md2json

A Unix-filter CLI that parses a single Markdown document (CommonMark + GFM, optional YAML frontmatter) and writes a JSON envelope to stdout:

{ "frontmatter": { ... }, "ast": { "type": "root", "children": [ ... ] } }

The ast is an mdast-compatible subset. Parsing is delegated to goldmark with its official GFM, frontmatter, and footnote extensions.

Errors go to stderr with a single canonical regex ^md2json: <path>:<line>:<col>: <msg>$ and a non-zero exit code; nothing is written to stdout on failure.

Install

Homebrew (macOS / Linux)

brew install sunfmin/tap/md2json

(Or brew tap sunfmin/tap && brew install md2json.)

The tap lives at sunfmin/homebrew-tap and installs prebuilt binaries from this repo's GitHub Releases.

go install

go install github.com/sunfmin/md2json@latest

Prebuilt binaries

Each tagged release publishes static binaries for darwin/{amd64,arm64}, linux/{amd64,arm64}, and windows/amd64, plus a SHA256SUMS manifest. See the latest release.

Usage

md2json post.md          # parse a file
md2json < post.md        # parse stdin
md2json -                # explicit stdin sentinel
md2json --no-position    # strip mdast `position` fields
md2json --frontmatter-only post.md   # emit only the YAML frontmatter
md2json -V               # version
md2json -h               # full flag/usage help

Exit codes

Code	Meaning
0	success — JSON envelope on stdout
1	input error (invalid UTF-8, malformed frontmatter, parse failure)
2	usage error (unknown flag, bad argv)

License

No license yet — treat as "all rights reserved" until one is added.