XML Formatter

Tool Overview

This XML formatter helps you make XML documents clean, readable, and well structured. It takes raw or minified XML and turns it into a properly indented tree with clear nesting. It also validates the XML so you can see if it is well formed or has errors.

You paste your XML into the tool and it automatically applies indentation, line breaks, and safe escaping. You can choose the indentation size, view the formatted XML, inspect it as a collapsible tree, or compare original and formatted versions in a diff style view. The tool can also minify XML when you need a compact version.

This tool is for developers, integration engineers, QA testers, and anyone who works with XML configuration or data feeds. It is especially helpful when dealing with SOAP payloads, configuration files, sitemap or feed XML, and machine generated XML that is hard to read by hand. You do not need advanced XML knowledge, but basic understanding of tags and attributes is useful.

The main problem it solves is that XML often becomes deeply nested and unreadable when written on a few long lines or generated by systems. Poor formatting hides mistakes like missing tags, wrong nesting, or incorrect attribute values. This formatter exposes the structure so you can inspect, debug, and maintain XML more safely.

Background & Concept Explanation

XML, or Extensible Markup Language, is a text format for structured data. It represents data using tags, attributes, and nested elements. Many systems still use XML for configuration, messaging, APIs, and document formats.

An XML document must be well formed to be processed correctly. Well formed XML has one root element, properly nested tags, and matching opening and closing tags. Attribute values must be quoted and reserved characters like ampersands and angle brackets must be escaped correctly. A related operation involves validating XML structure as part of a similar workflow.

When XML is sent over networks or stored by machines, it is often minified. Minified XML removes line breaks and extra spaces. This makes files smaller but very hard for humans to read. In complex XML with many levels and attributes, it is easy to lose track of where you are in the document.

Good XML formatting adds indentation and line breaks to show the hierarchy of elements. Each nested level is indented by a fixed number of spaces. Attributes remain on the same line as their elements. Text content is preserved while unnecessary whitespace between tags is removed. This makes the tree structure of the XML easy to see at a glance.

Validation is also important. A single missing tag or stray character can make a whole XML document invalid. Browsers and parsers usually give error messages, but they are often technical and hard to match to the original file. A validator that can locate the error by line and column and show a small snippet around it saves a lot of time.

The XML formatter in this tool uses the browser XML parser under the hood. It parses your input into a document tree, then walks that tree to produce a formatted version. If parsing fails, it extracts error information and presents it in a cleaner way together with a code snippet around the error.

Key Features

• Automatic XML validation. The tool parses your XML using a strict XML parser. If the XML is well formed, it reports success. If not, it records validation errors with line, column, and a cleaned up message, so you know exactly what went wrong.
• Configurable indentation. You can choose 2, 4, or 8 spaces for indentation. The formatter uses this value when recreating the XML from the parsed tree. This lets you match your team’s style or make very deep structures more compact.
• XML declaration preservation. If your document starts with an XML declaration such as <?xml version="1.0" encoding="UTF-8"?>, the tool detects and keeps it. The declaration is placed at the top of the formatted or minified output. This is important for systems that rely on encoding or version information.
• Safe escaping of text and attributes. When formatting, the tool escapes special characters in text nodes and attribute values. It converts characters like ampersands and angle brackets into their XML escape forms. This ensures that the output stays valid even if the original text contained characters that could break XML.
• Pretty printing of nested elements. The formatter walks the DOM tree for your XML document. It prints opening tags, recursively prints child elements with extra indentation, and then prints the closing tags. Simple elements whose only content is short text are kept on one line, while complex elements get their children placed on separate lines.
• CDATA and comment handling. CDATA sections are preserved as <![CDATA[...]]> blocks in the output. Comments are preserved and shown with the same content, with proper indentation. This matters when XML contains embedded code or notes that must not be changed by formatting.
• Minify XML output. The tool can produce a compact XML string by removing whitespace between tags. It collapses spaces and newlines so that tags sit next to each other. It also keeps any XML declaration at the front of the result. This is useful when you need to reduce size for transport or storage.
• Tree view for visual inspection. When XML is valid, you can switch to a tree view instead of raw text. The tool parses the document into a nested object and shows each element with its tag name and attributes. You can expand and collapse branches to focus on parts that matter.
• Inline diff for before and after comparison. The diff view shows short previews of the original and formatted XML side by side. It lets you confirm that the formatter did not remove important content. For very long XML, it shows the first part with ellipsis, since the main goal is to compare structure rather than every character.
• Size and structure statistics. For valid XML, the tool computes basic statistics based on the formatted output. It reports size, line count, number of elements, number of attributes, and maximum depth of the tree. These numbers give a quick view of document complexity.
• AI assisted error fixing. When XML is invalid, you can ask the tool to request a fix from an AI service. The tool sends your XML and the main parser error message to a backend. If a suggestion is returned, it includes an explanation plus a proposed fixed version, and you can choose to apply it.
• Input size protection. The tool measures your input with a 10 megabyte limit. If the XML is larger, it marks the result as invalid and records a size error. This prevents the browser from freezing when huge files are pasted or loaded.

Common Use Cases

An API integrator works with SOAP responses that arrive as long single line XML. They paste a response into the formatter, choose a comfortable indentation, and use the tree view to find specific elements and values. This makes debugging response structures much simpler. For adjacent tasks, beautifying source code addresses a complementary step.

A backend developer maintains XML based configuration files. Over time, manual edits have introduced inconsistent spacing and accidental trailing spaces. The developer formats the XML and then uses the stats panel to see how large the configuration has grown, while the diff view confirms that only layout changed.

A content team manages sitemap or feed XML for a large site. They paste problematic XML into the formatter and see that it is not well formed due to a missing closing tag. The error panel shows the line and column along with a code snippet, so they can correct the file quickly.

