How do I validate an XSLT stylesheet?

Upload your XSLT file using the form above. The validator first checks XML well-formedness, then confirms the file is a proper xsl:stylesheet, then imports it into the XSLT processor to catch compilation errors. Pick "Syntax only" mode if you just want to check whether the stylesheet is well-formed without running a transformation.

How do I test an XSLT transformation online?

Upload both an XSLT stylesheet and an XML input file, then select "Both" or "Transform". The tool runs the transformation server-side and shows you the exact output, or error messages with line numbers if the transform fails.

Does this tool support XSLT 2.0 or 3.0?

No. This tool uses PHP's built-in libxslt engine, which only supports XSLT 1.0. If your stylesheet declares version="2.0" or "3.0" you will see a clear warning. For 2.0/3.0 features you need the Saxon processor, which is not available on standard PHP hosting.

Are my files stored on the server?

No. All uploaded XSLT and XML files are written to an isolated temporary directory, processed in memory, and deleted immediately after the transformation within the same HTTP request.

Free Online XSLT Validator & Transformer

📂 Upload files

XSLT stylesheet Your XSLT file (.xsl or .xslt)

XML input file Optional — required only for transformation mode

Mode

BothSyntax check + transform

Syntax onlyIs the XSLT valid?

TransformRun XSLT on XML

Why use this XSLT validator?

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Two-phase checking

First validates XML well-formedness, then compiles the stylesheet to catch structural and namespace errors before you even run a transform.

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Live transformation

Upload XSLT and XML together to see the actual output. Perfect for verifying your templates produce the expected result.

🔎

Version auto-detection

Automatically detects XSLT 1.0, 2.0 and 3.0 and warns you if your stylesheet needs a Saxon-compatible processor.

📍

Exact error locations

Every syntax or runtime error shows the precise line and column number so you can jump straight to the problem.

🔒

Privacy first

Files are written to an isolated temp directory and deleted immediately after processing. Nothing is logged or retained.

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Free, no sign-up

No account, no email, no credit card. Open the page and validate — up to 20 times per hour.

How to validate an XSLT stylesheet online

Step 1 — Upload your XSLT file

Click the first file picker and select your stylesheet. Both .xsl and .xslt extensions are accepted.

Step 2 — Optionally add an XML input file

If you want to test the actual transformation, upload the XML document your stylesheet should process. Without it, only the syntax check runs.

Step 3 — Choose a mode

Pick Syntax only for a quick validity check, Transform to run the stylesheet, or Both to do both in one request.

Step 4 — Review the output

Valid results show a green check and the transformation output. Errors are listed in a table with severity, line number and exact message.

Frequently asked questions

XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML documents, HTML, plain text, or other formats. It is a W3C standard used extensively in data integration, publishing pipelines, and XML-based APIs.
XSLT 1.0 (1999) is the most widely supported version and runs in every browser and server library. XSLT 2.0 (2007) added sequences, regular expressions, grouping, user-defined functions and much stronger typing via XPath 2.0. XSLT 3.0 (2017) added streaming, packages, and maps/arrays. Most platforms only ship XSLT 1.0 out of the box — only Saxon supports 2.0 and 3.0 fully.
The most common reason is that the stylesheet uses XSLT 2.0 or 3.0 features like xsl:function, xsl:for-each-group, xsl:analyze-string, or sequences. libxslt (PHP's XSLT engine) only supports XSLT 1.0. Check the version="" attribute on your xsl:stylesheet root element.
Yes. Every upload is stored in an isolated temporary directory with a random name, processed in memory, and deleted immediately in the same HTTP request. We never log file content, filenames, or IP addresses linked to uploads.
To keep the page responsive we limit the rendered output to 512 KB. The transformation itself still runs to completion — only the preview is capped.