What is json-schema-dev?

jsonschema.dev is a free online tool that lets you write and test JSON Schema documents directly in your browser. Think of it as a playground or scratchpad: you type out a schema on one side, some sample data on the other, and immediately see whether the data passes or fails validation. The closest analogy is something like JSFiddle, but specifically built for the JSON Schema community. JSON Schema is a way to describe what a valid JSON document should look like, which fields are required, what types they should be, what format a date or email should follow, and so on. It's widely used in the real world. VS Code uses it under the hood to provide autocomplete and validation for configuration files. OpenAPI (formerly Swagger) relies on a subset of it to define API request and response shapes. Tools like Webpack and ESLint also depend on it. The tool exists because the JSON Schema community needed an easy way to share and debug schemas collaboratively. If someone runs into a confusing validation error, they can paste their schema and data into the site and share a link rather than trying to explain the problem in text. Unlike some other online validators that send your data to a server for processing, this one runs entirely in your browser using a validation library called AJV. That means no round-trips to a server and your data never leaves your machine. The project is built with Vue.js and deployed automatically through Netlify, which also generates preview links for pull requests so contributors can review changes before they go live. Contributions are welcome but should be directed at the develop branch, not master. If you work with APIs, configuration files, or any system that involves structured JSON data, this is a handy tool to have bookmarked for quick testing and troubleshooting.