YAML to JSON Converter
Transform YAML data into clean JSON format with customizable indentation.
What is YAML to JSON Conversion?
YAML to JSON conversion transforms YAML (YAML Ain’t Markup Language) data into JSON (JavaScript Object Notation) format. It is useful when you need to process configuration written in YAML with tools, languages, or APIs that expect JSON.
YAML was designed to be human-friendly. It uses indentation instead of braces, allows comments with the # character, and can express the same nested structures as JSON with far less punctuation. JSON, by contrast, is strict, machine-friendly, and universally supported by browsers, APIs, and databases.
The two formats map onto each other almost one-to-one. YAML mappings become JSON objects, YAML sequences become JSON arrays, and scalars such as strings, numbers, booleans, and nulls carry across unchanged. The converter parses the YAML into an in-memory document and then serialises that document as JSON, so the data itself is preserved.
Parsing is handled by the bundled js-yaml library, which implements YAML 1.1 support including anchors, aliases, multi-line strings, and custom tags. When something goes wrong, the error banner reports the message together with the line and column where parsing failed, which makes it easy to track down a stray indent or a missing colon.
All of this happens in your browser. The YAML you paste is never uploaded, stored, or logged, so the tool is safe for configuration files that contain internal hostnames, ports, or other sensitive settings.
Key Concepts
YAML vs JSON
YAML favours readability; JSON is stricter and more portable.
Type preservation
Strings, numbers, booleans, arrays, and nested objects survive intact.
Indentation control
Choose 2 or 4 spaces for the formatted JSON output.
Error reporting
Syntax errors include the line and column where parsing failed.
js-yaml engine
A mature parser covering YAML 1.1 features such as anchors and aliases.
Private by design
Conversion runs entirely client-side, so nothing leaves your device.
How to Use
- Paste your YAML — Copy and paste any valid YAML data into the input textarea. You can also click Load Example to load sample data.
- Choose indentation — Select 2 or 4 spaces for the output JSON formatting.
- Convert — Click Convert to JSON to generate the JSON output.
- Check for errors — If the YAML is invalid, the error banner shows the message and the line and column where parsing failed.
- Copy or download — Use the copy button on the output area or click Download .json to save the result as a file.
Conversion Reference
YAML and JSON describe the same data model. The table below maps the common YAML constructs to their JSON equivalents so you can predict exactly how a document will look after conversion.
| YAML Construct | JSON Equivalent | Example |
|---|---|---|
| Mapping | Object | { "name": "John" } |
| Sequence | Array | [ "logging", "caching" ] |
| Quoted or plain scalar | String | "api.example.com" |
| Integer or float | Number | 443 |
| true / false | Boolean | true |
| null, ~, or empty value | Null | null |
| Nested indentation | Nested object or array | { "db": { "port": 5432 } } |
| # comment | Not representable | (removed in JSON) |
Worked Examples
- Simple mapping —
name: Johnbecomes{ "name": "John" }. - Number types —
port: 443becomes{ "port": 443 }, keeping the value a number rather than a string. - Boolean —
ssl: truebecomes{ "ssl": true }. - Sequence — a dash list of logging, caching, and rate-limiting becomes a compact JSON array.
- Nested object — an indented
server:block withhostandportbecomes a nested JSON object. - Null value — a key written with no value, such as
token:, becomes{ "token": null }.
Tips and Common Mistakes
- Tabs are not allowed — YAML indentation must use spaces; a tab character is one of the most common parse errors.
- Quote ambiguous scalars — a value like
yes,on, or1.0may be reinterpreted, so quote it if you need a string. - Mind the colons — a colon followed by a space inside a plain scalar can be misread as a new key; wrap such text in quotes.
- Watch duplicate keys — later keys overwrite earlier ones, so identical names silently lose data.
- Comments disappear — JSON has no comment syntax, so any
#lines are dropped during conversion. - Read the line and column — when parsing fails, use the reported location to find the exact problem instead of scanning the whole file.
Common Use Cases
YAML appears wherever humans edit configuration, while JSON appears wherever programs consume it. Converting between them bridges those two worlds.
- Docker and Kubernetes — turn compose or manifest files into JSON for inspection by other tools.
- CI/CD pipelines — convert workflow configuration before feeding it to a JSON-based validator.
- API payloads — prepare configuration data as JSON for REST requests.
- Debugging parsing — see exactly how a parser interpreted your YAML, including inferred types.
- Language migration — port settings from a YAML config into a JavaScript or Python project that expects JSON.
- Data exchange — hand structured YAML data to a system that only reads JSON.
Frequently Asked Questions
What YAML features are supported?
This tool supports YAML 1.1 including mappings, sequences, strings, numbers, booleans, null values, multi-line strings, anchors, aliases, and custom tags.
Why convert YAML to JSON?
Many APIs and programming languages work natively with JSON. Converting YAML to JSON is common when migrating configuration files, debugging YAML parsing, or integrating with JSON-based tools and services.
Is this tool safe for sensitive data?
Yes. All processing happens entirely in your browser using JavaScript. Your YAML data is never uploaded to any server, stored in any database, or logged.
Which indentation options are available?
You can format the JSON output with either 2 spaces or 4 spaces of indentation. The choice affects readability only; the data is identical either way.
How can I download the result?
Click the Download .json button beneath the output area. The converted document is saved as converted.json on your device.
What happens if my YAML is invalid?
An error banner appears describing the problem along with the line and column where parsing failed, so you can fix the source quickly.
Are comments preserved in the JSON?
No. JSON does not support comments, so any lines beginning with # in the YAML are dropped during conversion.
Does the converter handle large files?
It runs entirely in the browser, so the practical size limit depends on your available memory. Typical configuration files convert instantly.