Why Building Your Own Accounting Software Is Harder Than It Looks Chintan Prajapati February 23, 2026 4 min read introductionA Real Discovery Story: What We Learned After Reviewing 20+ Open-Source Accounting SystemsThe “Simple” Question That Wasn’t Simple at AllA large accounting firm reached out to us with an idea that sounded bold—but also very logical.They serve over 1,000 clients across different industries. Like most firms, they were paying per-client fees to tools like QuickBooks and Xero. Over time, that cost adds up.So they asked:“What if we build our own accounting software?”The vision was compelling: One firm-owned accounting platform Used by every client Built around their internal workflows Same standards, same processes, same reporting style Less dependency on third-party vendorsFrom a business point of view, it made sense.At first, we advised against it.Building a general-purpose accounting system that works across industries, tax regimes, compliance requirements, and reporting expectations is one of the most complex problems in business software. It demands deep accounting expertise, long-term engineering investment, and constant regulatory maintenance.Still, the firm wanted to explore the idea at least as a discovery exercise to understand whether this could be done cost-effectively.That discovery led us down a path most firms underestimate.The Discovery Goal: Cut Cost Without Rebuilding the WorldThe firm’s objective was not to reinvent accounting.It was to reduce long-term SaaS costs while retaining control.The hypothesis was simple: Use an existing open-source accounting system Customize it for firm workflows Offer it to clients under the firm’s brand Avoid recurring per-client SaaS fees If this worked, it could save millions over time.To test this, we evaluated more than 20 open-source accounting and ERP systems, narrowing them down to the most relevant candidates.The Reality We EncounteredOpen source is powerful but not designed for unrestricted commercial redistribution.Most systems fail not because of missing features, but because of: Architectural limitations for SaaS Licensing constraints around redistribution Tight coupling that prevents proprietary extensions Long-term legal and maintenance riskBelow are the most relevant systems we analyzed.GnuCash: Reliable, but Architecturally OutdatedGnuCash is one of the most mature open-source accounting tools available. It implements proper double-entry accounting and has stood the test of time.However, it is fundamentally: Desktop-oriented Not web-native Not designed for multi-tenant environmentsFrom a licensing perspective, GPLv2 does not prohibit SaaS hosting. But embedding or extending GnuCash into a modern, client-facing platform is impractical.GnuCash works well for individuals and very small businesses, not for a firm-wide platform serving hundreds or thousands of clients.Odoo Community Edition: The Most SaaS-Friendly OptionOdoo stood out immediately.It is: Web-based and modular Designed for extensibility Licensed under LGPLv3, which is SaaS-friendlyLegally, you can host Odoo as SaaS and build proprietary services on top of it. LGPL obligations apply mainly when modified core modules are redistributed.The trade-off is strategic rather than legal: Many advanced accounting features exist only in the Enterprise edition Long-term alignment with Odoo’s ecosystem becomes unavoidable It turns your accounting strategy into an ERP strategyOdoo is viable but only if you are comfortable building on top of Odoo, not just borrowing from it.View Odoo Licensing DocumentationERPNext: Powerful, but Strategically RiskyERPNext is modern, feature-rich, and cloud-ready. On paper, it looks like an ideal foundation.It is licensed under GPLv3.While GPLv3 does not legally prohibit SaaS hosting, the practical reality is more complex: Core modules are tightly coupled Proprietary extensions are difficult to isolate The ecosystem strongly favors open contribution Commercial redistribution introduces compliance complexityFor a firm seeking long-term proprietary control over its accounting IP, ERPNext introduces strategic and operational risk.View ERPNext LicenseFrontAccounting: Lightweight, but Not Built for ScaleFrontAccounting is simple, fast, and easy to deploy.However: The architecture is dated Extensibility is limited Multi-client SaaS scenarios are not first-classIt works well for internal use or small deployments. For a large accounting firm building a branded client platform, it would require extensive customization bringing licensing and maintenance challenges back into scope.Visit FrontAccounting WikiDolibarr: Flexible, but GPL-BoundDolibarr offers flexibility and modularity and is easier to customize than many older systems.However: GPLv3+ licensing complicates redistribution Enterprise-grade accounting depth is limited Heavy customization increases long-term riskDolibarr is a solid internal system, but not an ideal foundation for a firm-owned, client-facing accounting product.View Dolibarr License FAQLedgerSMB: Strong Core, Weak SaaS FitLedgerSMB has a robust accounting core and strong security controls.But: Setup and customization are complex Modularity is limited Proprietary extensions are hard to separate cleanlyWhile GPLv2 allows SaaS hosting, LedgerSMB is not designed for white-label or resale scenarios.View LedgerSMB License DocumentationAkaunting: Explicitly RestrictedAkaunting looks modern and SaaS-ready, but its Business Source License (BSL) explicitly restricts competing SaaS offerings.There is no ambiguity here: Public SaaS redistribution is not allowed A commercial license is mandatoryThis option was eliminated early.The Pattern We Couldn’t IgnoreAfter weeks of evaluation, a clear pattern emerged.There is no open-source accounting system that allows you to: Modify core logic freely Redistribute it to clients Charge for it as proprietary software Retain full control over roadmap and IPOpen source helped us learn faster, but it could not safely become the foundation.The Decision: Build the Accounting Engine YourselfThe conclusion was not what the firm initially hoped for, but it was clear.If an accounting firm wants to: Own its platform Control client experience Avoid licensing risk Protect long-term IPThe only defensible approach is to build a proprietary double-entry accounting engine, tailored to the firm’s workflows.Yes, this requires investment.But it also provides: Legal clarity Architectural freedom Long-term scalability No dependency surprisesA Practical Note for Accounting FirmsIf your firm is: Managing hundreds or thousands of clients Paying significant recurring SaaS fees Exploring a custom accounting platformStart with discovery, not development.We spent weeks analyzing this path, and it prevented a far more expensive mistake later.ConclusionBuilding accounting software is not just a technical challenge. It is a legal, architectural, and strategic commitment.Open source is an excellent learning tool, a great reference, and a powerful accelerator during discovery.But when it comes to owning and monetizing accounting software, shortcuts almost always surface later as constraints.The firms that succeed are not the ones who build faster, but the ones who decide carefully what is worth building at all.