YAML to JSON Converter
Parse YAML config files into clean JSON, with full support for anchors, block scalars and flow style.
YAML is the lingua franca of modern config - docker-compose, Kubernetes, GitHub Actions, Ansible - but it is also the easiest format to get wrong by hand, because indentation errors fail silently at the worst moments. Converting a YAML file to JSON gives you an unambiguous reading of exactly what the parser sees, which is invaluable for debugging and for feeding config into tools that only accept JSON.
Paste your YAML and press Convert. The parser handles the full practical grammar: nested mappings and sequences, quoted strings, comments, multi-line strings with block scalars, and flow-style collections. Anchors and aliases are resolved, so a config that reuses a block through &defaults and *defaults produces the complete expanded JSON.
The conversion runs in your browser using the standard YAML library, so the result matches what your actual tools parse. Configs often contain secrets, so nothing is uploaded - the file is read and converted entirely on your machine.
Features
- Full YAML parsing: block and flow style, quoted strings, comments and multi-line scalars.
- Anchors (&name) and aliases (*name) resolved into their fully expanded values.
- Multi-document streams handled cleanly with the first document converted.
- Numbers, booleans, null and timestamps mapped to their native JSON types.
- Pretty-printed JSON output with two-space indentation.
- Clear error message when the YAML is malformed, with the cause identified.
- Fully offline - the YAML never leaves your browser.
How to Use
- 1
Paste YAML
Enter any YAML document - from a compose file, a workflow, or a hand-written config. Anchors and flow style are supported.
- 2
Convert
Press Convert to JSON. The parser resolves the structure and emits pretty-printed JSON.
- 3
Review types
Check that numbers, booleans and null came through with the right types, which the parser handles automatically.
- 4
Copy or download
Copy the JSON for your code or API, or download it as a .json file.
Example
Compose-style YAML to JSON
version: "3.8"
services:
web:
image: nginx
ports:
- "80:80"↓
{
"version": "3.8",
"services": {
"web": {
"image": "nginx",
"ports": ["80:80"]
}
}
}Anchors resolved
defaults: &d
retries: 3
task:
<<: *d
name: build↓
{
"defaults": { "retries": 3 },
"task": { "retries": 3, "name": "build" }
}Common Problems
Inconsistent indentation
YAML derives structure from indentation, so a stray space changes the shape. The parser reports a clear error with the location when indentation is ambiguous, instead of silently producing the wrong tree.
Values that look like the wrong type
An unquoted value like yes, no, on or null has special YAML meaning and converts accordingly. If a config field must stay a string, quote it in the YAML - the parser respects quotes.
Missing quotes around ports and versions
In compose files, "80:80" is a string that needs quotes; without them some parsers treat it as invalid. The converter reports the parse problem so you can fix the source rather than trusting a silent wrong value.
Tab characters in indentation
YAML forbids tabs for indentation. The parser flags them rather than guessing, which catches a whole class of copy-paste config bugs instantly.
Expecting comments to survive
Comments are not data and do not appear in JSON. If you need to preserve annotations, keep the YAML as the source of truth and treat the JSON as its machine-readable form.
Secrets in committed configs
Converting to JSON does not make secrets safer - both formats are plaintext. Use a secrets manager for real credentials regardless of which format they live in.
A document marker splitting your file
A leading --- or a second --- mid-file separates documents. The converter reads the first document, which covers the vast majority of config files; multi-document streams should be split before converting.
Technical Details
The parser is the standard YAML library, so it implements the full YAML 1.2 grammar: block mappings and sequences, flow collections, quoted scalars with escapes, block scalars (| and >), comments and document markers.
Anchors and aliases are resolved during parsing, and merge keys (<<) are applied, so the JSON is the fully expanded view of the config - what a tool would actually read.
YAML's type system maps onto JSON: integers and floats become numbers, true/false become booleans, null and ~ become null, and quoted or ambiguous values become strings.
Output is formatted with JSON.stringify(value, null, 2), producing stable, diff-friendly JSON.
Processing is local and synchronous. The YAML is parsed in your browser and never transmitted.
Because the parser is the same engine behind popular config tooling, converting a compose or workflow file here produces the same result that the tool itself would read - which is exactly the debugging check you want before a deploy.
Timestamps and other YAML-typed scalars are converted to their JSON representation; anything that does not map cleanly falls back to a string, so no data is lost in the translation.
Frequently Asked Questions
Why does yes convert to a string in my output?
With the YAML 1.2 core schema that modern tools use, yes and no are plain strings - only true and false are booleans. That matches what docker-compose and Kubernetes actually parse.
Are anchors and aliases expanded?
Yes. A config that reuses a block via &defaults and *defaults converts to the fully expanded JSON, with every reference copied into place - which is exactly what the consuming tool sees.
What about multi-line strings?
Block scalars using | or > are parsed into their complete string value, folding and preserving newlines per the YAML rules, and appear as a normal JSON string.
Will my comments be preserved?
No. Comments are stripped, because JSON has no comment syntax. They remain in the source YAML, which should stay your editable copy.
Is my config uploaded anywhere?
No. Parsing happens entirely in your browser. The YAML is processed in memory and never transmitted, stored or logged.
Can I convert back to YAML?
Yes - use the JSON to YAML converter. The two tools round-trip a document, though comments and key order are the natural losses of going through JSON.
Why did my parse fail on a port like "80:80"?
In YAML, an unquoted "80:80" can be read as a mapping or a sexagesimal value depending on the schema. Compose files quote such values for that reason. The parser reports the ambiguity so you can quote the value in the source.
Data & Privacy
Your data stays in your browser. Nothing is uploaded.
- Processing
- Local
- Upload
- None
- Server Storage
- None
- Account
- Not required
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