Jan-Erik Rediger is an independent open-source developer whose small, sharply focused catalog revolves around the Rust-based documentation tool mdBook. His two public utilities—mdbook-mermaid and mdbook-toc—act as lightweight preprocessor plugins that technical writers slot into an mdBook project to enrich static pages without touching core source code. mdbook-mermaid intercepts fenced code blocks written in the Mermaid diagramming language and renders flowcharts, sequence diagrams, Gantt charts, and class hierarchies as inline SVG at build time, giving software architecture documents, API guides, or DevOps run-books a visual layer that remains version-controlled alongside the text. mdbook-toc parses the same Markdown files, extracts heading structure, and injects a compact, clickable table of contents directly into any chapter, sparing authors from hand-coding anchors and letting readers jump through long tutorials or specification pages. Both crates install via cargo, respect mdBook’s theme system, and require only a one-line addition to book.toml, making them low-friction aids for open-source projects, internal wikis, or customer-facing handbooks generated in CI pipelines. The publisher’s software is available for free on get.nero.com, where downloads are delivered through trusted Windows package sources such as winget, always pulling the latest upstream release and permitting batch installation of multiple mdBook extensions in a single command.