Works with .yaml and .yml
Both extensions are the same format, so there is no separate tool for either. Add the file you have and you get a .json file named after it.
YAML to JSON Converter
Add a .yaml or .yml file and get a JSON file back. Comments are dropped and a few values change type, so read the list below before you rely on the result.
To convert yaml to json, add the .yaml or .yml file, keep JSON as the output and download the result. In our test, a 320 B YAML file with two documents became a 450 B json array of two objects in 2.8 seconds. Comments were dropped, NO became false, 01234 became 668 and .nan came out as a bare NaN, which strict JSON does not allow.
Transfers use HTTPS, and files converted on the free tier are deleted after 24 hours, so the result is not a long-term archive. Quality depends on the source file, so open the JSON file once before you share it.
FromYAMLLossless
YAML (YAML Ain't Markup Language)
A human-readable data format that uses indentation instead of braces, allows comments, and can reuse a block through anchors and aliases. It is common in configuration files for Kubernetes, Docker Compose and CI pipelines. The current spec is revision 1.2.2 from October 2021, and it is a superset of JSON. Files usually end in .yaml or .yml.
ToJSONLossless
JSON (JavaScript Object Notation)
A text format for structured data built from objects, arrays, strings, numbers, true, false and null. It has no comments and no date type, and it forbids NaN and Infinity. It must be UTF-8 when exchanged between systems, and it is the usual format for web APIs. It is defined by RFC 8259 and ECMA-404, and files end in .json.
A 320 B YAML file with two documents and a single-document 160 B file, converted on indox.org
- YAMLthe test file, 2 documents, with edge cases
- 320 B
- JSONfrom indox, array of 2 objects, 2.8 s in our test
- 450 B
- YAMLsingle clean snippet, 1 document
- 160 B
- JSONfrom indox, valid JSON, 3.2 s in our test
- 274 B
Why use indox to convert YAML to JSON?
Several documents in one file
A file split by --- lines is read as separate documents. In our test, two documents came back as one JSON array with two objects, and a single document stays a plain object.
Anchors and merge keys are resolved
Shared blocks that use &defaults and <<: *defaults are written out in full where they are used, so the JSON needs no reference support to read them.
Order and text are kept
Keys stayed in the order of the source, and non-English text is written as it is instead of as escape codes. The output uses two-space indentation, LF line endings and no byte order mark in our test.
Nothing to install
The conversion runs on indox servers, so it works in a browser on any system, without Python, yq or a code editor extension.
What happens to your YAML
Stays
- Your original YAML file, which is not touched
- The keys, values and nesting of plain mappings, lists and strings
- The order of keys, as written in the source
- Very large integers, such as 12345678901234567890, kept exact in our test
Changes
- Comments: dropped
- Anchors, aliases and merge keys: expanded into copies
- Words like NO and yes: read as false and true
- Zero-padded numbers: 01234 became 668
- Dates and timestamps: written as text
- Several documents: combined into one array
- .nan: written as NaN, which makes the JSON invalid
How do I convert YAML to JSON online?
- 1
Add your YAML file
Drop the .yaml or .yml file on the box or choose it from your device. Check first that it is plain YAML text with spaces for indentation, since the format does not allow tabs.
- 2
Keep JSON as the output and convert
Make sure JSON is the output format, then start the conversion. In our test it took 2.8 seconds from the click to Completed, with no sign-in.
- 3
Download the JSON and check the values
Open the file and look at any NO, yes, zero-padded number, date or .nan from your source. Run it through a JSON validator if another program will read it strictly.
What do I get from indox's YAML to JSON converter?
You hand over a YAML or YML file and take away JSON, for tools and code that read only JSON. The page lists what the conversion drops or changes, with values we measured, so you know before you convert whether the result fits the job.
- One JSON file from the YAML you add, in a few clicks
- Nothing installed and no account needed in our test
- Edge cases stated up front: comments, octal-looking numbers, booleans, dates and NaN
- Your original YAML file is left as it was
What are the limits for YAML to JSON?
Size
The upload box shows the live size limit before you add a file. Signing in raises it; a paid plan does not change it.
Formats
YAML in, JSON out. Pick another output on the converter if you need a different format.
Privacy
Files are encrypted in transit over HTTPS and processed on indox infrastructure.
Deletion
Free-tier files are kept for 24 hours after the job finishes, then deleted automatically.
Limits worth knowing
- Comments cannot be kept. JSON has nowhere to put them, so keep the YAML as your commented source and treat the JSON as a generated copy.
- There are no options on the converter. We saw no setting for indentation, key sorting, quoting or YAML version, so the output follows the fixed behaviour described on this page.
- indox uploads and converts the file on its servers, not in your browser. Do not upload YAML that holds passwords or keys you would not share.
- The result is not guaranteed to be strict JSON. A .nan or .inf value is written as NaN or Infinity, which RFC 8259 forbids. Replace such values in the YAML before converting.
