Browser-based XML formatting and basic well-formedness checks
XML Formatter Online: Beautify XML in Your Browser
Paste XML, choose an indentation style, and turn a compact document into readable source you can review.
This free XML formatter online runs locally in your browser. It keeps tags, attributes, comments, CDATA, declarations, and namespace prefixes while adding consistent line breaks. The tool does not fetch external entities or send your XML to a formatting server.
XML formatter
Format and check an XML document
Paste XML to begin.
Maximum input: 250,000 characters. Load a sample to try the XML formatter.
Output is plain text. External entities and scripts are not executed.
How to Use This XML Formatter Online
An XML formatter makes nested elements easier to scan by placing child tags on separate lines and using a predictable indentation level. It is useful for a copied API response, a configuration file, an RSS or sitemap fragment, or a document that has been compressed into one line.
- Paste a complete XML document into the input field. The counter shows the current line and character count.
- Choose two spaces, four spaces, or tabs to match the style used by your project.
- Select Format XML. The page checks matching tags, closed comments and CDATA, and a single document element before creating output.
- Copy the formatted result or download it as
formatted.xml. Keep the original and compare changes before committing a production file.
Example: Format a Compact XML Document
Input
<catalog><book id="bk101"><title>Readable XML</title><tags><tag>api</tag><tag>config</tag></tags></book></catalog>Readable output
<catalog>
<book id="bk101">
<title>Readable XML</title>
<tags>
<tag>api</tag>
<tag>config</tag>
</tags>
</book>
</catalog>The formatter keeps the id attribute and element text exactly as source text while making the parent-child relationship visible. It does not sort attributes, rename elements, add a missing XML declaration, or convert one XML vocabulary into another.
What an XML Formatter Changes and Preserves
Formatting is a source-layout operation. It inserts line breaks and indentation around nested elements where the XML structure allows it. The output remains XML text; the page does not render the document as an application or resolve remote resources.
- Declaration and processing instructions: an XML declaration such as
<?xml version="1.0"?>remains at the top, and processing instructions are kept as source tokens. - Attributes and namespaces: attribute order, quoted values, prefixes such as
soap:, and namespace declarations are not rewritten. - Comments and CDATA: comments and
<![CDATA[...]]>blocks stay intact so embedded text is not treated as markup. - Mixed content: elements that contain meaningful text alongside child elements stay on one logical line to avoid inventing whitespace inside the text.
The basic check is intentionally narrow. It catches an unclosed tag, a mismatched closing tag, an unfinished comment or CDATA block, unclosed quotes in a tag, and more than one document element. It does not prove that a file follows a DTD or XSD, that a namespace URI is reachable, or that a service will accept the business data.
XML Formatter vs. XML Validator
| Task | What it answers | What it does not prove |
|---|---|---|
| Format XML | Can the nested source be laid out with readable indentation? | It does not validate an XSD, DTD, schema version, or business rule. |
| Check well-formedness | Do tags, quotes, comments, CDATA, and the document root close consistently? | A well-formed document can still fail an application contract. |
| Validate XML | Does the document conform to a selected grammar or schema? | This page does not fetch schemas or replace a project test suite. |
When conformance matters, use the W3C XML resources and the validator or schema tool required by your project. Formatting first can make the validator's line and column references easier to read, but it is not a substitute for validation.
XML Formatting Errors, Limits, and Privacy
Common input errors
If the result is empty, check that every opening tag has the correct closing tag and that the document has one root element. A literal ampersand in text may need to be written as &; an unescaped < inside text can look like a new tag. Keep CDATA blocks closed with ]]>, and make sure quotes inside an attribute value match.
Large documents and special syntax
The input limit is 250,000 characters. A large export can use substantial browser memory, and a complex document can take longer to format. The tool does not expand entities, download schemas, execute processing instructions, or understand application-specific extensions. For multi-megabyte files, use the formatter configured for your local repository.
Local processing
Formatting, basic checks, copying, and downloading run in this browser page. The XML source is not sent to an online formatting endpoint or stored in an account. The site still loads analytics and advertising scripts; do not paste passwords, access tokens, personal records, or other restricted data unless your policy permits that workflow.
XML Formatter Online FAQ
What does an XML formatter do?
An XML formatter adds consistent line breaks and indentation so nested elements, attributes, comments, and namespaces are easier to inspect. This page also checks basic well-formed structure before producing output.
Is this XML formatter online free?
Yes. Formatting, basic checks, copying, and downloading are available in a modern browser without an account.
Does formatting XML validate an XSD or DTD?
No. The tool checks syntax-level structure only. Use the schema and validator required by your application when you need XSD, DTD, namespace, or business-rule validation.
Does the formatter preserve XML comments and CDATA?
Yes. Comments, CDATA blocks, declarations, processing instructions, attributes, and namespace prefixes are preserved as source text while layout whitespace is organized.
Can I format an XML snippet online?
The safest input is one complete document with a single root element. A fragment with multiple top-level elements is rejected so the result does not look like a valid XML document when it is not one.
Can I format a large XML file?
This page accepts up to 250,000 characters. For larger files or repository-wide formatting, use a local tool with a checked-in configuration and test the result in your normal pipeline.
Is my XML uploaded or stored?
No. The formatter runs in the current browser page and does not send XML to a formatting API. Follow your organization's data-handling rules for any web-based tool.
Format XML Before You Review or Validate It
Use this XML formatter to make compact source readable, catch basic tag-structure errors, and create a clean file for review. Formatting helps you see the document tree; it does not replace schema validation, application tests, or source control. Keep the original input, inspect mixed content and special blocks, then choose the validator that matches your XML contract.