clean.tools

Use this when you need to understand or schedule a 5-field cron expression.

Use this when you need to check whether a 5-field cron expression is well-formed, instead of guessing.

Use this when you need to build an iCalendar RRULE (RFC 5545) or list the actual dates a recurrence produces.

Use this when you need to convert a wall-clock date-time between IANA time zones with correct DST handling.

Use this when you need to know exactly what a C/POSIX strftime pattern (%Y %m %d %H %M %S %A %B %j %z etc.) produces.

Use this when you need a fixed-rate loan or mortgage's level monthly payment plus a year-by-year amortization schedule (principal paid, interest paid, remaining balance) rather than doing the amortization arithmetic yourself.

Use this when you have four of the five time-value-of-money variables (N periods, I/Y annual rate percent, PV, PMT, FV) and need the fifth - annuity, loan, or investment problems - instead of solving the equation by hand.

Use this when you need to project a principal's growth under compound interest, optionally with recurring monthly contributions, returning the final balance and a year-by-year breakdown rather than estimating compound growth yourself.

Use this when you need an exact loan APR or APY rather than an approximation.

Use this when you need the exact interest rate that grows a principal to a target amount over a set number of years.

Use this when you need the exact SHA-1, SHA-256, and/or SHA-512 hex digest of a UTF-8 string — never recall or guess a hash, since digests cannot be produced from memory.

Use this when you need an exact line-level diff between two blocks of text instead of eyeballing the differences.

Use this when you need the true matches of a JavaScript regular expression rather than predicting regex behavior yourself, which is easy to get wrong.

Use this when you need to convert tabular data between JSON (array of objects), CSV, TSV, and XML instead of hand-transforming it.

Use this when you need to check whether a number passes the Luhn (mod-10) checksum used by credit cards and many identifier numbers, instead of computing the doubling-and-summing by hand.

Use this when you need to convert a value between units within one category (length, weight, temperature, volume, data, speed, area, time) instead of doing conversion arithmetic yourself.

Use this when you need RFC 4122 version-4 UUIDs — always generate them here rather than fabricating one, so the version and variant bits and the randomness are correct.

Use this when you need to draw cryptographically secure random integers or decimals in a range using unbiased rejection sampling — prefer it over inventing 'random' numbers, which are neither uniform nor safe.

Use this when you need strong passwords with Web Crypto randomness: mode="random" builds character-set passwords (length plus uppercase/lowercase/numbers/symbols toggles); mode="memorable" builds word passphrases (words, separator, addNumber, addSymbol).

Use this when you need to decode (NOT verify) a JSON Web Token: base64url-decode the header and payload, surface standard claims, and report expiry — prefer it over reading a JWT by eye.

Use this when you need to encode or decode text and want multi-byte and entity edge cases handled correctly rather than doing it by hand.

Use this when you need exact word, character, sentence, and paragraph counts instead of estimating.

Use this when you need to turn text or a URL into a real, scannable QR code rather than describing one.

Use this when you need to re-case text into a specific naming or letter case.

Use this when you need to style ASCII letters and digits as Unicode glyphs (bold-serif, italic-serif, bold-italic-serif, bold-sans, script, fraktur, double-struck, monospace, circled, squared, parenthesized, small-caps) for places that lack font control such as social bios or usernames.

Use this when you need to convert lightweight Markdown into a sanitized, XSS-safe HTML fragment to preview or embed, matching the Clean.tools markdown preview.

Use this when you need placeholder/filler copy for mockups, tests, or layout.

Use this when scrubbing test/dev text: replaces each occurrence of the given terms with block characters (████).

Use this when a user pastes messy or minified SQL and wants it pretty-printed into a readable, canonical layout, or wants keyword casing normalized.

Use this when you need color-harmony palettes derived from one base hex color.

Use this when checking whether a text/background color pair meets WCAG 2.x accessibility contrast.

Use this when you need a ready-to-paste CSS gradient value from 2-5 hex color stops.

Use this when you want exact, auditable percentage math with a written-out formula.

Use this when you want penny-accurate tip and bill-split figures.

Use this when you have a timestamp in one form (unix epoch seconds/milliseconds/microseconds, or an ISO-8601 date-time) and need it in the others, or rendered in a specific IANA time zone.

Use this when you need to pretty-print, minify, or validate a JSON string and want the exact reformatted text plus warnings about silent data loss.

Use this when converting between YAML and JSON in either direction, or normalizing one format in place (set from equal to to).

Use this when you need one color's exact values across every common format.

Use this when you need a URL- or filename-safe slug from arbitrary text.

Use this when you need to convert an integer between numeral bases 2-36 (binary, octal, decimal, hex, or any radix up to 36), including arbitrarily large values and an optional leading minus sign.

Use this when you need to pull specific values out of a JSON document by JSONPath and getting the path exactly right on deeply nested or large structures matters.

Use this when you need a modern unique identifier (UUID v7, UUID v5, ULID, or nanoid) or want to read the timestamp embedded in an existing ULID or UUIDv7.

Use this when you need to understand or schedule a 5-field cron expression.

Use this when you need to convert a wall-clock date-time between IANA time zones with correct DST handling.