Top 9 Free JSON Tools Every Developer Should Know

JSON is widely used because it is easy for developers to read and for machines to parse, leading to many tools for formatting, validating, and manipulating JSON data.

JSONLint

Online validator and formatter. Users can paste JSON or provide a URL; the service checks syntax, formats output, and can compress JSON by adding the ?reformat=compress query parameter. Service URL: https://jsonlint.com/. Source code: https://github.com/circlecell/jsonlint.com.

JSONCompare

Extends JSONLint with batch validation, comparison, and merging of multiple JSON files. Offers simple, batch, and diff modes. Service URL: https://jsoncompare.com/. Source code: https://github.com/circlecell/jsoncompare.com.

jtc (JSON Test Console)

Command‑line tool for extracting, transforming, and re‑wrapping JSON elements. Allows selection of one or more elements from a source JSON and applying operations such as wrapping, filtering, or updating via a single command. Pre‑compiled binaries are available for Linux and macOS. Repository and install instructions: https://github.com/ldn-softdev/jtc.

ijson

Python library that provides an iterator‑based streaming JSON parser, enabling incremental parsing of large JSON streams into native Python objects. Supports a C‑based YAJL backend or a pure‑Python implementation. Install with pip install ijson. PyPI page: https://pypi.org/project/ijson/.

JSON Formatter & Validator

Web tool that formats and beautifies JSON for easier reading and debugging. Users can paste JSON text or supply a URL; a bookmarklet is also available for quick validation of public JSON URLs. Service URL: https://jsonformatter.curiousconcept.com/.

Altova XMLSpy JSON & XML Editor

Commercial IDE supporting both JSON and XML. Includes graphical schema designers, code generators, converters, debuggers, and processors for XSLT, XSD, XBRL, and SOAP. JSON validation is performed via the integrated RaptorXML Server. Download page: https://www.altova.com/xmlspy-xml-editor/download.

Code Beautify JSON Tools

Online suite offering a JSON viewer, editor, validator, and converters to HTML, XML, YAML, as well as an Excel‑to‑JSON converter and a minifier. Additional utilities are provided for XML, CSV, Base64, and other formats. Service URL: https://codebeautify.org/json-tools.

Visual Studio Code

Free code editor with built‑in JSON support, including IntelliSense, schema‑based validation, code folding, hover documentation, and automatic schema association. Download: https://code.visualstudio.com/Download.

Eclipse JSON Editor Plugin

Free Eclipse plugin that adds syntax highlighting, code folding, formatting, and a synchronized tree view for JSON files. Conforms to RFC 4627 and provides a syntax‑tree parser. Marketplace URL: https://marketplace.eclipse.org/content/json-editor-plugin.