XML formatter/validator

Format, minify, and validate XML instantly. Pretty-print with configurable indentation, sort attributes, add XML declarations, and catch parse errors — free, browser-based.

More free online data tools — no install required.

What XML formatter/validator Does

Format mode takes raw or minified XML and outputs a human-readable indented document with consistent spacing, optional sorted attributes, and an optional XML declaration prepended. Minify mode takes any XML and outputs a single compact string with all insignificant whitespace removed. Validate mode parses the input and returns either a confirmation with element and attribute counts or the exact parser error message pinpointing the structural fault.

Who Uses This Tool

XML formatter/validator is built for Backend developers debugging XML API payloads, frontend developers working with SVG or XML data feeds, DevOps engineers handling XML-based config and deploy descriptors, QA engineers validating XML test fixtures, data engineers processing XML exports from third-party systems. Whether you are processing data as part of an automated pipeline or need a quick one-off conversion in your browser, the tool requires no installation and no account — paste your input and get your result in seconds.

Primary Use Case

Pretty-printing a minified or malformed XML response from an API or system log to make its structure readable before debugging or editing.

The Problem It Solves

Minified XML returned from APIs, legacy systems, or log files is effectively unreadable — nested elements collapse into a single line with no visible structure, making it impossible to trace a malformed node or find a specific attribute by eye. Manually inserting line breaks and indentation is impractical beyond a few elements. At the same time, XML parse errors from development tools give vague or browser-specific messages that are hard to act on. This tool removes both problems: format produces correctly indented, visually navigable XML in one step, and validate returns the exact parser error with no ambiguity.

Example

Input
<root><user id="1"><name>Alice</name><email>alice@example.com</email></user></root>
Output
<root>
  <user id="1">
    <name>Alice</name>
    <email>alice@example.com</email>
  </user>
</root>

What to Do With the Output

They paste the formatted XML into a code editor or documentation file for readability, use the minified output in an API request body or config file where whitespace overhead matters, or act on the validation error message to fix the offending node in their source before resubmitting.

Common Mistakes to Avoid

Unescaped & characters in text content — such as ¶m=1 in a URL inside an element — cause an immediate parse error because & must be written as &amp; in XML. Attributes without quoted values and tags with mismatched case also fail since XML is case-sensitive and requires all attribute values to be quoted. The XML declaration <?xml version="1.0"?> is optional but must appear on the very first line with no preceding whitespace if present — leading spaces or a BOM before it cause a parse error in strict parsers. Minify mode removes all insignificant whitespace including whitespace-only text nodes, which changes the DOM structure and can affect applications that rely on whitespace text nodes being present.

How It Works

All three modes begin by passing the input to the browser's native DOMParser with MIME type application/xml. If a parsererror element is found in the resulting document, the error text is extracted, cleaned, and thrown as a descriptive exception — this is the validation mechanism. Format mode then walks the parsed DOM recursively, serializing each node type (element, text, CDATA, comment, processing instruction, DOCTYPE) with depth-based padding and newlines. Single-text-child elements are rendered inline. Empty elements are self-closed. Attributes are optionally sorted alphabetically. Minify mode runs the same serializer with all padding and newlines suppressed and inline whitespace collapsed. The XML declaration is added as a string prefix if the option is enabled and one is not already present.

Pro Tip

Use Sort Attributes before formatting XML that comes from multiple sources or systems — normalized attribute order makes structural diffs between two versions of the same document far cleaner and prevents false positives in version control comparisons where only attribute order changed but content did not.

Also Known As

XML formatter/validator is also commonly referred to as XML beautifier, XML pretty printer, XML minifier, XML syntax validator, format XML online, XML lint online, XML indenter, XML cleaner, XML whitespace remover, online XML checker, XML parse error finder. All of these terms describe the same conversion — no matter what you call it, this tool handles it.

Frequently Asked Questions

Format produces indented, human-readable XML with each element on its own line. Minify produces the same XML as a single compact string with all insignificant whitespace removed — useful for reducing payload size in API requests or storage.
Bare & characters in XML text content or attribute values must be escaped as &amp;. Unescaped ampersands — common in URLs embedded in XML — cause an immediate parse error. Replace every & with &amp; in the raw XML before formatting.
No. Validation checks only structural well-formedness using the browser's XML parser — correct nesting, closed tags, valid attribute syntax, and proper escaping. It does not validate against an XSD schema or DTD definition.
It prepends <?xml version="1.0" encoding="UTF-8"?> to the formatted output if one is not already present. This is optional for many parsers but required by some strict XML processors and interchange formats.
For most documents, no. However, if your application relies on whitespace-only text nodes between elements — for example, treating them as significant content — minify mode will remove them, which changes the DOM structure.
Yes. The serializer preserves CDATA sections, comments, and processing instructions through both format and minify modes. CDATA content is output verbatim without escaping its inner content.