Desmos Graphing Calculator
desmos.com
Type an equation and watch the curve, with a slider for every parameter
No sign-upOn device
Loading page
wikipedia.org
Gets you oriented on almost any subject, with the sources listed at the bottom.
Sixty-odd million articles across three hundred languages, written and argued over in public, with the edit history and the talk page available when you want to see how contested something is. The right way to use it for anything serious is to read the article for orientation and then follow the references, which is where the citable material lives. Article quality tracks how many people care about the topic, so a physics stub and a film plot summary are not the same object.
Questions
Works the moment the page loads. No account, no email, no trial. Quality varies enormously by topic and language, and it is a starting point rather than a citable source.
Yes. Wikipedia sends your input to its own servers to process it. That is fine for public material; for anything containing personal data, use one of the on-device tools instead.
Quality varies enormously by topic and language, and it is a starting point rather than a citable source.
Alternatives
Same category or same task, ordered by how closely they overlap.
desmos.com
Type an equation and watch the curve, with a slider for every parameter
ocw.mit.edu
Publishes the real lecture notes, problem sets and exams from MIT courses
monkeytype.com
A typing test you can tune to the exact words, punctuation and length you want
musictheory.net
Free lessons and endless drills for notation, intervals, chords and ear training
openstax.org
Peer-reviewed university textbooks you can read online or download as PDFs
wolframalpha.com
Answers a maths, science or unit question typed as an ordinary sentence