About the Recursion Tree Visualizer

Watch the actual call tree of a recursive function build itself, step by step.

What it is

Pick factorial, naive Fibonacci, or binary search, choose an input, and the tool builds the real call tree in actual call order (pre-order calls, post-order returns), rendering it as an SVG diagram you can step through.

Features

Preset functions

Factorial, Fibonacci, and binary search, each with a sensible input cap.

Step-through animation

Play, pause, or step call-by-call through the actual execution order.

Call-stack depth

Each node is labelled with its recursion depth.

Call-count comparison

For Fibonacci, the exponential call blow-up is contrasted with an iterative count.

Ready to use it?

Free, no sign-up required.

Open the Recursion Tree Visualizer