Odoo

Odoo is an open-source business suite that bundles CRM, sales, invoicing, accounting, inventory and e-commerce into one database. Apps can be added for manufacturing, helpdesk, subscriptions, projects and human resources, and each module shares the same records, so a quote becomes an invoice without retyping anything.

Small businesses and operations teams use it to run the company rather than glue together separate tools, and it can be configured to suit your workflow.

Hosting it yourself keeps customer and financial data under your control, avoids per-module SaaS pricing, and a database backup puts the whole operation back the way it was.