YAML validator, JSON converter
YAML validation with the error's place and cause, and a YAML ⇄ JSON converter.
Result
Calculated in your browser — nothing is sent to the server
Practice on a machine
Lab “Repair a persistent address”
In a Linux terminal
yamllint docker-compose.yml
# indentation, tabs, duplicate keys
docker compose config
# check a compose file
sudo netplan try
# apply netplan, roll back after 120 s
cloud-init schema --config-file user-data
# check a cloud-config
yq -o=json '.' config.yaml
# YAML to JSON (Mike Farah's yq)
Keep in mindYAML indents with spaces only: a tab is an error, and one space off moves a key to another level.
FAQ
Why does netplan say “Invalid YAML” when everything looks aligned?
Most often it is a tab in the indentation or keys of one level indented differently: paste the
file here and the line lights up. Then run sudo netplan generate.
What is the difference between YAML 1.1 and 1.2?
In 1.1 (PyYAML, Ansible, netplan), yes, no, on, off are booleans and 0755 is octal; in
1.2 they are strings and a decimal number. Quote such values.
How do I convert YAML to JSON?
Paste the YAML and the JSON appears on the right. Comments are dropped, and anchors & and aliases
* expand into full values.