XPath Tester

Unsupported input

The tool may reject input that does not match the expected content, structure, or file type.

Fix: Confirm the tool input requirements and paste the correct type of data.

Incomplete values

Missing fields or partial content can block processing or produce weak results.

Fix: Provide the full required input before running the tool.

Copying placeholder content

Sample or placeholder values can lead to output that looks valid but is not ready for real use.

Fix: Replace placeholders with your actual values before relying on the result.

Does XPath Tester work without an internet connection?

Yes. Once the page has loaded, all processing is client-side — you can pull the Wi-Fi cable and XPath Tester keeps working for the rest of the session.

What regex flavor does XPath Tester use?

XPath Tester uses the JavaScript (ECMAScript) regex engine, which is ~99% compatible with PCRE for common features (character classes, quantifiers, groups, backreferences). Features unique to PCRE (e.g., recursive patterns, possessive quantifiers) aren't supported and the tool flags them on paste.

How large an input can XPath Tester handle?

XPath Tester comfortably handles inputs up to ~5 MB (roughly 50,000 lines of code or a large JSON file). Beyond that, in-browser highlighting can get sluggish — split the input or use a CLI tool for multi-gigabyte workloads.

Does XPath Tester highlight matches in real time?

Yes. Matches are highlighted as you type, and the match count plus capture groups update on every keystroke. For very long inputs, highlighting is debounced to keep typing responsive.

What diff algorithm does XPath Tester use?

XPath Tester uses the same Myers diff algorithm that git uses under the hood, so the output lines up with what you'd see in a git diff. Line-level and character-level modes are both available.