Drag-n-Drop
to upload your archive
HTML Validator
Ensure your HTML code meets web standards
Paste your HTML or open a file and our free online HTML validator checks it against the W3C standard, listing every error and warning with the exact line so you can fix them fast. It runs from your browser with no signup, and once your markup is clean you can publish the file as a live website in one click.
-
Accurate standards compliance
Our HTML Validator checks your HTML code against the latest W3C standards, ensuring that it is compliant and error-free. This feature helps you maintain high code quality, essential for cross-browser compatibility and a smooth user experience.
-
Detailed error reporting
Receive comprehensive reports on any errors or warnings in your HTML code. Our validator identifies issues and provides suggestions for fixing them, helping you improve your code and adhere to best practices in web development.
-
Secure and private validation
Your privacy is our priority. The HTML Validator processes your code directly in your browser, meaning your code is not stored on any servers. This ensures that your work remains confidential and secure throughout the validation process.
How to use the HTML validator
-
1
Paste or Upload Your Code: Enter your HTML code directly into the validator’s text area or upload your HTML file.
-
2
Validate Your Code: Click the “Validate” button to check your HTML against the latest web standards.
-
3
Review and Fix Errors: Receive a detailed report of any errors or warnings and correct them using our suggestions.
Supported file types
Open a file from your computer, drag one in, or paste your markup. The validator accepts:
.htmlStandard HTML web pages
.htmThe short HTML extension
.xhtmlXHTML documents
.txtPlain text that holds HTML
Whether you paste your markup or open a file, the Static.app HTML validator checks it against the official W3C validation engine and lists every error and warning with its line number.
Checking a different kind of file? Static.app has a matching tool:
Static.app HTML Validator vs other free online HTML validators
Every validator here checks your markup against real web standards, and the W3C Nu HTML Checker is the authoritative reference the others build on; here is an honest look at where each one fits, including where Static.app is weaker.
| Static.app | W3C Nu HTML Checker | FreeFormatter.com | CodeBeautify HTML Tools | |
|---|---|---|---|---|
| Validation engineStatic.app, W3C, and FreeFormatter all report against the same authoritative Nu engine. | W3C Nu Checker (we relay to it) | W3C Nu Checker (the reference) | Based on Validator.nu (same engine) | Viewer/beautifier, not a W3C validator |
| Standards covered | HTML5 (via Nu engine) | HTML5, SVG, MathML, RDFa | HTML5, SVG, MathML, RDFa | HTML formatting/preview only |
| Input: paste code | Yes (Ace code editor) | Yes (direct input) | Yes | Yes |
| Input: upload / open file | Yes (open + drag and drop) | Yes (file upload) | Yes (file upload) | Yes (file upload) |
| Input: validate by live URLThe W3C checker and CodeBeautify can pull a live page by URL; Static.app cannot yet. | No (paste or file only) | Yes (check a live URL) | No | Yes (load from URL) |
| Error output | Errors, warnings, line and column | Errors, warnings, line and column | Errors, warnings, line | No standards error report |
| Editor conveniencesStatic.app links each message to its line in the editor. | Click a result to jump to the line, copy report | Source view, message list | Plain result list | Copy, download, sample, beautify |
| Publish as a live websiteStatic.app is the only one that turns your validated file into a hosted website. | Yes (host on a custom domain, free SSL) | No | No | No |
| Free, no account | Yes | Yes (open source) | Yes | Yes |
| Best for | Validate, then publish the file as a live website | The authoritative reference check, including by URL | A fast paste-or-upload check on the Nu engine | Formatting and previewing HTML, not standards validation |
If you only need the definitive verdict on a live page, the W3C Nu HTML Checker is the reference and Static.app reports the same engine's results. Static.app adds a code editor that jumps you to each error and, once your markup is clean, publishes the file as a live website on your own domain with free SSL, which the pure validators do not do.
Your HTML website file deserves reliable static hosting
Select File
or drop your archive to upload
Frequently asked questions
What is an HTML validator?
An HTML validator is an online tool that checks your HTML code for errors and ensures it meets web standards set by the W3C (World Wide Web Consortium). It helps you maintain high code quality, essential for cross-browser compatibility and a smooth user experience.
Is the HTML validator free to use?
Yes, our HTML validator is completely free to use. You can access it from any device with an internet connection without any hidden costs or limitations.
Do I need to download or install anything to use the HTML validator?
Our HTML validator does not require downloads or installations. It is a fully online, browser-based tool, meaning you can start validating your code immediately without setting up any software.
