Validators

Validate syntax, evaluate paths, check redirects and links, or compare two files before they reach production. This category includes YAML and JavaScript validators, HTML linting, Regex Tester, JSON Path and XPath evaluators, JSONPath Finder, Redirection and Link checkers, and Diff Checker—all in your browser with nothing uploaded.

YAML Validator

Validate YAML syntax with precise line and column errors.

JavaScript Validator

Check JavaScript syntax without executing your code.

Regex Tester

Test regex patterns against sample text with match offsets and capture groups.

JSON Path Evaluator

Evaluate JSONPath expressions against JSON documents.

XPath Evaluator

Evaluate XPath against XML or HTML in your browser.

HTML Validator

Structural HTML lint - unclosed tags, duplicate ids, and common issues.

Redirection Checker

Check URL reachability and redirect hints from your browser.

Link Checker

Bulk-check links extracted from HTML or a URL list.

JSONPath Finder

Find JSONPath expressions for a key or value in JSON.

Diff Checker

Compare two text or code files side-by-side or unified.

Frequently Asked Questions

How is a validator different from a formatter?

Validators focus on correctness and error location. Formatters rewrite whitespace for readability.

Do you run JavaScript I paste?

No. The JavaScript Validator parses only—never eval.

What is Diff Checker for?

Diff Checker compares any two text or code blocks in a GitHub-style split or unified view. For LLM prompt rewrites specifically, use Prompt Diff Checker under AI tools.