XML Formatter & Validator
Format, minify and validate XML instantly. Beautify XML with configurable indentation, detect malformed markup and inspect document statistics directly in your browser.
Format, Minify or Validate XML
Beautify XML for readability, create a compact representation, or check whether an XML document is well-formed.
Shortcut: Ctrl/Cmd + Enter to process XML
XML Document Overview
Structural information is calculated whenever the XML can be parsed successfully.
Operation
Format
Indentation
2 Spaces
Root Element
—
Maximum Depth
—
XML Structure Statistics
Inspect the nodes and structures contained in the parsed XML document.
Elements
—
Attributes
—
Text Nodes
—
Comments
—
CDATA
—
Instructions
—
XML Declaration
Details from the XML declaration when one is present at the beginning of the document.
Declaration Present
—
XML Version
—
Declared Encoding
—
Document Size
Compare the input and output after formatting or minification.
Input
0
Characters
0
UTF-8 Bytes
Output
0
Characters
0
UTF-8 Bytes
XML Syntax Basics
XML follows stricter structural rules than HTML.
Matching Tags
<title>SwiftVecto</title>
Opening and closing tag names must match exactly.
Self-Closing Elements
<image src="logo.svg" />
Empty elements can close themselves using
/>.
Quoted Attributes
<book id="15">
XML attribute values must be enclosed in quotation marks.
One Root Element
<catalog>...</catalog>
A normal XML document contains one top-level document element.
Predefined XML Entities
XML defines five predefined entity references for characters that may otherwise have special meaning.
| Character | Entity | Name |
|---|---|---|
&
|
&
|
Ampersand |
<
|
<
|
Less than |
>
|
>
|
Greater than |
"
|
"
|
Double quote |
'
|
'
|
Apostrophe |
Formatting Example
Compact XML
<catalog><book id="1"><title>SwiftVecto</title><author>Michael</author></book></catalog>
Formatted XML
<catalog>
<book id="1">
<title>SwiftVecto</title>
<author>Michael</author>
</book>
</catalog>
Example of Invalid XML
XML requires strict nesting. An element cannot be closed out of order.
<catalog><book></catalog>
The
<book>
element was opened but never closed before
</catalog>.
The validator should reject this document.
CDATA Sections
CDATA sections can contain text that would otherwise require XML escaping.
<description><![CDATA[
Research & Development <example>
]]></description>
Content inside CDATA is treated as character data rather than ordinary XML markup, with the CDATA closing sequence itself being an important exception.
Well-Formed XML Is Not the Same as Schema Validation
This tool checks whether XML follows the fundamental syntax rules required for a well-formed XML document.
It does not currently validate the document against an XSD or DTD schema. An XML document can therefore be well-formed while still containing fields, values or structures that are invalid for a particular application.
XML Whitespace Can Be Meaningful
The minifier removes whitespace-only nodes commonly introduced for visual indentation. It does not deliberately trim non-empty text content.
XML applications can still assign semantic meaning to whitespace, so review compact output before using it where whitespace-sensitive content is involved.
XML Is Parsed Without External Network Requests
The interactive browser tool parses the XML locally using the browser's XML parser. It does not need to fetch external resources in order to format ordinary XML.
The PHP fallback is also configured to prevent network access during XML parsing. This is important when handling XML supplied by users.
Private Browser-Based XML Processing
XML formatting, minification, syntax checking and structural analysis are performed directly inside your browser during normal interactive use.
- No XML file upload is required.
- XML content does not need to be sent to SwiftVecto's server.
- Validation uses the browser's native XML parser.
- Element, attribute and nesting statistics are calculated locally.
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How to Format, Minify and Validate XML
Use the SwiftVecto XML Formatter & Validator to beautify XML, compress XML into a compact form or check whether an XML document is well-formed. Choose your indentation style, inspect syntax errors and review useful document statistics directly in your browser.
Overview
XML is a structured markup language used by APIs, configuration files, feeds, document formats, enterprise systems and many integration protocols. XML documents must follow strict syntax rules, including properly nested elements, matching opening and closing tags, quoted attribute values and exactly one document element. Even small mistakes can make an XML document invalid. The SwiftVecto XML Formatter & Validator provides three complementary operations. Format restructures valid XML with readable indentation. Minify removes unnecessary formatting whitespace between XML nodes where practical. Validate checks whether the document is well-formed without requiring the user to reformat it. The tool also exposes structural statistics such as element count, attribute count and nesting depth so developers can quickly inspect unfamiliar XML.
Benefits
How It Works
Paste or type XML into the input editor.
Choose Format to parse the XML and rebuild it using readable indentation.
Choose Minify to parse the XML and output a compact representation.
Choose Validate to check whether the XML is well-formed without changing the source.
The parser checks XML structure including nesting, tag closure and attribute syntax.
Formatting only succeeds when the XML is syntactically valid.