How can I validate my HTML code?
You can validate HTML code with our HTML validator. Paste your HTML into the validator's text area or upload your HTML file. Click the "Validate" button to check your code against the latest web standards and receive a detailed report on any errors or warnings.
What does it mean to validate HTML?
Validating HTML means checking your code to ensure it complies with web standards and is error-free. This process helps you create code that works consistently across different browsers and devices, improving user experience and website performance.
How do you validate HTML in Chrome?
To validate HTML in Chrome, you can use Chrome's Developer Tools by right-clicking on a webpage and selecting "Inspect." Use our HTML validator for a more comprehensive validation that checks your HTML against W3C standards. Simply paste your HTML code into the tool for an instant, detailed report on any errors or warnings.
How do I check if an HTML form is valid?
To check if an HTML form is valid, you can use our HTML validator to ensure that the form's HTML structure adheres to web standards. Additionally, form validation typically involves client-side or server-side scripting (like JavaScript) to check if the user's input meets the required conditions (e.g., email format, required fields). You can validate the HTML structure using our tool, and ensure your form's functionality through scripting.
Which tool is used to validate HTML?
Our HTML validator is an excellent tool for validating HTML. It checks your code against W3C web standards and provides detailed feedback on any errors or issues. For those looking to host their validated HTML code, Static.app is a great option for static HTML hosting, allowing you to share your validated pages with others easily.
Does the HTML validator support HTML5?
Yes, our HTML validator supports all HTML versions, including the latest HTML5. Whether you're working with modern web technologies or older HTML, our validator ensures your code complies with current standards.
Can I use the HTML validator on mobile devices?
Absolutely! Our HTML validator is fully responsive and works seamlessly on desktops, tablets, and smartphones. You can validate your HTML code on the go without any issues.
Is my HTML code safe and private?
Yes, your HTML code is safe and private. Our HTML validator processes your code directly in your browser, meaning it is not stored on any servers. This ensures that your work remains confidential and secure throughout the validation process.
What kind of errors does the HTML validator check for?
The HTML validator checks for various errors, including syntax errors, deprecated tags, missing attributes, and non-compliance with W3C standards. It provides detailed reports with suggestions for fixing these errors to ensure your code is error-free and standards-compliant.
Can I learn HTML by using the HTML validator?
Yes, the HTML validator is an excellent learning tool. You can receive immediate feedback on errors and non-compliance with web standards by validating your code. This helps you understand best practices in HTML coding and improve your skills over time. The detailed error reports also guide you on how to correct issues, making it a valuable resource for beginners and experienced developers.
How do I share the HTML code I've validated?
After validating your HTML code, you can share it by copying it and sending it to others. If you want to share a live version of your validated HTML page, you can use Static.app to host your static HTML content. Static.app provides an easy way to generate a public URL to share with others.
What are the limitations of the HTML validator?
While the HTML validator is a powerful tool for ensuring that your HTML code is error-free and standards-compliant, it does have some limitations. It focuses solely on HTML validation and does not check for CSS or JavaScript errors. Additionally, the validator is designed for validating the structure and syntax of HTML, so it does not assess overall design or functionality. For complete testing, including CSS and JavaScript, you may need additional tools.
What is the best free online HTML validator, and how does Static.app compare?
The W3C Nu HTML Checker (validator.w3.org/nu) is the authoritative reference validator, and it is the best choice when you need the definitive verdict on a live URL. Static.app relays your HTML to that same W3C Nu engine, so the errors and warnings match, and it adds a code editor that jumps you straight to each flagged line plus a copy-report button. FreeFormatter.com also runs on the same Validator.nu engine but only accepts pasted code or an uploaded file. The one thing Static.app does that pure validators do not is publish your validated file as a live website on a custom domain with free SSL.
Can I validate my HTML by URL on Static.app?
Not yet. The Static.app HTML validator accepts pasted code, an opened .html file, or a file dropped onto the editor, then checks it against the W3C standard. If you need to validate a page that is already live by its address, the W3C Nu HTML Checker and CodeBeautify both support URL input. A good workflow is to validate and fix your markup here, then use the Host your HTML button to publish it as a live website.
Does Static.app use the same standards as the W3C validator?
Yes. Static.app sends your markup to the official W3C Nu HTML Checker and shows its results, so you are validating against the same HTML5 standard as validator.w3.org/nu and FreeFormatter.com. Static.app de-duplicates repeated messages and lets you click any result to jump to that line in the editor, then optionally publish the finished file as a hosted website.