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XML Formatter
XML Formatter & Validator — Free Online Tool
Format messy XML into readable, indented output with validation.
About XML Formatter
Unformatted XML is nearly impossible to read, especially when dealing with deeply nested configuration files, SOAP responses, or data feeds. This tool parses your XML using the browser's native DOMParser, validates it for well-formedness, and outputs it with proper indentation and line breaks so you can easily understand the structure. Syntax errors are clearly reported with descriptive messages and line information, helping you quickly locate missing closing tags, mismatched elements, or encoding issues. You can also minify formatted XML to a single line when compact output is needed for configuration files or API requests. Common use cases include formatting API responses from SOAP services, reviewing configuration files for applications like Maven or Spring, inspecting RSS and Atom feeds, and debugging XML payloads in enterprise integrations. The tool is also helpful for validating XML before submitting it to a parser or API that requires well-formed input.
Questions
Is my XML sent to a server?
No. All processing happens locally in your browser. No data leaves your device.
Does formatting change the XML data?
No. Formatting only affects whitespace and indentation. Element names, attributes, and text content remain unchanged.
Can it handle large XML files?
It works well for XML documents up to a few megabytes. Very large files may cause the browser tab to slow down due to parsing and rendering.
Does it validate my XML?
The tool checks for well-formedness (proper nesting, matching tags, valid syntax) and will report parsing errors if your XML is malformed.
Is my file uploaded to a server?
No. Transmute processes everything locally in your browser using JavaScript and WebAssembly. Your files never leave your device — there is no server, no upload, no cloud processing.