Mondo Knows
About Mondo Knows
Mondo knows things, and Mondo likes to show you what he knows.
Mondo Knows started as a library of calculators and grew into a place to play as well as work things out. Today it holds 228 calculators, 90 browser games, 900 trivia questions, 5 puzzle formats, 6 quizzes, 6 skill challenges and 1090 sourced facts. Everything is free, nothing needs an account, and none of it is stored on a server.
The idea is simple. You might arrive to work out a percentage and stay for a quick game, a daily word puzzle and a fact you did not know. The sections link to each other on purpose, so a geography quiz leads to a geography fact, which leads to a map-style calculator.
Meet Mondo
Mondo is a red panda. He is curious, tidy, and mildly obsessed with writing things down. He reads the manual, checks the arithmetic twice, and gets genuinely excited when something turns out to be more interesting than it first looked.
He is the reason this site is calm rather than shouty: no pop-ups in your way, no dark patterns, and no invented urgency. If Mondo does not know something, he says so.
How the content is made
The editorial standards behind every section.
Calculators show their working
All 228 calculators state the formula they use, and an automated test suite checks a known answer for every single one before a release. If a tool cannot produce a trustworthy answer from what you entered, it says so instead of guessing.
Trivia explains the answer
Every one of the 900 questions across 15 categories comes with a short explanation, so a wrong guess still teaches you something. Questions are written for this site rather than scraped from elsewhere.
Facts name their source
Each of the 1090 facts cites where it came from, such as NASA, NOAA, the USGS or Britannica, with a link you can check. Facts that change over time are reviewed rather than left to rot.
Puzzles show the solution
The logic round names the rule behind every sequence, the word puzzle reveals the answer, and sudoku offers hints and a mistake checker. Nothing is a dead end where you never find out why.
Games are original and described
All 90 games were built for this site. Each has its own page with the rules, the controls, the difficulty and the time it takes, so you know what you are opening before you start.
Quizzes are labelled honestly
The 6 personality quizzes say plainly that they are entertainment rather than psychological tests. The 6 challenges explain what they measure and what can throw the result off.
What is on the site
How the site is paid for
Mondo Knows is free and there is currently no advertising on it. If that changes, ads will be kept clear of game controls and quiz answers, and the Privacy Policy will be updated before any ad is served rather than afterwards.
Nothing on the site is gated, and no result is hidden behind a sign-up. If a way of paying for the site would make it worse to use, it is not the right way.
Found something wrong?
Please say so. A wrong calculator, a dodgy trivia answer or a fact that has drifted out of date is the most useful message Mondo can get, and it will be fixed rather than argued with. Write to hello@mondoknows.com or use the contact page.