Aiven has made its developer documentation an open source project, allowing external contributions to improve the content. The company uses a "docs-as-code" approach, which involves using issue trackers, version control, plain text markup, code reviews, and automated tests for documentation. Aiven's chosen technologies include Sphinx, Vale, MermaidJS, GitHub, and Creative Commons licensing. Contributors can use various tools such as Visual Studio Code, GitHub Desktop, or GitHub Codespaces to make changes and submit pull requests. The company encourages feedback and suggestions for improvement through its documentation project.