What this does
Rewrites YAML in flow style on as few lines as possible: name: app and a list of ports becomes {name: app, ports: [80, 443]}. Comments are dropped. Anchors and aliases are kept, so the data is identical to the input.
When it is useful
Passing a small config through an environment variable or a command-line argument, embedding YAML in a one-line field, or comparing two files without whitespace noise.
Notes
YAML cannot drop the space after a comma or colon, so the saving is mostly indentation and line breaks. For very large data, JSON is usually the more compact choice; the YAML to JSON converter does that.
Multi-document input produces one flow-style line per document, separated by ---.
Privacy
Everything runs in your browser. Your input is never uploaded, stored, or put in the URL.