⛏️ 2D Bitcoin Mining Simulator — Real SHA-256 Proof-of-Work Race

Each round is a single Bernoulli trial per miner with a win probability proportional to that miner's share of total attempts made before any miner succeeds. Over a small number of rounds, variance dominates and a slower miner can easily get lucky. As the round count grows, the law of large numbers pulls the observed win frequency toward the true underlying probability — which is exactly the miner's hash-rate share. This is the same reason small mining pools see "lumpy" payouts while large ones see smooth, predictable ones.

It renders the miner's most recent real SHA-256 digest as 48 four-bit nibbles. Nibbles fully inside the current difficulty's required zero-bit prefix are highlighted brightly; a nibble straddling the boundary is shown in a intermediate shade; everything after the target is dimmed. This makes it visible, hash by hash, how close an attempt came to clearing the target — most attempts fail within the very first nibble, which is exactly what a uniformly random 256-bit output predicts.

Each SHA-256 output is, for practical purposes, a uniformly random 256-bit number. The probability that it has at least d leading zero bits is 2^-d, so the expected number of attempts before a success is 2^d. Raising difficulty by one bit doubles the expected search — the same exponential relationship that makes Bitcoin's real-world difficulty (tens of leading zero bits) require specialized ASIC hardware computing hundreds of exahashes per second.

Mining pools combine many independent miners' hash rates and split the pool's block rewards proportionally to each participant's contributed share of total hashes submitted — regardless of who happens to find the winning nonce in any given block. This simulator's win-share-versus-hash-rate-share comparison is a scaled-down, directly observable version of exactly that payout principle, played out over rounds instead of real 10-minute blocks.

crypto.subtle is a standardized browser API (part of the W3C Web Cryptography specification) that exposes the browser's own, typically hardware-accelerated, cryptographic primitives directly to JavaScript. Using it here guarantees the digest is a spec-correct, industry-standard SHA-256 output — not an approximation — while also running faster than an equivalent hand-written JavaScript implementation, which matters when a simulation needs to compute many genuine hashes per second.