Developer tools: data generators, validators and converters.
Every tool runs entirely in your browser - no login and no data sent to a server. Need to scan a whole site? Create a free account and run a WCAG, SEO and font audit.
Polish PESEL number with a valid checksum. Optionally set gender and birth date.
Tax identifiers for the selected country with valid checksums (PL, USA, Germany, Slovakia, Italy, Switzerland, France, Czechia).
IBAN number with a valid MOD-97 checksum for the selected country.
Visa/Mastercard/Amex/Discover numbers that pass the Luhn check (test data).
Generate UUID v4 (random) and v7 (time-sortable) identifiers, plus NIL.
Random passwords and secrets from a secure generator (CSPRNG).
Generate N records that conform to a JSON Schema and export to JSON/CSV/SQL.
Generate placeholder text: words, sentences or paragraphs.
Check whether a JSON payload conforms to a JSON Schema. Points out errors, where they are and what to fix.
Paste a JSON payload and get a schema (draft-07) - merges array items, detects formats and required fields.
Generate TypeScript interfaces from a sample JSON payload. Merges arrays, optional fields, nested types.
Compare two JSON payloads and see what was added, removed and changed (with path).
Check text/background contrast per WCAG 2. AA/AAA rating for text and components, with preview.
Enter a cron expression to see what it means in plain words and when it runs next.
Paste JSON or YAML (auto-detected) and switch the output between JSON, YAML and CSV.
Encode and decode URLs and parse a query string into key-value pairs.
Convert an integer between bases: decimal, hexadecimal, binary, octal.
Convert text to camelCase, snake_case, kebab-case, slug and other styles.
Encode and decode HTML entities (&, <, { etc.).
Quick reference: HTTP status codes and MIME types with search.
Sign a message with a secret (HMAC-SHA1/256/384/512) - e.g. to verify webhooks.
Sign your own JWT with HS256 from a payload and secret.
See how a page looks in Google results and on social (Open Graph). Fetches meta tags from the URL.
Encode and decode text to/from Base64 (UTF-8), with an optional URL-safe variant.
Decode a JWT token - header and payload (signature is not verified).
Test regular expressions - matches, groups and replacement, live.
Convert Unix timestamps to dates and back, with timezones and relative time.
SHA-1/256/384/512 digests of any text (Web Crypto).