Edit distance between strings.
Unix seconds ↔ ISO timestamp.
Line‑by‑line diff viewer.
Encode/decode International Morse.
Simple cipher transforms.
Generate RFC 4122 UUID v4.
Convert CSS HWB to RGB.
Search MDN named colors list.
Convert between RGB and CMYK.
Convert color temperature to sRGB.
Click‑to‑Chat link (wa.me).
Ethereum payment URL (EIP‑681).
Bitcoin payment URI (BIP‑21).
Compact contact card (MECARD).
Encode any text or link into a QR.
Check if a sentence uses all letters.
Flesch–Kincaid, Fog, SMOG (approx).
Simple web metronome (Web Audio).
Create multiple labeled countdowns.
Inspect URL parts and query params.
Sort, unique, trim lines of text.
Test JavaScript regular expressions.
Convert between CSV and JSON.
Compute sRGB relative luminance (WCAG).
Color difference (CIEDE2000).
Generate a color ramp from a base color.
WCAG contrast grid for many colors.
tel: opens dialer (RFC 3966).
sms: opens SMS composer (platform‑dependent).
mailto: email QR (RFC 6068).
geo: latitude/longitude QR (RFC 5870).
Is it a palindrome?
English letter points.
Count words and sort by frequency.
Alternate work/rest for N rounds.
Count down to duration or time.
Start, stop, reset, laps.
Find/replace with RegExp support.
Base64 ↔ UTF‑8 text.
Make clean slugs; URL encode/decode.
Uppercase, lowercase, Title, sentence.
Complement, triad, analogous.
Mix two colors (linear sRGB option).
Convert HEX and HSL.
Calendar event in a QR code.
Contact card as a QR code.
Join a Wi‑Fi network with a scan.
Surface area and volume.
Right circular cylinder formulas.
Compute GPA from course credits and letter grades (unweighted).
Convert between mpg (US/Imp), L/100 km, and km/L.
Estimate body fat using the US Navy circumference method.
Mifflin‑St Jeor BMR and estimated daily calories by activity (TDEE).
Standardize a value given μ and σ.
Population or sample standard deviation.
Solve ax²+bx+c=0.
Decimal ↔ scientific (E) notation.
Convert between decimal and fraction, reduced to lowest terms.
Convert margin and markup; compute price.
Units and sales needed to cover fixed costs.