premium dedicated servers start at $125 per month onwards.
• The vendor offers a 14-day free trial on Frappe Cloud, and self-hosting is free under the GPL-3.0 licence.

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Odoo is a suite of business apps, and invoicing is one app inside that suite, alongside CRM, sales, accounting, inventory, purchase, project, HR, website, and point of sale. The One App Free plan is the entry point: it costs $0, covers one app with unlimited users, and runs on Odoo Online, with required dependent apps included free as well. That makes it possible to start with invoicing alone, then add apps as the business needs them, without changing the system or moving data to a new product.

• Standard costs $24.90 per user per month in the first year on annual billing, renewing at $31.10, with monthly billing at higher rates.
• Standard includes all apps on Odoo Online, plus hosting, daily backups, email integration, support by email, and upgrades.
• Custom costs $49.00 per user per month in the first year on annual billing, renewing at $61.00, and adds Odoo Studio, multi-company, the external API,

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Bigcapital is modern open source accounting and inventory software for small and medium businesses, with invoicing as part of a double-entry ledger. Capital Basic covers unlimited sale invoices and estimates, GST and VAT tracking, bank connections for automatic importing, chart of accounts, manual journals, and basic financial reports and insights. That gives a small business a clear link between each invoice, the bank transaction that settles it, and the reports that show what is owed and what has been received.

• Capital Basic costs $20 per month, Capital Essential costs $40 per month, Capital Plus costs $55 per month, and Capital Big costs $60 per month, with
• Essential adds purchase invoices, multi-currency transactions, transaction locking, inventory tracking, and smart financial reports.
• Plus adds custom user roles, vendor credits, budgeting, and cost centre analysis.
• Big adds multiple branches and multiple warehouses.

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