About JSON Hearth
Developer tools that keep your data with you.
JSON Hearth is a collection of focused tools for viewing, validating, comparing and transforming JSON, JSONL and adjacent data formats.
Why it exists
Everyday data work should not require creating an account or uploading an API response, log file or configuration document to an unknown server. The tools here are designed to run in your browser so the data you paste or open stays on your device.
What you can do
Open JSON and JSONL, format or repair documents, compare payloads, test JSONPath expressions, validate schemas, convert CSV and YAML, and generate useful TypeScript, Go and Java types.
Browse all tools →What “local” means
Tool input is processed by code running in the browser tab. It is not sent to an application server, saved to an account or used for model training. The site itself may later use privacy-conscious analytics and advertising; those services never receive the JSON content entered into a tool.