OnlineDeveloperTool
Text & Data

XML Validator Online

Check whether XML is well-formed and see the error if it is not.

Updated

This tool runs in your browser. No account or signup is required.

Common XML Validator tasks

Developers typically reach for this page when they need to check if XML is well formed; validate XML syntax online; find an XML parsing error. The tool is built for quick, practical work rather than a generic demo.

What matters in a xml validator workflow

When developers compare online tools for this job, the useful capabilities tend to center on well-formedness, line/column errors, file input, schema distinction. This page keeps those practical needs in mind while linking to related tools when a different workflow is a better fit.

What is XML Validator?

XML Validator parses your XML with the browser's XML parser and reports whether it is well-formed.

What problem does it solve?

Config files, exports and API payloads come in different formats, and moving between them by hand is where typos creep in.

How to use XML Validator

  1. Paste your data into the input box.
  2. Press Process.
  3. Copy the output, or read the error message if the input could not be parsed.

Example

Input

<a><b></a>

Output

Error: XML Validation Error (parser message)

What you can do with XML Validator

  • Validate XML online
  • Check XML is well-formed
  • Find an XML syntax error

Common use cases

  • Converting a config between formats
  • Checking a document before committing it
  • Turning an export into something your code can read

Related developer tasks

  • Validate XML online
  • Check XML is well-formed
  • Find an XML syntax error

What counts as valid XML here

The tool uses your browser's XML parser and reports a parser error if the document is not well-formed. That covers syntax, not meaning.

  • Every opening tag has a matching closing tag, in the right order.
  • There is exactly one root element.
  • Attribute values are quoted, and & is written as &amp;.

XML validator example

<root><item>one</root>

// Result: an error from the XML parser (wording depends on your browser)

<root><item>one</item></root>

// Result: Valid XML!

Related: XML Formatter, HTML Encoder, JSON Validator

XML Validator FAQ

What happens if my input is invalid?

You get the parser error message instead of output, so you can find the problem.

Does it change my data?

It re-reads and re-prints the same content. Only the formatting or format changes.

Is my data sent to a server?

The processing runs in your browser, so what you paste into the tool is not uploaded for processing. As with any tool, avoid pasting live secrets you cannot afford to leak.

Does it check a DTD or XSD schema?

No. It only checks that the XML is well-formed.

Looking for something else? Browse all developer tools.

onlinedevelopertool.com is a collection of 54 free, browser-based utilities for the small jobs that interrupt real work: formatting a JSON response, decoding a token, converting a timestamp, generating a UUID or checking a hash. Each tool has its own page with a short explanation, a worked example and answers to common questions, so you can use it and learn what it does at the same time.

There is no account to create and nothing to install. Tools run in your browser, so the text you paste is processed on your own device. The one exception is the Website Status Checker, which sends a request from your browser to the address you enter.

Three steps: paste your input, click the tool, copy the result, all inside your browser
Popular developer utilities: JWT decoder, UUID generator, Base64 decoder, SHA-256 hash, regex tester and timestamp converter

What you can do here

  • JSON Tools

    Format, validate, beautify and minify JSON, generate C#, TypeScript, Java, Python, Go, PHP and Kotlin models from it, or convert between JSON, YAML and CSV.

  • Encoders & Decoders

    URL, Base64 and HTML encoding and decoding, plus a JWT decoder for reading token claims.

  • Generators & Hashes

    Generate UUIDs and JWTs, validate UUIDs, and create MD5, SHA-256 and SHA-512 hashes.

  • Web Tools

    Timestamps, color codes, query strings and cron expressions - the small things web work keeps throwing at you.

  • Text & Data

    Format XML and YAML, count text, change case, make slugs, test regex, diff two texts and convert number bases.

  • Website Checking

    Check whether a website or URL is reachable from your browser.

Quick developer reference

  • JSON

    Keys and strings must use double quotes, and trailing commas and comments are not allowed. Those are the three most common reasons a payload fails to parse.

    Validate JSON

  • JWT

    A JSON Web Token is three Base64URL parts joined by dots: header, payload and signature. Decoding shows the claims but does not prove the token is genuine; only signature verification does.

    Decode a JWT

  • Base64

    Base64 is an encoding, not encryption. Anyone can reverse it, and it makes data roughly one third larger, so never use it to hide secrets.

    Decode Base64

  • UUID

    A version 4 UUID is made of random bits and written as 8-4-4-4-12 hexadecimal characters. Collisions are astronomically unlikely, which is why they work well as identifiers.

    Generate a UUID

  • Timestamps

    A Unix timestamp counts time since 1 January 1970 UTC. Ten digits usually means seconds and thirteen digits usually means milliseconds.

    Convert a timestamp

  • Hashes

    MD5 is fine for quick checksums but is not safe for security. Prefer SHA-256 or SHA-512, and remember that hashing is one-way and is not encryption.

    Create a SHA-256 hash

Missing a tool you need? Visit the contact page and tell us what you reach for most often. You can also browse every tool or read the About page to see how the site is built and what it does with your data.