5 min read
YAML Validator
Check YAML syntax and inspect parsing errors instantly.
How to use this YAML validator
Paste your YAML configuration into the editor, or open a local .yaml or .yml file. Select Validate YAML to check whether the document can be parsed. If the syntax is valid, the tool shows a JSON preview of the parsed data. If the YAML is invalid, review the parser message and its line and column details, then correct the input and validate it again.
Paste a snippet or open a local file. Use an example if you want to test the validator first.
See whether the document parses. Errors include the location reported by the parser when available.
For valid YAML, copy the JSON preview or download it for use in your workflow.
What does YAML validation check?
YAML is a human-readable data format used for application settings, Docker Compose files, Kubernetes manifests, CI workflows and automation. Unlike JSON, YAML uses indentation and whitespace to express structure, so small syntax mistakes can change how a file is interpreted or prevent it from being read.
This validator parses your input using the open-source YAML JavaScript parser in your browser. It can identify syntax problems such as inconsistent indentation, missing separators, malformed quotes, invalid collection structure and duplicate mapping keys. The exact diagnostic depends on the parser and the input. For the format definition, see the YAML 1.2.2 specification.
Common YAML errors and how to fix them
Incorrect indentation
YAML uses indentation to represent nesting. Use spaces consistently and align keys at the same level.
server: host: localhost port: 8080
Missing space after a colon
In a standard block mapping, include a space between a key’s colon and its value.
# Correct mode: production # Usually incorrect as a block mapping mode:production
Unquoted special characters
Some characters have a special meaning in YAML. If a value contains syntax-sensitive characters, quote it where appropriate.
message: "Build completed: review the logs"
Duplicate mapping keys
Repeating a key can cause different tools to handle the value inconsistently. Keep mapping keys unique and check the reported error before using the configuration.
Frequently asked questions
Is this YAML validator free?
Yes. You can validate YAML and inspect the JSON preview without creating an account.
Is my YAML uploaded to a server?
The validator parses your input in your browser. The YAML text is not sent to Ccodelearner’s server by the validation code. If you load a file, it is read locally in your browser.
Does it validate Kubernetes or Docker Compose schemas?
No. It checks YAML syntax and parses the document. Platform-specific schema validation is a separate step.
Can I validate multiple YAML documents?
The validator supports YAML streams containing documents separated by the standard document marker. The JSON preview represents the parsed documents as a list.
What happens if the YAML is invalid?
The tool displays the parser’s error message and line or column information when available. Correct the reported area and validate again.
Can I convert YAML to JSON?
Yes. When the YAML is valid, copy the JSON preview or use the Ccodelearner tools directory to find related developer utilities.
More developer tools
Continue working with related utilities from Ccodelearner.
For safety, do not paste production secrets into third-party websites. This tool runs locally, but browser extensions and other software on your device may still have access to page content.
Validate YAML syntax online
Use this free YAML validator to check YAML syntax online before using a configuration file in a development or deployment workflow. It is designed for common developer tasks, including checking application settings, CI pipeline snippets, and YAML files used with containers or infrastructure tools.
The validator reports parser errors when available and creates a JSON preview for valid input. It does not upload the YAML text for validation, and it does not replace platform-specific schema checks. Always review the result before using a configuration in production.
YAML syntax validation versus schema validation
Syntax validation checks whether a YAML parser can read the document. Schema validation checks whether the parsed data follows the requirements of a specific application or platform. A document can pass YAML syntax validation and still contain an unsupported field, invalid resource definition, or incorrect application setting. Use the validation tool appropriate to your target platform for that second step.
Related tools
Explore the Ccodelearner tools directory or use the JSON Formatter and Validator for JSON-specific syntax checks.
