Frappe
Define a DocType in Frappe and the framework automatically generates database tables, Python ORM classes, REST API endpoints, form views, list views, and role-based permission rules from that single schema definition. The meta-driven architecture stores schemas as database records, letting administrators add fields, reorder layouts, and modify validation rules through the browser-based Form Builder without redeployment. Server-side Python controllers handle business logic through hook-based lifecycle events while client-side JavaScript manages interactive form behavior, with WebSocket connections providing real-time updates across sessions. The built-in workflow engine defines document state machines with role-gated transitions, email notifications, and conditional action visibility. Pre-configured Desk views include list, form, report, tree, kanban, calendar, and dashboard layouts with drag-and-drop workspace customization. The report builder generates grid reports with configurable columns, filters, grouping, and chart visualizations from DocType data or custom SQL and Python scripts. Background job processing uses Redis queues for email delivery, data imports, and periodic tasks. Virtual DocTypes connect external databases to the framework's UI without data migration. Docker deployment via frappe_docker provides production-ready Compose configurations with MariaDB, Redis, Nginx, and worker containers. The foundation powering ERPNext, HRMS, CRM, and Helpdesk in production. Over 10,500 GitHub stars. MIT licensed.
REI3
Replace the spreadsheet that quietly runs your department with a proper multi-user application that you design in a browser with REI3, a self-hosted low-code platform. Authors define their data model once, then assemble forms, lists, calendars, Gantt plans, Kanban boards, and charts around it, with form states that show, hide, or require inputs as a record moves through its workflow. Calendars create records from a drag-selected time range, Kanban cards change state by drag and drop, and bulk-update forms edit hundreds of records at once. Phones scan barcodes and QR codes through the camera, and signature pads capture drawings. Roles and record-level access policies decide who sees what, sign-in runs through LDAP, OpenID Connect, or multi-factor authentication, and end-to-end encryption keeps selected fields unreadable even to administrators. REST endpoints work in both directions, ICS feeds publish calendars, CSV moves data in bulk, and IMAP and SMTP accounts connect applications to email. A drag-and-drop PDF editor produces letterheads, labels, and documents with signatures and barcodes. More than a dozen free ready-made applications, including tickets, time tracking, IT assets, a password safe, and a CRM, install from the admin panel. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.