What ERP is — definition, modules and implementation

ERP (Enterprise Resource Planning) is a software category that consolidates all operational processes of a company in a single database — from order entry, through production planning, warehouse management, invoicing, to accounting. Unlike CRM, which focuses on what will be sold, ERP manages what IS being sold and fulfilled.

Typical ERP modules include: order management (sales and purchasing), warehouse (stock levels, locations, stocktakes), production (BOM, work orders, schedules), finance and accounting (invoices, receivables, payables), HR and payroll, management reporting. In modular systems like Open Mercato each of these can be deployed independently and added as the company grows.

ERP makes sense when a company reaches a scale where separate Excel sheets and tools stop working. Typical signals: warehouse data doesn't match invoices, orders 'get lost' between teams, monthly reports require days of manual work, GDPR or tax audits expose gaps in logs. ERP solves these via a single 'source of truth' for the whole company.

ERP implementation is usually more complex than CRM — typically 3-9 months for SMEs, up to 18 months for larger organisations. This stems from integration with accounting systems, historical data migration and per-department process configuration. Implementation cost EUR 8,000-45,000 for SMEs in Europe, plus optional licences (EUR 0 for open source, tens of thousands for SAP/Dynamics).

Open source ERP (Open Mercato, Odoo, ERPNext) is gaining traction in SMEs because it offers full data control, no per-user fees and customisation for industry-specific processes (manufacturing, distribution, B2B commerce). For regulated businesses (finance, healthcare) open source additionally enables code audits and on-premise hosting.