XML Formatter & Validator
Pretty-print, minify, and validate XML with configurable indentation, attribute formatting, and well-formedness checks
Interactive tool
XML input
No XML to process
Paste XML or drop a .xml file to format, minify, or validate
What is an XML Formatter & Validator?
An XML formatter pretty-prints raw XML with proper indentation and line breaks for human readability. The validator checks well-formedness: matched tags, valid attributes, single root, and proper escaping. Together they keep your XML clean and catch syntax errors before they reach production parsers.
How to Use This XML Formatter
- 1Paste XML or drop an .xml file onto the input area
- 2Choose Format to pretty-print, Minify to compact, or Validate to only check well-formedness
- 3Pick indentation: 2 spaces, 4 spaces, or tabs
- 4Review validation results and any errors with line numbers
- 5Copy or download the result
Key features
Pretty-Print Formatting
Indented XML output with consistent spacing for easy reading and review
Minify Mode
Strip whitespace and compact XML for transmission and storage efficiency
Well-Formedness Validation
Catch missing closing tags, invalid attributes, and broken nesting with line and column references
Configurable Indentation
2 spaces, 4 spaces, or tabs to match your team conventions
Attribute Preservation
Attributes are kept in original order with their values intact
Comment Preservation
XML comments survive formatting and minification
Size Comparison
See input vs output bytes and percentage reduction at a glance
100% Private
All processing runs in your browser. Nothing is uploaded
Why Format and Validate XML?
Even though JSON dominates new APIs, XML is still the backbone of SOAP services, configuration files, RSS feeds, sitemaps, OOXML documents, SVG, and many enterprise integrations. A single malformed character can crash a parser. A formatter makes diff and review easy; a validator surfaces errors with exact line numbers so they can be fixed quickly.
Common use cases
- Beautifying minified XML returned from APIs
- Preparing config files for human review
- Catching syntax errors in RSS, Atom, and sitemap files
- Reviewing SVG markup before committing
- Inspecting SOAP envelopes during integration debugging
- Auditing OOXML and DOCX internal XML
- Preparing fixtures for unit tests
- Comparing XML diffs in pull requests
Format vs Minify
Format adds line breaks and indentation. Minify strips them and concatenates. Format wins for human review; minify wins for transmission size. Use format during development, minify before storing or shipping over the wire when XML is large.
Validation Beyond Well-Formedness
This tool checks well-formedness, the basic syntactic rules of XML. It does not validate against a DTD or XSD schema, which require separate inputs. For schema validation, use a dedicated XML toolchain. Well-formedness is the right first gate for almost every issue.
Tips & best practices
Validate before posting
Many APIs reject malformed XML with cryptic 500 errors. Run validate first to catch the actual issue
Minify only at the boundary
Keep formatted XML in source control. Minify only when serializing for transport
Watch for XML declarations
Always include <?xml version="1.0" encoding="UTF-8"?> at the top for production XML, especially for SOAP and OOXML
Mind CDATA blocks
Content inside CDATA is not parsed. Formatting preserves CDATA but never reformats its contents, which is correct
Use tabs in tab-indented projects
Match the surrounding code style to keep diffs minimal in version control
Privacy & security
This XML formatter and validator runs entirely in your web browser using the fast-xml-parser library. Your XML data is never uploaded to any server, stored anywhere, or transmitted. All processing happens locally on your device.
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Frequently Asked Questions
What is XML well-formedness?
Well-formedness is the basic XML rule set: every element has a matching closing tag, elements are properly nested, attribute values are quoted, and there is exactly one root element. Well-formed XML can be parsed by any XML parser, even without a schema.
Does this validate against a DTD or XSD schema?
No. The validator checks well-formedness only, which is the right first gate for almost every parsing issue. Schema validation against XSD or DTD requires the schema document itself and is best done with a dedicated XML toolchain.
Why does my formatted output look different from the input?
Whitespace between elements is reformatted, attribute spacing is normalized, and self-closing tags may be expanded or contracted depending on settings. The semantic content (elements, attributes, text) is unchanged.
Can I format SVG with this tool?
Yes. SVG is a flavor of XML and benefits from formatting and validation. Pretty-printed SVG is far easier to review in pull requests, and the validator catches typos that would cause silent rendering bugs.
How is XML different from HTML for this tool?
XML requires strict closing tags and quoted attributes; HTML is more forgiving. This tool follows XML rules. HTML5 documents may not parse cleanly here. Use a dedicated HTML formatter for browser markup.
Is my XML uploaded anywhere?
No. The formatter and validator run entirely in your browser using the fast-xml-parser library. Your XML data is never uploaded, stored, or transmitted to any server.