- We tested one small file with two documents and one single-document file. We did not test custom tags such as !!binary or !!set, recursive aliases, files that are not UTF-8, very large files, or the message shown for invalid YAML.
When the result is not what you expected
| What you see | Why | What to do |
|---|---|---|
| A value turned into false or true | YAML 1.1 style reading treats NO, yes, on and off as booleans | Quote the value in the YAML, for example "NO", and convert again |
| A number changed, such as 01234 to 668 | A leading zero is read as octal | Quote the value so it stays text |
| A date is text with a space in it | JSON has no date type and the timestamp is written as a string | Parse the string in your own code or write the date as text in the YAML |
| Another program rejects the JSON | The file holds NaN, which RFC 8259 does not allow | Remove .nan and .inf from the YAML, or use null |
| I got an array and expected an object | The file had several --- documents | Split the YAML into one file per document, or read the first item of the array |
| My comments and anchor names are missing | JSON cannot store them | Keep the YAML as the source and regenerate the JSON when it changes |
| I need the file as YAML again | This tool goes one way | Use JSON to YAML, knowing comments will not return |
What do the free and paid plans add?
Free
- All converters
- Daily credit refresh
- Email support
Basic
- Access to all features
- AI Extract
- Priority conversions
- Email support
Highest priority
Premium
- Everything in Basic
- Highest priority queue
- Priority support
Pay-As-You-Go
- No subscription
- Credits never expire
- Opt-in auto-refill
- Access to all features
Which conversions are close to YAML to JSON?
YAML vs JSON: what is the difference?
| Compared on | YAML | JSON |
|---|---|---|
| Comments | Allowed with # | Not part of the format |
| Types | Reader decides: NO, yes and 01234 can become other types | Strings, numbers, true, false, null, objects, arrays |
| Reuse | Anchors, aliases and merge keys | None, a value is written out each time |
| Dates | Timestamp types in the spec | No date type, so dates are strings |
| Non-numbers | Written as .nan and .inf | NaN and Infinity are not allowed |
| Typical use | Configuration written by people | Data exchanged between programs and web APIs |
Who can use a YAML to JSON converter?
When to use it
- Turning an OpenAPI or Swagger YAML file into JSON for a tool that imports only JSON.
- Giving a JSON copy of a config file to a script, API or JavaScript app.
- Checking what a multi-document YAML file looks like as a list of JSON objects.
- Seeing how your YAML values are typed, such as whether NO or 01234 is read as text or as another type.
- Preparing data for a JSON Schema validator that expects JSON input.
Where can I read more about converting files?
Sources
- YAML Ain't Markup Language (YAML) version 1.2.2yaml.org
- RFC 9512: YAML Media TypeIETF
- RFC 8259: The JavaScript Object Notation (JSON) Data Interchange FormatIETF
- PyYAML documentationPyYAML
- JSON (JavaScript Object Notation)Library of Congress
Facts checked on November 5, 2026
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YAML to JSON FAQs
How do I convert YAML to JSON?
Add your .yaml or .yml file to the converter, keep JSON as the output and download the result. In our test a small file finished in 2.8 seconds without a login.
Are YAML comments kept in the JSON?
No. JSON has no comments, and the YAML specification says comments must not affect the data. Every # comment was gone in our test. Keep the YAML file if you need the notes.
What happens to anchors, aliases and merge keys?
They are expanded into copies. In our test a <<: *defaults merge was written out in each place that used it and the anchor name did not appear in the JSON. The key that held the defaults stayed in the output as well.
What happens to a YAML file with several documents?
A file split by --- becomes a JSON array with one object per document. In our test two documents gave an array of two objects. A file with one document gives a plain object, not an array.
Why did NO become false and 01234 become 668?
The reader follows the older YAML 1.1 rules, where NO, yes and similar words are booleans and a leading zero means octal. Put quotes around such values in the YAML, for example "NO" and "01234", and they stay text.
How are dates and timestamps converted?
They become strings, because JSON has no date type. 2024-01-15 stayed 2024-01-15 and 2024-01-15T10:30:00Z became 2024-01-15 10:30:00+00:00 in our test, with a space instead of a T. Parse them in your own code if you need a specific format.
Is the JSON always valid?
Not always. In our test .nan came out as a bare NaN, and a strict parser rejects that. A file without such values was valid JSON in our second test. Replace .nan and .inf in the YAML first.
Can I convert JSON back to YAML?
Yes, with [JSON to YAML](/convert/json-to-yaml). Comments and anchors removed on the way to JSON cannot come back, so a round trip will not match the original text.
How do I convert OpenAPI or Swagger YAML to JSON?
Add the spec file as you would any other YAML file. Check that response codes written as numbers, such as 200, are what your tool expects, because every key becomes a string in JSON.