Paste your YAML below to check the syntax instantly. Catch indentation and formatting errors, and convert valid YAML to JSON. Works with Kubernetes, Docker Compose, and GitHub Actions files.
YAML stands for YAML Ain't Markup Language. It is a human-readable data serialisation format used mainly for configuration files. Docker Compose files, Kubernetes manifests, GitHub Actions workflows, Ansible playbooks, and countless other tools use YAML for their configuration. YAML uses indentation to represent structure which makes it clean to read but also easy to break with a single wrong space.
This tool validates your YAML syntax in real time as you type. When the YAML is valid it also converts it to JSON so you can see the parsed structure and confirm it matches what you expect. When the YAML is invalid it shows you the exact error message and location so you can fix it fast.
The most common YAML error is using tabs instead of spaces for indentation. YAML does not allow tab characters for indentation at all. You must use spaces. Configure your editor to insert spaces when you press Tab and this whole class of errors disappears.
The second most common error is inconsistent indentation. Every level of nesting must use the same number of spaces throughout the file. Mixing two spaces in one place and four in another breaks the structure. Pick a consistent indent, usually two spaces, and keep it the same everywhere.
Other frequent errors include a missing colon after a key, a missing space after the colon (YAML needs the space, so it is key: value not key:value), incorrect string quoting when a value contains special characters like colons or the at sign, and using the wrong list syntax. This validator points to the exact line so you do not have to hunt for these by eye.
Kubernetes manifests are one of the biggest sources of YAML frustration because a small indentation mistake can make an entire deployment fail with a confusing error. This tool checks the raw YAML syntax which catches the structural problems before you ever apply the file to a cluster. Paste your deployment, service, or configmap YAML here to confirm the syntax is valid, then convert it to JSON to double check the structure matches the Kubernetes schema you expect.
Docker Compose files and GitHub Actions workflow files are both YAML and both very sensitive to indentation. A misaligned service definition in a compose file or a wrongly nested step in a workflow will fail silently or with an unhelpful message. Validate the file here first to rule out YAML syntax problems, so that when something does not work you know the issue is in the configuration values and not the YAML structure itself.
Every valid YAML document can be converted to JSON because YAML is a superset of JSON. When your YAML passes validation this tool automatically shows the JSON equivalent on the right. This is useful when you need to feed configuration into a system that expects JSON, when you want to inspect the exact parsed structure, or when you are debugging why a value is being read differently than you intended.
YAML is a superset of JSON, which means all valid JSON is also valid YAML. YAML is friendlier to write by hand because it does not require quotes around most strings, curly braces around objects, or commas between items. It also supports comments, which JSON does not. JSON is better for machine generation and API responses where the extra strictness and lack of ambiguity is an advantage. Many teams write configuration in YAML for readability and let their tools convert it to JSON internally.
No. YAML does not allow tab characters for indentation. You must use spaces. This is the single most common cause of YAML errors. Most editors can be set to insert spaces when you press the Tab key, which prevents the problem entirely.
Two spaces per level is the most common convention and is used by most Kubernetes and Docker examples. The exact number does not matter as long as it is consistent throughout the entire file. Never mix different indent sizes in the same document.
Yes. When your YAML is valid the tool automatically shows the JSON equivalent on the right side. You can copy the JSON with the Copy JSON button. This works for any valid YAML including Kubernetes manifests and Docker Compose files.
The most likely causes are a tab character somewhere in the file, inconsistent indentation between sections, or a missing space after a colon. This validator shows the exact line and error message so you can find and fix the problem. Note that this checks YAML syntax, not whether the fields match the Kubernetes schema.
Yes. Everything runs entirely in your browser using a JavaScript YAML parser. Your YAML is never sent to any server and is not stored anywhere.