Check JavaScript code for syntax errors using the Function constructor. Validate code before execution. Code never leaves your device — formatting and validation run locally in your browser.
Content reviewed October 2026 · About Toolzum
Verify that a hash matches a given input to check data integrity. Code never leaves your device — formatting and validation run locally in your browser.
Validate Content Security Policy headers against W3C spec and common pitfalls. Code never leaves your device — formatting and validation run locally in your browser.
Basic syntax sanity check for JSON (full parse), XML (root-element check), and YAML (real js-yaml parse) — JavaScript not included. Code never leaves your device.
Validate IBAN structure, length, and mod-97 check digits for 80+ countries. Catch transfer typos before money moves — local ibantools work, free, no signup.
Score your resume against a job description for ATS compatibility — keyword gaps, formatting flags, and fix suggestions. Applicants lift a 52/100 resume past 80 before applying — 1 credit per check, sign in free.
Missing brackets, bad tokens, and reserved-word misuse with line numbers.
Modern ES syntax including modules, optional chaining, and nullish coalescing.
Parses fine — formatting quality is irrelevant to validity checks.
No — checking runs locally in your browser, free with no signup.
JavaScript Formatter
Format JavaScript with consistent indentation, semicolons, quotes, and brace style. Standardize legacy scripts before refactor — local processing, free, no signup.
HTML Linter
Lint HTML for missing DOCTYPE, unclosed tags, and unexpected closing tags. Paste your HTML and get instant feedback. Catch errors before browsers guess wrong — free, local, no signup.