When parsing succeeds, the document tree can be inspected to count elements and attributes.
Maximum nesting depth is calculated by traversing nested elements.
The output can be copied for use in source code, APIs or configuration files.
The browser implementation uses DOMParser for local XML parsing.
The server fallback uses PHP DOMDocument with internal libxml error handling.
How to Use This Tool
-
1Paste XML into the input area.
-
2Choose your indentation style if you want formatted output.
-
3Select Format XML to beautify the document.
-
4Select Minify XML when a compact representation is required.
-
5Select Validate XML when you only need to confirm whether the syntax is valid.
-
6Review any parsing error reported by the tool.
-
7Inspect the document statistics when parsing succeeds.
-
8Copy the formatted or minified result when required.
-
9Use Load Sample when you want to test the tool quickly.
-
10Use Clear before beginning an unrelated XML conversion.
Helpful Tips
- XML is case-sensitive, so <Item> and <item> are different element names.
- Every opening element must be closed unless it uses self-closing syntax such as <item />.
- XML documents normally require exactly one root document element.
- Attribute values must be quoted.
- Reserved characters may need XML entity escaping inside text or attribute values.
- Use & for a literal ampersand in XML text.
- Use < when a less-than character is intended as text rather than markup.
- Formatting XML does not change the semantic hierarchy of the document.
- Minification should not be treated as semantic normalization because whitespace can be meaningful in some XML content.
- Be cautious when minifying XML that intentionally contains significant text whitespace.
- An XML declaration such as <?xml version="1.0" encoding="UTF-8"?> is optional in many contexts but useful for declaring version and encoding.
- Namespaces use prefixes and namespace URIs and should not be removed merely for visual simplification.
- XML validation in this tool checks well-formed syntax rather than validating against an XSD or DTD schema.
- A document can be well-formed XML while still failing a business-specific or schema-specific validation rule.
- Do not use regular expressions as the primary parser for complex XML documents.
Common Uses
Format an XML API response for easier reading.
Validate a SOAP request before sending it.
Minify an XML configuration snippet.
Find an unclosed element in malformed XML.
Inspect an XML document copied from application logs.
Beautify an RSS or Atom feed fragment.
Validate XML generated by application code.
Inspect the number of elements in an unfamiliar XML payload.
Check whether an attribute is missing quotation marks.
Format nested configuration XML.
Verify that XML contains only one root element.
Copy formatted XML into documentation or debugging notes.
Worked Examples
The following examples demonstrate how this tool can be used in realistic scenarios.
Formatting Compact XML
The compact input <catalog><book id="1"><title>SwiftVecto</title></book></catalog> can be reformatted into a multi-line tree with catalog as the root, book nested beneath it and title nested inside book.
Detecting a Missing Closing Tag
The input <catalog><book></catalog> is not well-formed because book is opened but not correctly closed before catalog ends. The validator should report a parsing error.
Self-Closing Elements
The syntax <image src="logo.svg" /> is a valid self-closing XML element and does not require a separate </image> closing tag.
XML Attribute
In <book id="15">, id is an attribute with value 15. Attribute values must be quoted in XML.
Escaping an Ampersand
The text Research & Development is not valid directly inside normal XML character data because & begins an entity reference. It should normally be written as Research & Development.
Common Mistakes
Avoid these common mistakes to achieve the most accurate results.
- Using mismatched opening and closing tag names.
- Leaving an element unclosed.
- Using more than one top-level document element.
- Forgetting quotation marks around attribute values.
- Using an ampersand directly in XML text without escaping it.
- Assuming XML tag names are case-insensitive.
- Confusing XML syntax validation with XSD schema validation.
- Removing namespaces because they appear visually unnecessary.
- Assuming minification can never affect XML text content.
- Treating XML exactly like HTML even though XML parsing rules are stricter.
- Using HTML-only entities that are not defined in ordinary XML without a suitable DTD.
- Forgetting that <br> is not a valid self-contained XML element unless written as <br /> or separately closed.
- Attempting to parse malformed XML and then trusting partial parser output.
- Assuming formatting can repair structurally invalid XML automatically.
- Using a regex-only solution to parse arbitrary nested XML.
Glossary
Definitions of the most important terms used by this tool.
XML
Extensible Markup Language, a structured text format used to represent hierarchical data.
Element
A structural XML node represented by an opening and closing tag or self-closing syntax.
Root Element
The single top-level document element containing the main XML document structure.
Attribute
A name-value pair attached to an XML element, such as id="15".
Text Node
Character data contained between XML elements.
XML Declaration
An optional declaration such as <?xml version="1.0" encoding="UTF-8"?> describing XML version and encoding.
Well-Formed XML
XML that follows fundamental syntax rules including correct nesting, one root element and valid element and attribute syntax.
XML Validation
A process for checking XML correctness. In this tool validation means well-formed syntax validation rather than XSD or DTD schema validation.
