About this utility

About the JSON / XML Formatter and Validator

This page explains what the formatter does, how it uses your browser’s built in parsing features, and how to use it safely when you are working with API responses, logs, or sample data that might mirror production systems.

▶ Open formatter tool

What this tool actually does

The JSON / XML Formatter and Validator takes structured text that you paste into the page, checks that it is syntactically valid, and, when possible, returns a clean, indented version that is easier to read. Everything happens locally in your browser window without sending data to a server.

Two formats, one simple workflow

Many people work with JSON and XML every day. They see them in API responses, logs, configuration files, and exports from other tools. When the data is minified or slightly broken, it can be difficult to understand at a glance. The formatter gives you a simple way to:

  • Validate that the text actually counts as well formed JSON or XML.
  • Reflow it with indentation so nested structures are obvious.
  • Copy the cleaned version into other tools, documentation, or test cases.

How JSON mode works

In JSON mode, the tool relies on the native JSON engine built into your browser. It behaves the same way that a modern JavaScript application would behave when it parses JSON from an API.

  • First it calls JSON.parse() on the input and waits for a success or a syntax error.
  • On success it uses JSON.stringify() with indentation to produce a nicely formatted version.
  • On failure it surfaces the error message from the parser to help you locate the problem.

This means the tool enforces strict JSON rules. It does not accept comments, trailing commas, or single quotes around keys, which helps you catch subtle issues before data reaches production code.

How XML mode works

In XML mode, the tool uses the browser’s XML parsing and serialization features. The browser tries to turn your text into a document tree and reports any problems it encounters along the way.

  • The input is fed into DOMParser with the application/xml content type.
  • The tool then checks for a special internal element that browsers create when the XML is not well formed.
  • If parsing succeeds, it uses XMLSerializer and a simple indentation function to show the structure clearly.

This approach is ideal for quick checks such as confirming that tags are properly nested or that you have a single root element. It is not meant to replace full schema validation with XSD or Relax NG.

Typical ways to use this page

The formatter is designed for quick, everyday tasks that help reduce friction when you are working with structured text.

  • Cleaning up JSON from an API response before adding it to documentation, tickets, or an incident report.
  • Validating small XML configuration snippets before you commit them or share them with a team.
  • Inspecting sample data from training materials, blog posts, or vendor portals without relying on an online third party service.
The page does not store or log what you paste. Once you navigate away or close the tab, the content is gone. If you are working with very sensitive production data, consider masking or redacting values before using any tool, even one that runs locally in your browser.
! Legal and usage notice
This JSON / XML Formatter and Validator and this explanation page are provided for convenience, training, and basic syntax checking. The tool runs entirely in your browser, does not send your input to any remote server, and does not create lasting logs of the data you paste. It simply uses built in browser parsing features to validate and reformat structured text.

Important. This tool does not replace full testing, schema validation, security assessment, or code review. It cannot guarantee that your data model, applications, or integrations are correct, compliant, or safe. You are solely responsible for how you use the tool, what you paste into it, and how you handle any formatted output. No warranty of any kind is provided.