Stack Research

Lightweight, high-performance email marketing. Go + PostgreSQL. Full REST API, JSONB subscriber attributes, transactional email, bounce handling. Excellent AI controllability — Claude can fully operate it via API. Missing visual builder and advanced automation sequences, but does core email marketing very well. Average score: 8.5/10.

Full marketing automation. PHP/MariaDB. 123 DB tables. Massive API. Closest OSS to GHL. Heavy on resources but feature-rich. Avg score: 7.2/10.

Closest OSS equivalent to GHL. PHP/Apache + MariaDB, 139 tables covering full sales and marketing CRM: accounts, contacts, leads, opportunities, campaigns, mass email, target lists, lead capture, knowledge base, portals, calendaring, documents. REST API over everything with metadata editability, but no MCP/GraphQL and no built-in agent system. Avg score: 7.3/10.

Commercial target for comparison only. Not evaluated for installation.

Most feature-rich OSS CRM — rivals Salesforce breadth. 219 tables covering sales, marketing, quoting, invoicing, workflows, support, security groups, custom fields. V8 REST API (JSON:API, OAuth2) + legacy V4.1 API. But: heavy SugarCRM-derived architecture, OAuth2 setup friction, Bitnami image now on legacy channel (Broadcom uncertainty), no GraphQL/MCP, workflow design requires UI. Avg score: 6.3/10.

Best-in-class AI controllability for CRM. Node/NestJS + PostgreSQL + Redis + worker. Triple API (REST + GraphQL + MCP built-in). Metadata-driven schema, first-class agent/skill/webhook system. Heavier than EspoCRM but an order of magnitude more AI-operable than GHL. Avg score: 8.3/10.