A data engineer receives XML exports from a third party system. Before importing the data, they run the XML through the formatter to make sure it is well formed. If there are errors, they use AI suggestions to help understand what might be wrong with the structure.

A developer learning XML wants to understand nested structures. They type a small sample and watch how the formatter indents and arranges the tags. Switching to tree view then reinforces how parent child relationships are represented in text.

How to Use This Tool (Step-by-Step)

1. Open the XML formatter and look at the two main areas. The left area is for input XML, and the right area shows the formatted output and different views.
2. Choose your indentation size from the dropdown in the control bar. Select 2, 4, or 8 spaces depending on how compact or wide you want the formatting to be.
3. Paste your XML into the input panel or type it directly. You can also paste large blocks from files, logs, or network tools. The tool checks the size and will warn you if the input is too large.
4. Wait a moment while the tool processes your XML. It validates and formats the document using a debounced background task. The status bar at the top of the editor shows whether processing is still running.
5. Look at the status bar under the control bar. If it says the XML is well formed, you can switch between formatted, tree, and diff view in the output panel. If there are errors, it shows how many along with an AI Fix button.
6. Review the formatted output view first. Scroll through to see that tag nesting and attributes look correct. If you need a compact version, click the Minify button to collapse whitespace and update both input and output.
7. Switch to tree view when you need to understand structure instead of raw text. Use the arrow controls to expand or collapse branches. This is helpful for very deep XML where text formatting alone is still hard to follow.
8. Use the diff view when you want to check what changed between original and formatted XML. Click the diff option in the view selector. You will see side by side previews of before and after, which helps you verify that content is unchanged.
9. If the XML is invalid, inspect the error details section. It shows each error with a message, line, and column, plus a small snippet of the surrounding code. Use this to fix the underlying problem in your editor or directly in the input panel.
10. When errors are tricky, click the AI Fix button. Wait for the suggestion to load, then read the explanation and review the proposed fixed XML. If you agree, click Apply Fix to replace your input with the corrected version and reformat it.
11. Use the copy buttons above each panel to copy either the input or output XML to your clipboard. Paste the formatted or fixed version back into your project, configuration, or API client.
12. When you are done, click Clear to reset input, output, errors, stats, and AI suggestions. You can then start a new session with different XML.

Calculations & Logic

The formatter first checks your input size using the browser’s Blob API. It counts the number of bytes and compares that to a fixed 10 megabyte limit. If the input is larger than this, it produces a validation error and skips parsing to protect the browser. When working with related formats, formatting JSON data can be a useful part of the process.

For validation and formatting, the tool creates a DOMParser instance and parses the text as XML. If the parser returns an error node, the tool inspects the error message, extracts line and column numbers when available, and cleans away extra browser text so the message is easier to read. The result object stores these values as validation errors.

When XML is valid, the formatter walks the DOM tree starting from the document element. For each element, it builds a string with tag name, attributes, and properly escaped text content. It uses the current depth in the tree and the chosen indent size to calculate the amount of leading space on each line.

Text nodes are trimmed to remove leading and trailing whitespace. If an element only has simple text and no child elements, the text is printed on the same line as the tags. If it has child elements or complex content, the formatter places each child on its own line and adds closing tags on a new indented line.

CDATA and comment nodes are handled separately. CDATA blocks are printed as <![CDATA[...]]> with current indentation. Comments are printed as <!-- ... -->, also respecting indentation. This keeps special content intact while still aligning it with surrounding elements.

Statistics are calculated by parsing the XML again inside the stats helper. It counts the total number of element nodes and sums the number of attributes across all elements. It also computes maximum depth by walking the tree and updating a depth counter whenever it enters a deeper level. Size and line count are derived directly from the formatted string. In some workflows, formatting YAML is a relevant follow-up operation.

AI suggestions are generated by sending the input XML and first error message to a backend service. The tool expects a JSON string containing an explanation and a proposed fixedXml. It parses this JSON and stores it until you either apply the fix or dismiss it.

Tips, Limitations & Best Practices

Always make sure you are working on a copy of important XML files. Even though the formatter tries to preserve content, it is safer to format a copy and then replace the original once you have verified the result.

Use indentation sizes that make sense for your documents. For very deep XML, 2 spaces per level reduce the width and keep lines visible. For shallow but wide XML, 4 spaces may make elements easier to scan.

Keep in mind that this formatter focuses on well formed XML. It does not check against XML schemas or DTDs. That means it can tell you whether the structure is valid, but not whether the content matches a specific contract.

When you see an error, read both the message and the snippet. The cleaned message gives a plain description, while the snippet shows the actual context with line numbers. Together they usually make it clear what needs to be fixed. For related processing needs, formatting CSV data handles a complementary task.

Use tree view when you are analyzing or designing XML formats. The tree makes the parent child relationships and repeating elements easy to see. It is especially useful when working with complex namespaces and nested lists.

Do not rely only on minified XML for long term storage when humans need to work with the files. Minified XML is harder to review and debug. Use formatted XML in your repository and minify only when sending over the network.

Treat AI fixes as suggestions and verify them closely. While AI can be helpful in pointing out missing tags or wrong nesting, it does not know the business rules behind your data. Make sure any change still matches your schema and expectations.

If you work with extremely large XML files close to the size limit, consider splitting them into smaller pieces for manual review. The formatter helps with readability, but browser memory and performance are still limited.

Remember that keyword and tag names are case sensitive in many XML based systems. The formatter does not rename elements or attributes, so any naming mistakes must be fixed manually or with other tools.

After formatting XML that is used by external systems, always run a quick end to end test. This confirms that no hidden issues such as wrong encoding, unwanted whitespace changes inside text nodes, or copy paste errors were introduced during editing.