YAML vs JSON, Quick Facts
- •YAML is a superset-like alternative to JSON: every valid JSON document is (almost) valid YAML, but YAML adds comments, multi-line strings, and a less punctuation-heavy syntax.
- •YAML uses indentation to show structure, like Python, so mixing tabs and spaces is a common source of parse errors.
- •Docker Compose, Kubernetes manifests, GitHub Actions, and Ansible all use YAML as their primary configuration format.
- •Unlike JSON, YAML supports comments starting with
#, which is why config files are often written in YAML and generated as JSON for machines to consume.
The Real Problem This Solves
Config files are written in YAML for humans (comments, less punctuation) but APIs and many programming languages expect JSON. Converting by hand means carefully re-adding every brace, bracket, and quote, or removing them, without breaking the structure.
This tool converts instantly in both directions and points out exactly what's wrong when the input isn't valid.
How the Conversion Works
Both formats describe the same underlying data structures, objects (maps), arrays (lists), strings, numbers, and booleans. Converting means fully parsing one format into that structure in memory, then serialising it back out using the other format's syntax rules.
Example: the YAML tools: and the JSON
- JSON Formatter
- Regex Tester{"tools": ["JSON Formatter", "Regex Tester"]} represent identical data, an object with one key holding a list of two strings, just written with different punctuation conventions.
Frequently Asked Questions
Why is my YAML failing to parse?
The most common cause is inconsistent indentation. YAML requires spaces (not tabs) and is strict about how many spaces mark each nesting level. Mixing tab and space indentation, or misaligning list items, is the single most common YAML error.
Does converting JSON to YAML preserve comments?
No. JSON has no comment syntax, so if you start from JSON there are no comments to preserve. Converting YAML with comments to JSON will also drop those comments, since JSON cannot represent them either.
Can YAML represent everything JSON can?
Yes, and more. Every JSON document can be losslessly represented in YAML. The reverse isn't always true, YAML features like comments, anchors and aliases (reusable blocks), and multi-line strings have no JSON equivalent.
Is my data uploaded anywhere?
No. Conversion happens entirely in your browser using a JavaScript YAML parser; nothing is sent to a server.
What YAML version does this support?
This tool follows the YAML 1.2 specification, the version used by virtually all modern tools including Kubernetes, Docker Compose, and GitHub Actions.
Comparing two versions of this config?
Spot exactly what changed between two YAML or JSON files with our Diff Checker, line by line.
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