befold is a read-only, macOS-only viewer for Markdown, Mermaid, SVG, CSV/TSV, images, PDFs, and source code. It was built so developers can quickly review the mountains of documentation that AI coding agents like Claude Code and Codex produce. It has no editing features and focuses entirely on reading: keep a file open, and the preview refreshes within 0.2 seconds every time the file is saved. It first appeared in late May 2026 as “mmdview,” a viewer dedicated to Mermaid diagrams, and was renamed to “befold” as it expanded to cover Markdown, SVG, CSV, images, PDFs, and source code. Updates have come at a high pace ever since, and as of August 2026 the stable release has reached v1.14.2.
Key Features
- Fuzzy search via Quick Open (⌘P): Type a file name and jump straight to it. Leave the field empty and you get your recently opened files and bookmarks; relative path input like
./or../works too - Inline Git diffs: Review the changes on a branch — including what’s already committed — right inside the source view. The sidebar marks changed files with colors and badges for staged, unstaged, and untracked states, and ⌃⌘G narrows the list to changed files only
- Live reload and large-file support: When an external editor or an AI agent rewrites a file, the preview reflects it in 0.2 seconds. Markdown, CSV/TSV, and source code load incrementally, so files up to 100MB open without a wait
- CLI and Quick Look integration:
befold path/...opens several files at once from the terminal, with display options like--sidebarand--check. A bundled Quick Look extension also renders Mermaid and Markdown in Finder with a single tap of the space bar - Git-aware link resolution and tab restoration: Paths inside Markdown become links only when the target file actually exists; when it doesn’t, befold looks for the file among those tracked by git. Your previous tab layout, plus per-file zoom level and scroll position, are remembered and restored automatically on the next launch
Pros and Cons
✅ Pros
- Free, MIT-licensed open source, with the code published on GitHub
- Because it has no editing features, it can watch files safely without fighting your AI agent or editor
- Mermaid, SVG, CSV, PDF, and source code are all handled in one app — no copy-pasting into a browser or mermaid.live
- Git diffs plus change badges in the sidebar make it hard to lose track of the files an AI agent touched
- Frequent releases, with features and fixes landing continuously
⚠️ Cons
- macOS 14 (Sonoma) and later only; there are no Windows or Linux builds
- Viewing only, so fixing anything means switching to a separate editor
- A brand-new tool released only in late May 2026 — at the time of writing (August 2026) its GitHub star count is still small, and track record and community knowledge are limited
- Because it narrows its scope to reading, it isn’t suited to writing-first, WYSIWYG editing workflows the way Typora is
Comparison With Similar Tools
| Criteria | befold | Typora | VS Code | Glow |
|---|---|---|---|---|
| Form factor | Native Mac app | Native app (Mac/Win/Linux) | General-purpose code editor | CLI (terminal) |
| Editing | None (view only) | Yes (WYSIWYG) | Yes | None (view only) |
| Mermaid diagrams | Rendered out of the box | Rendered out of the box | Requires an extension | Not supported (code block only) |
| Inline Git diffs | Yes (side by side) | No | Depends on extensions | No |
| License / price | Free, MIT (OSS) | Paid (one-time) | Free, OSS | Free, OSS |
What sets befold apart from Typora for writing, VS Code as a general editor, and the text-based Glow is its deliberate stance — no editing, reading only — combined with packing Git diffs and Quick Look into a single Mac app.
Who It’s For
- Developers who want to quickly review the Markdown and Mermaid diagrams that AI coding agents like Claude Code and Codex generate
- Anyone working mainly in vim or the terminal who wants a dedicated preview pane
- Anyone who wants to read through the docs of an unfamiliar repository quickly, using Quick Open and link following
- Anyone who wants to review branch changes as a single diff, commits included
- Mac users looking for a free, open source, view-only tool that keeps things simple
Conclusion
befold occupies a clear position: a reading-only tool for humans to quickly verify the documentation AI agents mass-produce. It packs Mermaid, SVG, Git diffs, and Quick Look into one Mac app, and it’s published free and open source. The trade-offs are real — macOS only, no editing — but for developers working with AI coding agents, it’s worth trying as a preview pane parked beside the terminal.