Minified or generated XML often arrives as one dense, unindented block of angle brackets. This tool re-indents it into a properly nested structure, making the document's actual hierarchy visible at a glance.
The format that once ruled the web, before JSON took over
XML (Extensible Markup Language) was standardized by the W3C in 1998, building on the older SGML standard, and quickly became the dominant format for web services, configuration files and document interchange throughout the early 2000s — SOAP web services, RSS feeds, and countless enterprise systems were built entirely around XML's self-describing, tag-based structure. Its verbosity — opening and closing tags for every element, attributes, and a stricter well-formedness requirement — eventually lost ground to the more lightweight JSON for typical web API use, but XML remains deeply entrenched in enterprise software, document formats (like Microsoft Office's .docx and .xlsx, which are technically ZIP archives full of XML), and specific domains like SVG graphics and RSS/Atom feeds.
What formatting does
The tool parses your XML into its element tree structure, then re-serializes it with consistent indentation reflecting each element's nesting depth — child elements indented further than their parents, closing tags aligned with their corresponding opening tags — without altering any of the actual element names, attributes, or text content.
Where formatted XML is genuinely useful
- Debugging SOAP or legacy web service responses — many enterprise and legacy systems still communicate via XML-based web services, and formatted output is essential for tracing a specific element through a deeply nested response.
- Reading and editing configuration files — Java, .NET and various enterprise application configurations are frequently XML-based, and properly indented XML is far easier to hand-edit correctly.
- Working with RSS and Atom feeds — inspecting or debugging a syndication feed's structure benefits from clear formatting, since these documents can have deeply nested item and metadata structures.
- Inspecting SVG markup — SVG is itself an XML dialect, and formatting a minified or programmatically generated SVG file makes its structure (groups, paths, shapes) far easier to understand and edit by hand.
Frequently asked questions
Does formatting change how the XML is interpreted? No — like JSON, whitespace between XML elements is generally not significant to how a parser interprets the document's structure (with the notable exception of whitespace inside text content itself, which formatting tools are careful to preserve rather than alter).
Why does XML need closing tags for everything, unlike HTML? Because XML enforces strict "well-formedness" rules as part of its core specification — every element must be explicitly closed, exactly one root element must exist, and attribute values must be quoted — a deliberate design choice that trades HTML's historical leniency for guaranteed, unambiguous parseability across any compliant XML parser.
Is XML still relevant today, or has JSON fully replaced it? XML remains very much in active use — office document formats, many enterprise and government systems, SVG graphics, and various industry-specific data standards (like healthcare's HL7 or finance's FpML) are built on XML and show no signs of migrating away, even as JSON dominates typical modern web API design.
Further reading
W3C — Extensible Markup Language (XML) — The original 1998 W3C specification defining XML's syntax and well-formedness rules.
Wikipedia — XML — XML's history and its continued use in enterprise systems and document formats.