About this tool
The Function Graphing Calculator is a free, in-browser plotting tool that draws y = f(x) for one or more functions on an interactive canvas. Type each function on its own line and it samples the curve at pixel resolution across the visible window, mapping data coordinates to the canvas and drawing a smooth polyline. It detects large jumps and vertical asymptotes and breaks the path there instead of drawing a false vertical line, so functions like tan(x) and 1/x render correctly.
All rendering and math run locally in your browser with the Canvas 2D API and no external libraries, so nothing you plot is uploaded. Drag the canvas to pan and use the mouse wheel to zoom in or out about the cursor; the axes, gridlines and curves redraw live. Set the initial x-range with the min and max fields and press Plot — the vertical range is chosen automatically from the sampled values, and further zooming is free in both directions.
For the first function the tool also locates x-intercepts (roots) by scanning consecutive samples for sign changes and refining each bracket with the bisection method, and it reports the y-intercept f(0). Enter expressions with the usual operators, ^ for powers, parentheses, the constants pi and e, and functions such as sin, cos, exp, ln and sqrt. It captures the simple, offline slice of what tools like Desmos do.