# YAML to JSON Converter | Expose Hidden Data Changes

Convert YAML to JSON locally as you type. Expose duplicate keys, unsafe integers, alias cycles and presentation loss before fixtures reach a test run.

Canonical: https://tamperbox.dev/yaml-to-json

Docs: https://docs.tamperbox.dev/tools/yaml-to-json.md

Updated: 2026-10-26

Reviewed: 2026-10-24

## How it works

The page parses YAML with the JSON-compatible schema in a browser worker and rewrites JSON after each valid edit. It rejects duplicate keys, unsafe integers, cyclic aliases, unsupported tags and excessive complexity; the full method, every rule and worked examples are on [docs.tamperbox.dev](https://docs.tamperbox.dev/tools/yaml-to-json/).

## Limits and interpretation

A pass means the resolved YAML value fits the JSON data model and can be emitted as JSON. Comments, anchor names, aliases, scalar spelling and formatting are presentation rather than JSON values and are not preserved. Input stays in the browser and is limited to 1,000,000 characters, 80 levels, 100 aliases and 100,000 values.

## Frequently asked questions

### Does the converter execute YAML tags or embedded text?

No. It accepts the JSON-compatible schema and refuses unsupported tags; strings are never treated as commands, templates or addresses to fetch.

### Why are aliases flattened in the JSON output?

JSON has no anchor or alias syntax. Acyclic aliases resolve to their values, while cycles are rejected because JSON cannot represent them.

### How do I prove the conversion kept my test data?

Convert the JSON output back to YAML, parse both ends under the same data model and deep-compare the values. Validate the JSON against the application's schema separately.

## References

[YAML 1.2.2, representation graph](https://yaml.org/spec/1.2.2/#chapter-3-processes-and-models) and [RFC 8259, JSON values](https://www.rfc-editor.org/rfc/rfc8259#section-3) define the boundary used here.