• React Native Testing Library (Library) - A library to create maintainable tests and test public APIs with React Native apps.
  • React Testing Library (Library) - A library that builds on top of DOM Testing Library by adding APIs for working with React components.
  • ReactiveX (Library) - A software library that allows imperative programming languages to operate on sequences of data regardless of whether the data is synchronous or asynchronous.
  • Reason Testing Library (Library) - Refers to bindings for the Reason programming language to use the Testing Library framework.
  • ReasonReact (Library) - A collection of zero-runtime type definitions and lightweight utilities for React.
  • Rebol (Language) - A cross-platform[6] data exchange language and a multi-paradigm dynamic programming language designed by Carl Sassenrath for network communications and distributed computing.
  • Red (Language) - A programming language designed to overcome the limitations of the programming language Rebol.
  • Redis (Database) - An in-memory key–value database, used as a distributed cache and message broker, with optional durability.
  • Redshift (Database) - A data warehouse product which forms part of the larger cloud-computing platform Amazon Web Services.
  • Redux (Library) - An open-source JavaScript library for managing and centralizing application state.
  • Remix (Framework) - A full stack web framework that lets you focus on the user interface and work back through web standards to deliver a fast, slick, and resilient user experience.
  • repository (Category) - A centralized digital storage location for software projects, holding source code, libraries, dependencies, configurations, and other digital assets, acting as a version-controlled hub for developers to collaborate, manage changes, and distribute software.
  • Rexx (Language) - A high-level programming language developed at IBM with both proprietary and open source Rexx interpreters for a wide range of computing platforms, and compilers for IBM mainframe computers.
  • RHEL (Operating system) - A commercial Linux distribution developed by Red Hat.
  • Roxen (Server) - A free software web server produced by Roxen Internet Software, a company based in Linköping, Sweden.
  • Rspec (Language) - A computer domain-specific language (DSL) (particular application domain) testing tool written in the programming language Ruby to test Ruby code.
  • Ruby (Language) - A general-purpose programming language designed with an emphasis on programming productivity and simplicity.
  • Ruby on Rails (Stack) - A server-side web application framework written in Ruby under the MIT License.
  • Rust (Language) - A general-purpose programming language. It is noted for its emphasis on performance, type safety, concurrency, and memory safety.
  • RxJava (Library) - A library for composing asynchronous and event-based programs using observable sequences for the Java VM.