freescout

FreeScout is a self-hosted help desk and shared inbox that directly replaces Zendesk or Help Scout. The core gives you unlimited users, unlimited tickets, unlimited mailboxes, email integration, collision detection, auto-reply, internal notes, and a mobile-friendly interface. All free.

Runs on PHP 7.1+ with a standard web server. Lightweight by design, so it works on cheap VPS instances. Updates are handled through a built-in web updater. The base install is simple, but advanced features come through paid modules (lifetime licenses, not subscriptions).

Solo support reps and small teams get a complete help desk for free. Paid modules add things like Slack integration, knowledge base, tags, and LDAP. Each module is a one-time purchase, which keeps long-term costs low compared to per-seat SaaS pricing.

The catch: the module ecosystem is where they make money. The free core is genuinely useful, but you will likely want 3-5 paid modules to match what Zendesk includes by default. Budget $200-400 one-time for a fully equipped instance.