XML Formatter
A tool that restructures valid XML using indentation and line breaks to improve readability.
XML Minifier
A tool that reduces formatting whitespace to create a more compact XML representation.
Namespace
A mechanism for qualifying XML names using namespace URIs to avoid naming conflicts.
Namespace Prefix
A short prefix such as soap: associated with an XML namespace URI.
CDATA
An XML section using <![CDATA[ ... ]]> syntax to contain text that should not be interpreted as ordinary markup.
Comment
XML content enclosed by <!-- and --> that is not treated as document data.
Processing Instruction
Special XML syntax such as <?target data?> used to provide instructions to applications processing the document.
DTD
Document Type Definition, a mechanism that can define allowed XML document structure and entities.
XSD
XML Schema Definition, a schema language used to define permitted XML structure, data types and constraints.
DOM
Document Object Model, a tree representation of structured documents such as XML and HTML.
Frequently Asked Questions
What is an XML formatter?
An XML formatter parses valid XML and rewrites it with consistent indentation and line breaks to make the hierarchy easier to read.
What is an XML validator?
An XML validator checks whether an XML document follows required syntax rules. This tool checks well-formed XML syntax rather than validating against an external XSD or DTD schema.
What does well-formed XML mean?
Well-formed XML follows core XML syntax rules, including correct nesting, matching tags, quoted attributes and a single root document element.
Can this tool fix invalid XML automatically?
The formatter does not attempt to guess structural repairs for malformed XML. It reports the parsing problem so the source can be corrected intentionally.
Can this tool minify XML?
Yes. The tool is designed to provide a compact XML output in addition to formatted output.
What indentation options are supported?
The browser interface is designed to support two spaces, four spaces and tabs.
Does XML require a root element?
A normal XML document must have one document element that acts as the root of the element hierarchy.
Is XML case-sensitive?
Yes. <Book> and <book> are different names in XML.
Can XML elements be self-closing?
Yes. An empty element may use syntax such as <item />.
Do XML attributes need quotation marks?
Yes. XML attribute values must be quoted.
Why is my ampersand causing an XML error?
The ampersand begins an entity reference in XML. A literal ampersand in normal text should usually be written as &.
What is an XML namespace?
A namespace associates XML names with a URI so elements and attributes from different vocabularies can coexist without naming conflicts.
Will formatting remove XML namespaces?
No. Formatting should preserve namespaces and other semantic XML structure.
What is CDATA?
CDATA is an XML section used to contain text without treating most markup characters inside the section as normal XML markup.
Does this tool validate XSD schemas?
No. The initial XML Formatter & Validator checks whether XML is well-formed. XSD schema validation is a separate feature and requires a schema definition.
Can XML be valid without matching an XSD?
Yes. A document can be well-formed XML but still violate a specific XSD or business rule.
What is the difference between XML and HTML?
Both use markup syntax, but XML is designed for structured data and applies stricter parsing rules. HTML has its own predefined parsing behaviour and error recovery.
Can I use HTML entities in XML?
XML defines only a small set of predefined entities unless additional entities are declared through a DTD. HTML provides a much larger named entity set.
What XML entities are predefined?
XML defines &, <, >, " and ' as predefined entity references.
Does minifying XML change the data?
Removing formatting whitespace between elements is often harmless, but XML text whitespace can be meaningful. Minified output should therefore be reviewed when whitespace-sensitive content is involved.
Can this tool handle very large XML documents?
Browser memory and parser limits still apply. The tool is intended for ordinary developer-facing XML payloads and documents rather than extremely large streaming XML datasets.
Does SwiftVecto upload my XML?
The interactive XML Formatter & Validator is designed to perform normal formatting, minification and syntax validation directly inside your browser.
Is the XML Formatter & Validator free?
Yes. SwiftVecto provides this developer utility for formatting, minifying and checking XML documents.
Things to Know
- The initial version checks XML well-formedness rather than XSD or DTD schema compliance.
- Formatting requires syntactically valid XML.
- Minification should preserve the parsed XML structure while reducing formatting whitespace.
- XML declarations should be preserved when present.
- Namespaces should be preserved.
- Comments, CDATA sections and processing instructions should be preserved where supported by the parser and serializer.
- The browser implementation should use DOMParser with application/xml parsing.
- The PHP fallback uses DOMDocument and libxml internal error handling.
- Normal interactive processing is intended to happen directly inside the browser.
Disclaimer
Well-formed XML is not necessarily valid according to an XSD, DTD or application-specific schema.
Minification can affect documents where text whitespace is semantically significant, so compact output should be reviewed before production use.
Parser error wording can differ between browser engines and PHP libxml.
Extremely large XML documents may exceed browser or server memory limits.
Users remain responsible for validating XML against any external schema or business rules required by their application.
Official References
The following official resources were used when developing this tool and are useful for further reading.