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Front matter parser and converter
This tool reads the front matter of Markdown files – YAML between --- lines, TOML between +++ lines or a JSON object – and turns it into JSON. You can also edit the data and write it back in YAML, TOML or JSON.
Last updated:
How it works
Add Markdown files
Paste a post or drop many .md files from a Jekyll, Hugo, Astro, Eleventy or Docusaurus site.
Extract or edit
Front matter → JSON gives one object or an array for many files. Edit & write back lets you change the data of the selected file as JSON.
Download
Save the JSON, open it in the JSON Viewer, or download the Markdown file with its new front matter.
Features
YAML, TOML and JSON
All three front matter styles are recognised automatically, including nested tables and arrays of tables in TOML.
Batch to one JSON file
Many files become an array with a "file" field, or an object keyed by file name – ready for a search index or a migration script.
Body as content
Optionally add the Markdown body as a "content" field next to the metadata.
Convert Hugo and Jekyll formats
Write the front matter back as YAML, TOML or JSON: switch a post from Hugo's +++ TOML to --- YAML without touching the body.
Clear errors
Broken YAML or TOML is reported with the file name and line number instead of silently producing empty data.
Limits & privacy
Up to 500 files, each up to 5 MB and 50 MB in total. Front matter must start on the first line of the file. Everything is parsed in your browser; files are not uploaded. See the privacy page.
FAQ
What is front matter?
A block of metadata at the very top of a Markdown file – title, date, tags – used by static site generators. YAML uses --- lines, TOML (Hugo) uses +++.
How do I convert front matter to JSON?
Paste the file or drop several, keep Front matter → JSON and copy or download the JSON. Dates stay as written, for example "2026-03-14".
Can I convert TOML front matter to YAML?
Yes. Choose Edit & write back, select the file, set Format to YAML and download it. The body of the file is kept byte for byte.
What happens to null values in TOML?
TOML has no null. Keys with null values are left out when writing TOML, and the summary tells you how many.
Is YAML with custom tags executed?
No. The parser uses the YAML core schema: unknown tags stay plain strings and aliases are limited, so a file cannot run code or blow up memory.