What does the YAML Formatter, Validator, and Tree Viewer do?
Use this tool when you need a browser utility that parses YAML into a normalized document, JSON, or an expandable value tree. It accepts one YAML document and returns formatted YAML, two-space JSON, or a structured tree. Results are deterministic for the same input except where cryptographic randomness, current time, or a live provider response is part of the task.
Choose the view that matches the review task
Use formatted YAML for configuration editing, JSON for systems that require strict JSON, and Tree view to inspect deep values without scanning indentation.
How do you use it?
- Paste one YAML document or load the included example.
- Choose formatted YAML, JSON, or Tree view.
- Run the parser and inspect, copy, or download the normalized result.
Worked example
Normalize a short YAML mapping
Input
project: KitLumi
tools:
- json
- yamlOutput
project: KitLumi
tools:
- json
- yamlThe YAML is parsed as data before it is emitted or displayed as a tree.
Common errors and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| A bad indentation error appears. | Nested YAML levels are not aligned consistently. | Use spaces, align siblings, and avoid tab indentation. |
| Comments disappear after formatting. | The formatter normalizes parsed data rather than editing the original concrete syntax tree. | Keep a source-controlled original when comments and anchor style must be preserved. |
Important behavior of YAML Formatter
Formatting through a data model does not preserve comments, anchors, aliases, or the exact original scalar style.
Standards and implementation references
- YAML 1.2.2 specification (opens in a new tab)Defines YAML syntax and representation models.
- js-yaml documentation (opens in a new tab)Documents the local parser and dumper used by the tool.
Frequently asked questions about YAML Formatter
Does the YAML Formatter upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the YAML Formatter accept?
It accepts one YAML document. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the YAML Formatter produce?
It produces formatted YAML, two-space JSON, or a structured tree. Copy and download controls appear when the output format supports them.
What limitation should I know?
Formatting through a data model does not preserve comments, anchors, aliases, or the exact original scalar style.
What changed?
Added YAML validation, YAML formatting, YAML to JSON, Expandable tree view, responsive controls, explicit runtime disclosure, and task-specific examples and limitations.