Cryptography
Type a secret message, pick a cipher, and watch it scramble. Every code here works both ways โ flip to Decode, paste in a coded message, and read it back out.
Pick a cipher
๐๏ธ Caesar shift โ encoded
Phhw ph dw wkh rog rdn wuhh dw qrrq
๐จ Send it to a friend โ they tap the link (or scan the code) and it decodes itself.
How Caesar shift works
Julius Caesar's own cipher: slide every letter down the alphabet by a fixed number. Shift by 3 and AโD, BโE, CโF. To read it, slide back the same amount.
More number toys
Jump into another calculator.
๐๏ธ Date Calculator
The gap between any two dates โ even billions of years.
โฑ๏ธ Cosmic You
Seconds alive, heartbeats, distance flown through space.
๐
Calendars
One day across the Gregorian, Maya, Islamic & more.
๐ข Big Numbers
How big is a billion? Every named number, written out.
โพ๏ธ Legendary Constants
ฯ, e, ฯ, โ2 & ฯ โ endless digits, spirals & digit hunts.
๐งฌ Prime Lab
Factor numbers, GCD/LCM, primality & the Ulam spiral.
๐ Speed & Distance
Light-travel times and how far to real places.
๐ Converters
Every unit at once โ length, mass, speed, data & more.
โ๏ธ Compare
You vs. a blue whale, a car vs. the speed of light.
๐ช Weight in Space
What you'd weigh on every planet, moon & black hole.
๐ป How Computers Count
Binary, bytes & how a computer stores your words.
๐ฒ Random
Random numbers, dice & coins โ with facts about every result.
๐ Probability & Odds
Birthday paradox, Monty Hall, dice curves & odds.