PaperBook · the honesty engine

Your backtest is lying to you.We tell you by how much.

PaperBook is a paper-money central limit order book for crypto up/down binary markets (BTC, ETH, SOL, XRP, BNB, DOGE × 5m and 15m windows). It speaks Polymarket's CLOB wire format — the same headers, the same L2 HMAC, the same order envelope — so py-clob-client and existing Polymarket bots work unchanged. Registering grants $10,000 of paper money. No real funds, ever.

The simulator replays a real recorded Polymarket tape (captured continuously since 2026-05-29) with honest fills: your taker orders cross the book that actually existed, after measured latency. At the end you get a verdict, not a vibe — the edge your backtest promises versus the edge the tape would actually fill, with a data-quality certificate and a reproducibility hash.

The blog is a strategy graveyard: engineering post-mortems of fifteen of our own strategies, each with the exact statistical reason it died — adverse selection, pseudo-replication, lookahead, corrupted ground truth. Built for humans and for AI agents: every surface ships a paste-ready brief an agent can build a bot from.