TLS ECH (Encrypted Client Hello) visually explained
An visual walkthrough of TLS ECH. See why SNI leaks which site you visit, and how Encrypted Client Hello hides it using HPKE, split-mode proxying, and a clever retry mechanism.
Growing SWE
Interactive explorations of computer science and software engineering
Latest posts
Points on a Circle
A walkthrough of a popular math problem. Drop N random points on a circle. What is the probability they all land in a semicircle? The answer uses mutual exclusivity in a surprising way.
MicroGPT explained interactively
Walk through Karpathy's 200-line GPT from scratch. Tokenize names into integers, watch softmax convert scores to probabilities, step through backpropagation on a computation graph, explore attention heatmaps, and see a tiny model learn to generate plausible names.
An interactive intro to Elliptic Curve Cryptography (ECC)
A hands-on introduction to elliptic curve cryptography. Start with curve geometry, build point addition and scalar multiplication, see why ECDLP is hard, and then use that math in ECDH, ECDSA, and ECIES.
How LDAP Works: An Interactive Guide
An interactive exploration of LDAP. Build a directory from a flat list, discover tree structure, distinguished names, schemas, search operations, and authentication.
What exactly is a file format? An interactive guide
An interactive guide to various file formats. See that files are just bytes, discover magic numbers, encode characters as bits, paint pixels as hex, walk through ZIP anatomy, and watch the OS decide what a file really is.
An interactive intro to quadtrees
An interactive exploration of quadtrees. Start with brute-force spatial search, build recursive space partitioning step by step, then use it for point lookups, range queries, nearest-neighbor search, collision detection, and image compression.
How you invent math: Building numbers from nothing
An interactive journey through number system construction. Start with nothing and build natural numbers, integers, rationals, reals, and complex numbers, one crisis at a time.