OnePreview

Open Markdown and developer files in OnePreview on iPhone and iPad. OnePreview renders GitHub-style Markdown, MDX, TextBundle and TextPack packages, JSON, JSONL, YAML, XML, CSV, TSV, TOML, ENV, SQLite databases, source code, plain text, logs, and ZIP and TAR.GZ archives. In Files, long-press a supported document, choose Open With, then select OnePreview. A normal tap may use Apple's built-in preview for common file types. Inside OnePreview, switch between rendered Markdown and source, view Mermaid diagrams and KaTeX math with bundled assets, inspect structured data and SQLite schemas, and check archive contents before extracting. Built for developer workflows, AI-generated files, documentation review, and everyday file browsing. Processing is fast, local-first, and does not require an account.