Free JSON Tools — Format, Validate, Convert

JSON is the format most APIs, configuration files and log lines are written in, which makes a good set of JSON tools one of the most used things in a developer's day. This page collects the DevStackKit tools for working with JSON: parse a payload and see exactly where it breaks, beautify or minify it, compare two responses line by line, check a document against a schema, and query nested data with a path expression.

The converters on this page move data between JSON, YAML and TOML, which is what you need when a deployment file, a build setting and an API all want the same data in different clothes. Every tool runs inside your browser, so API responses, tokens and customer records you paste are never sent to a server, and the tools keep working offline once they have been opened.

Start with the JSON Parser if you only need to know whether a document is valid. Choose the Beautifier when you want readable indentation, Compare when two payloads should match, and the Schema Validator when a contract has to be enforced. The same group also holds the XML, SQL and GraphQL formatters and the URL, query string and diff tools. Each tool shows clear error messages with a line and column, keeps your input when something goes wrong, and gives you a one-click copy of the result.