GRR

GRR is an open-source web application for managing and reserving shared resources such as rooms, equipment and vehicles. It is an adaptation of the MRBS PHP/SQL booking system and targets organisations that need calendar-style resource reservation and administration. (devome.com)

Key Features

• Browser-based resource and domain management (rooms, materials, vehicles) with per-resource settings.
• Create, modify and cancel reservations with support for recurring bookings and block operations.
• Fine-grained access control: domain/resource restrictions, role-based delegation, and moderated or provisional bookings.
• Multiple calendar views and domain-specific display/customisation (working hours, slot granularity, visual presentation per domain).
• Automated email notifications and configurable mail templates for reservation lifecycle events.
• Maintenance/availability flags and the ability to mark reservations as "in use" or temporarily disable resources.
• External integrations and authentication: LDAP, SSO, IMAP and Azure AD configuration supported.
• Internationalisation and UTF-8 compatibility; domain-level additional fields and presentation images for resources. (devome.com)

Use Cases

• Centralised room and equipment booking for universities, municipalities, and enterprises that need multi-domain calendars and delegated administration.
• Shared asset scheduling for project sites or construction teams needing reservation approvals, moderation, and block/periodic bookings.
• Small organisations seeking a lightweight, self-hosted shared calendar/reservation system integrated with existing LDAP/SSO infrastructure.

Limitations and Considerations

• Requires a LAMP-like environment (PHP 8.1–8.3 and MySQL 5.4–8.x as stated by the project); careful attention to PHP extensions and version compatibility is required for installations. (github.com)
• UI and theming are functional but can appear dated compared with modern SaaS booking platforms; advanced UX customization may require frontend asset tooling (repository includes JS/package artifacts).
• No hosted SaaS tier is bundled with the open-source distribution; commercial hosting/managed options are offered separately by the vendor.

GRR is a focused, mature open-source solution for organisations that need capable, self-hosted resource reservation with administrative delegation and integration options. It is best suited to environments that can meet the PHP/MySQL requirements and are willing to host and maintain the application.