Open Source ERP Software
An ERP is the system every other tool in a company eventually has to agree with: accounting, inventory, payroll, and sales all post into one ledger of record, which is why migrating off one is so brutal and why the data model deserves more scrutiny than the feature grid. What actually decides fit is whether the software already encodes how your orders become invoices, how stock valuation hits the ledger, and how your country's tax and payroll rules work, because those are painful to bolt on later. The open source ERPs here put that schema and business logic in front of you, so you can adapt workflows to how the company really runs and keep years of accumulated records in a database you control rather than a vendor's.
Odoo CRM
Open source CRM for managing prospects and customers inside Odoo's web based business apps
ERPNext
Open source ERP for accounting, inventory, orders, manufacturing, assets, projects, and daily operations
Aureus ERP
Laravel and Filament ERP for sales, accounting, inventory, HR, CRM, and projects
IDURAR
Self-hosted ERP and CRM for invoicing, quotes, accounting, inventory, and HR
Dolibarr
Web-based ERP and CRM for managing quotes, invoices, orders, stocks, accounting, and more
Ever Gauzy
Business management platform combining ERP, CRM, HRM, ATS, project work, and employee time tracking
metasfresh
Free and open source ERP for industry and trade, with sales orders, invoicing, and a REST API
Apache OFBiz
Java ERP system for automating enterprise processes, with apps for commerce, CRM, supply chain, and manufacturing
Axelor Open Suite
Full-web ERP suite with modular apps for CRM, finance, HR, projects, inventory, and production
Our picks
Start from how broad your needs are and how much you expect to customize.
Broadest all-in-one suite: ERPNext ERPNext covers accounting, inventory, sales orders, manufacturing, assets, and projects in one system. It runs on the Frappe Framework with a REST API, and you can self-host with Docker or use Frappe Cloud. A strong default when you want most of the business in one open, well-rounded ERP rather than stitched-together apps.
Approachable for small businesses: Dolibarr Dolibarr manages contacts, quotes, invoices, orders, stock, accounting, and HR from one web app, with around 100 modules you enable as needed. Written in PHP over MariaDB, MySQL, or PostgreSQL, it installs easily and offers REST and SOAP APIs. It suits freelancers, foundations, and small companies that want ERP and CRM without a heavy implementation.
Customizable, with mature business logic: iDempiere iDempiere is an ERP, CRM, and supply-chain suite whose logic descends from ADempiere and Compiere and has been refined over years of real use. Its OSGi plugin system extends and customizes functionality without touching the core, and it runs on PostgreSQL or Oracle with accounting, manufacturing, and point-of-sale modules. Built for teams that expect to adapt the system deeply.
For industry and trade: metasfresh metasfresh targets industry and trade with sales orders, shipments, and invoicing on a three-tier architecture and a REST API. Its web frontend is built with ReactJS and Redux over a PostgreSQL backend, and a stable release ships almost every Friday. A fit for teams wanting an in-house ERP with frequent updates and full control.
Judging an ERP by process fit, not the feature grid
Process fit beats feature count, because an ERP encodes decisions: how orders become invoices, how inventory valuation posts to the ledger, how approvals move, and how period close works. A system that already matches your chart of accounts, tax rules, and costing method will beat a broader one that needs heavy surgery, and accounting and payroll localization is the part that is hardest to patch later. If manufacturing drives your business, validate bills of materials, work orders, and costing end to end; ERPNext and Apache OFBiz carry deep manufacturing and supply-chain logic, while Dolibarr and IDURAR are lighter and aimed more at services, invoicing, and CRM.
Decide up front how much of the core you are willing to change. An ERP becomes the system of record for customers, suppliers, products, journals, and employees, so small custom fields are routine but rewriting posting logic or stock moves is a long-term commitment. Favor clear extension points and a way to keep custom code separate from vendor code: iDempiere uses an OSGi plugin system, Tryton and Odoo are modular by design, and Aureus ERP installs features as plugins through Artisan commands. If every upgrade means manual conflict resolution, the license savings turn into a maintenance burden.
Treat deployment, integration, and exit as one decision. Self-hosting gives you database access and network control but hands you backups, monitoring, job queues, and upgrade rehearsals; managed options like Frappe Cloud for ERPNext or the hosted editions of Dolibarr and IDURAR reduce that load but may limit database-level access. Map every integration before rollout - bank feeds, tax services, ecommerce, payroll, and identity - and confirm you can export master data, journal entries, and audit trails in usable formats well before the day you need to leave.
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Frequently asked questions
Do I need a full ERP, or would separate accounting, CRM, and inventory tools do?+
The point of an ERP is one shared database, so a sale, a stock movement, and a journal entry stay consistent instead of being reconciled across tools. Separate best-of-breed apps can be simpler, but every integration becomes a place where numbers drift. Suites here range from broad, like Odoo, ERPNext, Dolibarr, and iDempiere, to focused, like IDURAR for invoicing and CRM or Ever Gauzy for services and time tracking. Choose a full ERP when finance and operations must always agree.
Will an open source ERP handle accounting and tax compliance in my country?+
Verify this early, because accounting localization covers tax calculation, invoice formats, fiscal calendars, statutory reports, and payroll rules. Some systems cover common jurisdictions well and leave others to partners or custom modules; Dolibarr and ERPNext have broad community localizations, but coverage varies by country. Have a local accountant review the posting model and required reports against a real trial before you commit, rather than trusting a generic compliance claim.
How hard is it to migrate from spreadsheets or an older ERP?+
Migration effort tracks data quality more than row count. Customers, vendors, products, units of measure, opening balances, unpaid invoices, and inventory quantities all need reconciliation, and most teams move master data and open transactions while keeping historical detail in read-only archives. Plan at least one test migration and a finance sign-off before cutover, and keep the old system available until the new numbers are trusted.
What should a manufacturer check before choosing?+
Test the production flow with real products, not a demo. Bills of materials, routings, work orders, scrap, subcontracting, lot tracking, and costing should reflect how your shop actually plans and records work. ERPNext and Apache OFBiz carry manufacturing and supply-chain modules, and iDempiere and ADempiere include manufacturing alongside ERP and CRM. If you rely on finite scheduling or complex traceability, pilot those exceptions before accepting a generic manufacturing screen.
How much customization is safe before upgrades become painful?+
Custom reports, fields, approval rules, and integration adapters are usually safe. Rewriting accounting postings, inventory valuation, or core order flows is where upgrades and audits get hard. Keep custom code isolated and documented: iDempiere's OSGi plugins, the modular Tryton and Odoo apps, and Aureus ERP's plugin model all exist to keep your changes separate from vendor code. If a requirement forces deep changes, first ask whether the business process can move instead.
How do permissions work for finance and operations teams?+
ERP permissions need more than admin and user roles. You often need separation between creating an invoice and approving its payment, warehouse users limited by location, and managers who can approve but not alter accounting entries. Look for role-based controls, record rules, approval workflows, and audit logs, and test sensitive tasks with real user profiles before rollout. Weak separation of duties is a finding auditors care about, so design it deliberately.
What happens if the ERP project slows down or stops?+
Because the code is open, you can keep running an ERP even if its project slows, but security fixes, tax-rule updates, and compatibility work may become your responsibility. Lower that risk by choosing a system with an understandable architecture and more than one service provider behind it, and by keeping clean exports of master data, journal entries, and audit trails plus documentation of your customizations. A current test environment makes it possible to patch or fork without reverse-engineering the whole repository.