HTML Formatter
Format HTML with readable indentation while keeping elements, attributes, text, comments, and document structure visible for review.
Make HTML structure easier to inspect
Compact HTML can hide nesting, attributes, text nodes, and comments when everything is placed on one line. This formatter presents a readable layout so you can review markup before using it in a page, template, email, or component.
Formatting changes presentation rather than proving that HTML is valid, accessible, secure, or compatible with a browser. Keep the original markup and compare a controlled diff after formatting.
Use a representative sample with nested elements, attributes, text, comments, and quoted characters. Treat the formatted result as a review aid and run the HTML, accessibility, and application checks required by your workflow.
Formatting is not HTML validation
HTML is a tree of elements, attributes, text, comments, and document declarations. Indentation can make parent-child relationships and closing tags easier to follow.
A formatter arranges whitespace and markup according to its parsing path. It does not prove conformance to the HTML standard, accessibility requirements, security policy, template rules, or application behavior.
Browsers may recover malformed markup differently from a formatter. Void elements, optional tags, embedded scripts and styles, entities, and whitespace-sensitive content should be checked with the target browser and build tools.
How to format HTML
- Paste a complete HTML document or supported fragment into the source field. Remove unrelated prose or programming-language wrappers from the sample.
- Run the formatter and inspect nesting, opening and closing tags, attributes, text, comments, scripts, and styles.
- Compare the result with the original. Confirm that attribute values, entity references, text content, comments, and element order remain intended.
- After formatting, run the HTML validator, accessibility checks, template tests, and browser tests required by the project.
- Remove credentials, personal information, and private markup from samples unless your handling policy permits them.
Formatting method
- Read markup structure
The tool reads elements, attributes, text, comments, declarations, and embedded regions that can be arranged for display.
- Apply indentation
Line breaks and indentation make nested elements and sibling order easier to scan. The added whitespace is presentation output.
- Preserve content
Attribute values, text nodes, comments, entities, scripts, styles, and element order must remain tied to the source. Review a diff when exact content matters.
Exact parser recovery, optional-tag handling, whitespace policy, embedded-language behavior, and error wording should be confirmed in a live engine before being described as fixed behavior.
Read the formatted result
A successful result is a readable arrangement of the supplied HTML. Confirm nesting, attributes, text, comments, entities, scripts, and element order against the source.
A failure means the documented formatting path could not handle the input. Do not infer browser recovery or an exact parser error without runtime evidence.
If a browser, validator, accessibility checker, or template build later reports a problem, investigate that separate contract. Formatting does not add semantics or security.
Common mistakes
Treating indentation as HTML validation can hide missing attributes, invalid nesting, or accessibility problems.
Changing entity references, attribute values, or whitespace-sensitive text while formatting can change page behavior.
Assuming browser recovery matches formatter output can hide differences in malformed or optional-tag markup.
Pasting private templates, tokens, or user data into a sample can expose sensitive content.
Limits and special cases
The documented capability is HTML presentation formatting. It does not guarantee standards conformance, accessibility, security, browser compatibility, template correctness, or minification.
Optional tags, void elements, embedded CSS and JavaScript, entities, whitespace-sensitive content, large documents, and parser recovery should be tested with the target tools.
Do not paste confidential production markup unless your handling policy permits it.
Examples
Format nested elements
Can a compact HTML tree become readable?
Submit the compact markup.
Child elements appear on indented lines inside main.
Keep attributes
How should an element with an attribute be reviewed?
Format the element and inspect its opening tag.
The href, class, and link text remain associated with the anchor.
Keep a comment
What happens to an HTML comment?
Format the section with its comment.
The comment stays between the parent and paragraph in the formatted view.
Preserve an entity
Can an escaped ampersand remain intact?
Format the paragraph and compare its text.
The entity remains in the HTML representation.
Keep a void element
How should an image element be shown?
Format the image and paragraph together.
The void img element remains before the paragraph without an invented closing tag.
Review a form control
Can a label and input remain associated?
Format the form controls and inspect their attributes.
The matching for and id attributes remain visible for an accessibility review.
Frequently asked questions
Does formatting validate HTML?
No. Use an HTML validator, accessibility checker, browser test, and template checks required by the project.
Will formatting change page behavior?
It should change presentation whitespace for supported input, but compare the result and test browser behavior when whitespace or parsing matters.
Are attributes preserved?
The examples keep attribute names and values. Review a diff when URLs, classes, IDs, or exact quoting matter.
Are comments preserved?
The examples treat comments as content to retain in the formatted view. Confirm behavior for your exact input before relying on it in a build.
Can it format HTML fragments?
Use a complete document or supported fragment shape. A fragment may depend on surrounding context, namespaces, or template syntax.
Does formatting improve accessibility?
No. It can make markup easier to inspect, but labels, semantics, focus order, contrast, and ARIA still need dedicated checks.
Can it repair malformed HTML?
Do not assume automatic repair. Correct the source deliberately and validate it with the browser and tools used by the project.
What should I do after formatting?
Review a diff, run validators and accessibility tests, render in target browsers, and keep sensitive data out of shared copies.