YAML Formatter
Format multi-document YAML and validate syntax with two indent choices.
Runs in your browser. Nothing is uploaded.
Format YAML without changing its purpose
YAML Formatter makes a YAML document easier to read while keeping the operation focused on YAML. It parses the input, then writes a clean YAML representation with either two or four spaces of indentation. This page formats YAML without converting it to JSON for the user. Use the editor, paste a configuration file, or load the sample to see the result immediately.
The formatter accepts mappings, sequences, nested values, scalar strings, numbers, booleans, and null. It also understands multiple YAML documents separated by ---. Each document is formatted independently and the document separator is retained, which is useful for Kubernetes manifests and other configuration bundles.
Validate before you publish a configuration
The Validate button parses the input without replacing it with formatted output. A successful check reports that the YAML is valid. A parser failure clears the previous result and shows the message so an old successful output cannot be mistaken for the current file. Common problems include a missing colon, inconsistent indentation, an unfinished quoted string, and a sequence item at the wrong level.
Syntax validity is not the same as application validity. A document can be valid YAML and still omit a required deployment field, use the wrong environment name, or give a service a value that the receiving program does not accept. After formatting, compare the keys and types with the documentation for the application that will read the file.
Know what a format pass can lose
This tool parses YAML into JSON-compatible data before it serializes the result. Comments, anchors, aliases, custom tags, and the original scalar style are authoring details rather than ordinary values, so they may be lost. A folded block, a literal block, or a single-quoted scalar can come back in a different style. Keep the original file when those details carry meaning for reviewers or a deployment process.
Quoting still matters. Values such as yes, true, dates, and numbers may be interpreted differently by different YAML implementations. When a value is an identifier or version string, quote it in the source and review the formatted result. For a deliberate data conversion, use JSON to YAML or YAML to JSON instead.
Review private configuration in the browser
Parsing, validation, formatting, file reading, copying, and downloading happen in your browser. Nothing is uploaded, and the page does not send the YAML to an API for processing. Review secrets before you copy or download because local processing does not redact passwords, tokens, or private endpoints. If you need to inspect related structured data first, open JSON Formatter. For an XML target, compare the shape with JSON to XML.
FAQ
Does YAML Formatter upload configuration files?
The file is read, parsed, and serialized by the YAML engine in your browser. The configuration is never uploaded, and TheDevTab never receives it.
Can it format multiple YAML documents?
Yes. Format parses all documents separated by ---, serializes each one independently, and joins them with the same separator. Validate also checks all parsed documents.
Does formatting preserve YAML comments?
No. Formatting round-trips through parsed values, so comments and original scalar style are not preserved. Anchors and aliases are resolved into output values when the parser accepts them, rather than retaining their source spelling.
What indentation sizes are available?
You can choose two or four spaces for nested output. YAML is indentation-sensitive, so check the formatted result with the application that will read it.
Is valid YAML also valid application configuration?
No. Validate checks whether the input can be parsed by this YAML engine, not whether an application accepts its meaning. Required keys, allowed values, and application-specific rules need a separate check.
Why did the formatter add quotes?
The serializer quotes strings that could be read as booleans, null, numbers, dates, or YAML structure. That preserves their parsed string value when the formatted output is read again.