Data & JSON
YAML Validator & Formatter
Validate and format YAML/YML locally, locate syntax errors and convert YAML to JSON. Choose indentation, copy and download. Supports one YAML 1.2 Core document with no uploads.
About this tool
Edit YAML or YML, check indentation, duplicate keys and syntax, then format or convert to JSON. Choose 2/4-space indentation, locate errors, copy and download. All processing stays in your browser.
Best use cases
- Find YAML syntax issues in Docker Compose, Kubernetes and CI configuration files.
- Tidy configuration snippets or convert YAML data to JSON for API debugging.
How to use it
- Paste one YAML 1.2 Core document or load the example. Each run supports 200,000 characters.
- Choose indentation, then validate, format or convert to JSON. Correct issues using reported line and column positions.
- Copy or download .yaml/.json output. Input changes clear old results, and processing can be cancelled.
FAQ
Does valid syntax mean the configuration can be deployed?
No. This checks YAML syntax and the supported feature set, without validating Kubernetes resource fields, Docker Compose versions, CI platform rules or deployments.
What cannot be converted to JSON?
Cycles, non-string mapping keys, unsafe integers, NaN, Infinity and negative zero report errors. Quote identifiers that must remain text. Alias expansion, nesting depth and output size are limited.
Are multiple documents, custom tags and dates supported?
This release supports one YAML 1.2 Core document, without custom tags or extended types. Plain date text remains a string; formatting retains comments and anchor meaning.