Hotspot 3D
hotspot3d.com
Two products, side by side, in 3D at true size
Practical MagicA minuteFree, no sign-up
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Practical Magic
A graphing calculator that keeps up with your typing
desmos.com
A minute · Works anywhere
Free, no sign-up · online since 2011
Type an equation and the curve appears immediately, with a slider generated automatically for any variable you introduce. It handles inequalities, regressions, parametrics and tables, and renders smoothly enough to drag a parameter and watch the shape move in real time.
Adding a stray letter to an equation spawns a slider for it without being asked, which turns a static plot into something you can push around.
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Picked for a shared category and overlapping vibe, not for popularity.
hotspot3d.com
Two products, side by side, in 3D at true size
tineye.com
Find where an image came from, not what it shows
wolframalpha.com
Ask a question with numbers in it, get worked steps
photopea.com
Photoshop, running in a tab, opening your PSD files
audiomass.co
Trim and edit audio without installing anything
excalidraw.com
Diagrams that look hand-drawn, shared by one link