YAML ↔ JSON Converter
Convert between YAML and JSON with live validation — entirely in your browser. Your config never leaves the page.
- Runs in your browser
- No upload, no tracking
- Free forever
How it works
A YAML to JSON converter parses a YAML document into a data structure and re-serialises it as JSON (or the reverse), letting you move config between the two formats that tools, APIs and CI pipelines expect. It supports full YAML 1.2, validates as you type, and runs entirely in your browser so config and secrets never leave your machine. It is built by JusDB, a managed database operations team, for the config wrangling that surrounds every deployment.
- 1
Pick a direction
Use the toggle to convert YAML → JSON or JSON → YAML; the sample and labels update to match.
- 2
Paste your input
Drop YAML or JSON into the input panel — the output converts live as you type.
- 3
Catch errors instantly
Invalid input is flagged with a message describing what the parser found, so you can fix indentation or syntax fast.
- 4
Copy or download
Copy the converted output or download it as a .json or .yaml file. Nothing is ever uploaded.
Frequently asked questions
- Does it convert both directions?
- Yes. Toggle the mode to convert YAML to JSON or JSON to YAML. The output updates live as you type and reflects the current direction.
- Is my data uploaded anywhere?
- No. Conversion happens locally in your browser using js-yaml. Your config files and secrets are never sent to JusDB or any server.
- Why is my YAML invalid?
- Common causes are tabs used for indentation (YAML requires spaces), a missing space after a colon, or inconsistent indentation. The error message describes what the parser found.
- Does it preserve comments?
- No. YAML comments are stripped during conversion because JSON has no comment syntax and the parser builds a plain data structure before re-serialising.
- Which YAML version is supported?
- Full YAML 1.2 via js-yaml, including anchors, aliases, multi-line block scalars and flow collections. Anchors and aliases are resolved into concrete values when converting to JSON.
- Can I download the converted output?
- Yes. After conversion you can copy the output to your clipboard or download it as a .json or .yaml file, depending on the active direction.
YAML vs JSON: choosing a format and avoiding conversion surprises
YAML and JSON describe the same kind of data — maps, lists and scalars — but they are tuned for different audiences. YAML optimises for humans editing files by hand, while JSON optimises for unambiguous machine interchange. Converting between them is usually clean, but a handful of YAML features have no JSON equivalent, and a few YAML parsing quirks can change your data in ways that are easy to miss.
Where each format wins
YAML dominates human-authored configuration: Kubernetes manifests, GitHub Actions and other CI/CD pipelines, Docker Compose files and Ansible playbooks all favour it because comments, multi-line strings and light syntax keep large files readable. JSON wins for APIs and machine-to-machine interchange: every language parses it the same way, it streams cleanly, and there is no whitespace ambiguity to trip up a generator. A common pattern is to author in YAML and emit JSON at the boundary where a service or schema validator consumes it.
YAML pitfalls that bite
The most famous is the “Norway problem”: under YAML 1.1, unquoted no, yes, on and off parse as booleans, so a country code list containing NO silently becomes false. Quote such values to keep them strings. Indentation is significant and must use spaces — a stray tab is a hard error — and inconsistent nesting changes structure rather than failing loudly.
Anchors (&name) and aliases (*name) let one node be reused across a document; they are resolved into concrete, duplicated values when you convert to JSON. Multi-document streams separated by --- have no JSON counterpart, so only one document survives a naive conversion. Duplicate keys are rejected by strict parsers but tolerated by lenient ones, where the last value wins. Finally, YAML 1.1 and 1.2 disagree on details like the booleans above and octal number syntax, so the spec version your tool targets matters.
Lossy edge cases when converting
Some information cannot survive a round trip. Comments are dropped because JSON has no comment syntax. YAML supports non-string mapping keys and explicit tags (for example !!timestamp or custom types) that JSON cannot represent, so these are coerced or flattened. Number formatting can drift too — large integers may lose precision once they pass through a generic floating-point representation, and leading zeros or octal-looking values may be reinterpreted. When fidelity matters, validate the result against your schema rather than assuming the conversion was exact.
Privacy: everything stays in your browser
Config files routinely embed connection strings, API tokens and other secrets, so pasting them into a remote service is a real risk. This converter parses and re-serialises entirely client-side — nothing is uploaded — which makes it safe for production manifests. If you also need to pretty-print or minify the JSON side, the JSON formatter runs the same way.
Rule of thumb: keep booleans, version strings and country or currency codes quoted in YAML so the parser cannot reinterpret them, and convert to JSON at the point a machine consumes the data. JusDB's team applies these same habits when managing the config behind production databases.