Network/HTTP
Break a User-Agent string down into browser, engine, operating system, and device type.
Break a URL down into its parts — protocol, host, port, path, query parameters, fragment.
Parse a URL query string into a JSON object, or build a query string back from JSON.
Generate or decode an HTTP Basic Authentication header — Base64(username:password).
Parse raw HTTP headers (from curl -I, DevTools, raw response) into a field list with descriptions and a security headers check.
Parse a Set-Cookie header or a Cookie/document.cookie string into name, value, attributes, and a check for common security mistakes.
Explain step by step whether the browser will allow a cross-origin request — simple/preflight classification, Access-Control-* response header checks, and a verdict.
Recursively sort JSON object keys alphabetically — array element order is left untouched, only object keys at every nesting level.
Check robots.txt — User-agent group structure, directives, and a path tester for allow/block decisions.
Generate PGP keys, encrypt and decrypt messages (OpenPGP, RFC 4880) via the openpgp.js library.
Compute HMAC (Hash-based Message Authentication Code) of text or a file with a secret key — eight algorithms at once: MD5, SHA-1, SHA-256, SHA-384, SHA-512, SHA3-256, SHA3-512, RIPEMD-160.
Cryptographically random passwords with configurable length and character set.
Convert a number into text (in Ukrainian, Russian, or English), with an optional currency-amount mode for hryvnia, dollar, euro, or ruble.