Open Source Payroll Software
Payroll is the rare back-office system where a mistake is public the same week it happens: a wrong withholding or a missed filing lands on an employee's payslip and a regulator's desk at once, and the rules shift by jurisdiction every year. Most open source options in this space are really HR suites that carry a payroll module rather than dedicated payroll engines, so the first thing to establish is whether you are buying a rules engine or a whole HR system. Running it yourself keeps salary, tax, and bank details, some of the most sensitive records you hold, on your own infrastructure, and lets you read and adjust exactly how gross becomes net instead of trusting a closed calculation.
Frappe HR
Open source HR and payroll software for employee lifecycle, leave, attendance, and payroll management
Horilla
Open source HRMS for recruitment, attendance, leave, payroll, and employee management
OrangeHRM
Free, open source HR management system covering the essential HRM functions for any organization
NotrinosERP
Web-based open source ERP for accounting, CRM, inventory, manufacturing, payroll, and approvals
OCA Payroll
Odoo payroll modules for employee payroll records, accounting, and contract advantages
Payroll Engine
Open-source, regulation-driven framework for building payroll applications
Our picks
Pick by whether you need a calculation engine or a full HR system around it.
Best for jurisdiction-driven payroll: Payroll Engine Payroll Engine treats payroll logic as data: cases, wage types, and rules live in regulation layers that stack from base to country to industry to company and override per tenant. Time-stamped cases drive continuous runs with automatic retrospective recalculation. Built in C# on .NET with a REST API and Docker stack, it targets pay across jurisdictions.
Best all-in-one HR and payroll: Frappe HR Frappe HR is a full HRMS covering onboarding, leave, attendance, and exit, with payroll built in through salary structures, tax slabs, and off-cycle payments. Multi-level approvals gate sensitive changes, and a mobile app handles leave and check-in. It self-hosts with Docker or runs on managed Frappe Cloud.
Best self-hosted full HRMS: Horilla Horilla brings recruitment, attendance, leave, payroll, and performance into one self-hosted system on Python, Django, and PostgreSQL. It installs on Ubuntu, Windows, or macOS or from an official Docker image, seeding a company and departments on first launch. Maintained by Cybrosys Technologies, it keeps HR and payroll data on your own infrastructure.
Best for existing Odoo deployments: OCA Payroll OCA Payroll adds payroll to an Odoo instance you already run rather than a separate system to bolt on. It ships modules for payroll records, posting entries to accounting, contract advantages, and public-holiday integration. Maintained by the Odoo Community Association under AGPL, it fits shops whose accounting and HR already live in Odoo.
Knowing whether you need a payroll engine or an HR suite
The label 'payroll software' hides two very different products in this list. Payroll Engine is a framework whose whole premise is that payroll rules should live in configurable regulation layers rather than in code, which suits vendors and service providers processing pay across countries and industries. OCA Payroll is a set of Odoo addons for organizations that already run Odoo and want pay handled inside it. The rest, Frappe HR, Horilla, OrangeHRM, and the NotrinosERP suite, are HR or ERP systems where payroll is one module among leave, attendance, and onboarding. If you mainly need correct calculations across shifting tax rules, an engine fits; if you need the surrounding employee records too, a suite does.
Whichever type you choose, judge it on the payroll mechanics that break in production. Real payroll needs effective dates, retroactive corrections after a run has closed, rounding rules, garnishments, and year-end reporting, not a flat percentage table. Payroll Engine models input as time-stamped cases with validity periods and recalculates past runs automatically, which is exactly the behavior a simple template misses. For suite-based tools, confirm that salary structures, tax handling, and off-cycle payments match your pay frequencies before you trust a live run.
Treat access control and the exit path as payroll-specific requirements. Because these records include salaries, tax identifiers, and bank details, look for role-based permissions and approval steps so the person editing pay rates is not the only one approving the run; NotrinosERP and Frappe HR both build multi-level approvals in. Confirm you can export employee master data, pay history, and journal entries in plain formats, since payroll migrations are painful when history is trapped in screens.
Related categories
Frequently asked questions
Is this open source payroll software, or HR software with payroll added?+
Both, and it matters. Payroll Engine and OCA Payroll are payroll-first: a rules engine and a set of Odoo pay modules. Frappe HR, Horilla, OrangeHRM, and NotrinosERP are broader HR or ERP systems where payroll is one module beside leave, attendance, and onboarding. If you only need a calculation engine, a suite adds overhead you will not use; if you need employee records too, a dedicated engine leaves gaps you must fill elsewhere.
Who is responsible if the tax calculations are wrong?+
Your organization, not the software. A tool can provide a rules engine or tax logic, but you must confirm it matches your jurisdiction, pay schedule, employee classifications, and effective dates. Payroll Engine makes its rules configurable and inspectable, which helps you verify them, but it does not remove the obligation. For anything complex, have a payroll specialist review the setup and run test cases before money moves.
Can open source payroll handle multiple states or countries?+
Some can, but check the details rather than the claim. Multi-state pay needs local taxes, reciprocal rules, and work-location reporting; multi-country adds currencies, tax calendars, and statutory filings. Payroll Engine is built for exactly this, stacking base, country, industry, and company rules per tenant. Suite-based tools vary widely, so if you operate across jurisdictions, confirm the specific rules are modeled before assuming growth is just configuration.
Will these generate bank files for direct deposit?+
Do not assume it. Banks often require a specific file format, field layout, and transmission method, and many of these tools export accounting entries or CSV rather than a ready bank file. Confirm whether your chosen tool produces the format your bank accepts, or whether you need a separate step to convert its output. Test a validation or prenote run before you fund a real payroll from it.
How should permissions be set for a payroll team?+
Use separation of duties. The person who edits pay rates or bank accounts should not be the only one who approves the final run. NotrinosERP offers role-based access with multi-level approval workflows, and Frappe HR includes multi-level approvals, which lets you gate sensitive changes. Look for change history around rates and bank details, and keep salary visibility away from roles that only need time approvals.
How do we move off our current payroll provider?+
Export employee profiles, pay rates, tax elections, deductions, leave balances, and year-to-date wages, then map every earning and deduction code to the new system. Expect cleanup around inactive employees and inconsistent addresses. Before switching, run at least one parallel payroll and reconcile gross pay, taxes, deductions, net pay, and accounting entries line by line. Do not go live until every difference is explained rather than accepted.
What happens if a payroll project loses its maintainer?+
The immediate risk is not losing the code; it is losing tax-table updates and security fixes before the next compliance change. Reduce it by choosing tools with readable code, documented schemas, and standard database storage so history stays exportable; Payroll Engine keeps rules in configurable layers you control, and the suites here run on ordinary SQL databases. Keep internal runbooks for setup and closing so another team or vendor can take over.