R3: The Ideal Free Choice for Building Internal Tools

R3: The Ideal Free Choice for Building Internal Tools

R3 is an open-source free software development kit (SDK) that offers a comprehensive range of tools and libraries for effortlessly constructing internal tools.

Why R3?

Here's why R3 stands out as the ultimate option:

  1. Simplicity: R3 employs a straightforward and user-friendly syntax, facilitating a swift learning process. This simplicity empowers developers to swiftly prototype and construct internal tools without encountering any steep learning curves.
  2. Flexibility: R3 supports various programming languages, including JavaScript, Python, and Ruby, granting developers the freedom to choose the language they feel most proficient in. This flexibility empowers teams to utilize their existing skill sets and work more efficiently.
  3. Modularity: R3 has been meticulously designed with a modular approach, enabling developers to effortlessly incorporate or eliminate features as required. This modular framework empowers teams to fashion custom internal tools tailored to their specific needs, bolstering productivity and efficiency.
  4. Seamless Integration: R3 seamlessly integrates with existing tools, systems, databases, APIs, and third-party services. This integration capability allows teams to leverage their current infrastructure and data sources, simplifying the process of constructing powerful and interconnected internal tools.
  5. Thriving Community: R3 has a vibrant and supportive community of developers who actively contribute to its advancement and provide valuable assistance to one another. This thriving community ensures that R3 is consistently updated, maintained, and enhanced, guaranteeing a reliable and sustainable solution for constructing internal tools.


  • Fast results: Quickly replace grown, spreadsheet based 'solutions' with proper multi-user applications.
  • It can count: Summarize records, do date calculations, apply business rules and much more.
  • Make things visible: Show tasks on Gantt charts, generate diagrams or display information-dense lists.
  • Workflows included: Adjust forms based on the current state of a record, export to PDF or send notifications.
  • Compliance tools: With roles and access policies, REI3 can give and restrict access even on a per-record basis.
  • End-to-end encryption: Built-in support for E2EE - easy to use with integrated key management features.
  • Integration options: REI3 can serve as and connect to REST endpoints, create or import CSV files and also includes ICS access for regularly updating calendars on devices.
  • Ready for mobile: Works well on all devices, with specific mobile settings and PWA features for great-feeling apps.
  • Fulltext search: Users can quickly find desired content by using search phrases and language specific lookups.
  • Blazingly fast: REI3 is built to take advantage of multi-core processors and communicates with clients over bi-directional data channels.
  • Security features: Apply password policies, block brute-force attempts and enable MFA for your users.
  • Fully transparent: Directly read and even change data in the REI3 database - everything is human-readable.
  • Selfhosted: Run REI3 as you wish, locally or in the cloud - with full control on where your data is located.
  • Enterprise-ready: Adjust REI3 to your corporate identity, manage users & access via LDAP and grow with your organization by extending applications and clustering REI3.


  • MIT License

Resources & Download

REI3 - Business Software for Everyone
Open and powerful low-code development with REI3. Free to use and easy to install on your own systems - anyone can meet their business software needs with REI3.
GitHub - r3-team/r3: REI3 - Free and open low code
REI3 - Free and open low code. Contribute to r3-team/r3 development by creating an account on GitHub.

Open-source Apps


Medical Apps




Dev. Resources