A non-exhaustive list of explored as well as unexplored open-source software development tools and software applications. For an exhaustive list, take a look at Wikidata.

Application Development

Operating Systems

Platform as a Service (PaaS)

Application Packaging

Shell

Web Browser

Web development

Data Analysis

Data Visualization

Programming Languages

Markup Languages

Content Management Systems (CMS)

Computing

Container Technologies

Dictionary

Editor

Web Forum

Gaming Development

Computer Graphics

Machine Learning

Markdown Editor

Memory Mapping

Music

Natural Language Processing

Semantic Web

Web Server