Convert a YAML 1.2 document to JSON privately. Support mappings, sequences and core scalar types, preserve exact integers and review errors in a cancellable local worker.
Your YAML stays on your device. The open-source yaml parser is self-hosted, and conversion runs locally without accounts, uploads or saved input history. A disposable worker supports cancellation and a time limit. JSON is generated from the parsed syntax tree without executing values or loading external resources.
One YAML 1.2 document using the core schema: string-keyed mappings, sequences, strings, booleans, null, integers and supported finite decimal numbers. Block and folded strings and flow collections are supported. Anchors without references may appear, but alias references and the reserved mapping key << are rejected. Empty or comment-only input is rejected; explicit null is supported. YAML 1.1 directives and multiple documents are not supported.
Duplicate mapping keys, non-string or complex keys, aliases, merge keys, unsupported/custom tags and non-finite numbers are rejected. Standard core tags are accepted. Timestamp and binary tags are not resolved. Quote scalar keys that need to be strings. Resolve aliases and merged mappings into explicit values before conversion.
Integer values use BigInt while parsing and are emitted as exact JSON decimal numbers. YAML hexadecimal and octal integers normalize to decimal notation. Supported finite decimal numbers retain their source digits while plus signs, leading zeros and omitted digits around a decimal point are adapted to JSON syntax. Non-finite results, including overflowing decimal exponents, are rejected. Consumers of the output may still round large numbers. Quote values that must remain strings, especially leading-zero IDs.
YAML 1.2 core interpretation is used: plain yes/no and ordinary date-looking text remain strings; true/false and numeric forms are typed values. Comments, anchors, scalar quoting styles and other YAML presentation details are not represented in JSON. This is data conversion, not a YAML round-trip editor or application-schema validator.
Input accepts 100,000 UTF-16 units. Traversal is limited to 20,000 nodes including mapping keys, 100 nested containers and 1,000,000 JSON output units. A five-second deadline includes module-worker startup and parsing. Cancel, field edits and page exit terminate pending work and ignore late results. Failed or timed-out runs expose no partial output. Use a current browser with module-worker support.
The self-hosted yaml 2.9.1 parser by Eemeli Aro is used under the ISC license. Its npm tarball integrity was verified, and its browser modules are copied unmodified with the license retained. No external requests, input storage, models or servers process your YAML. Copy and JSON downloads contain only the converted output. Clear keeps indentation; Example restores two spaces.
