Polymarket alternatives

Polymarket runs a prediction market platform with a CLOB API (`/book`, `/midpoint`) and a Gamma markets endpoint, fronted by Cloudflare and accompanied by a public market WebSocket. Documented rate limits sit on the order of 1500 requests per 10 seconds for the book endpoint, but the Cloudflare layer queues bursts rather than rejecting them, so a polling loop or trading bot only sees rising latency before it ever sees a 429. Builders sizing against this kind of API need two numbers nobody publishes: the real latency of the hot endpoints at a polite request rate, and what actually happens as the request rate climbs. This benchmark probes book, price and list endpoints of five prediction market venue APIs continuously from three Railway regions (us-east, eu-west, sgp), every 5 to 7 seconds over warm keep-alive connections, with a separate cold-connect probe once per minute that forces a fresh TCP and TLS handshake. Once per day per venue it runs a 60-second-per-tier ramp at rising request rates, recording added latency versus the same-hour warm baseline and any 429 or 5xx onset. Polymarket's ramp tiers are 25/50/100 requests per 10 seconds (at most 7 percent of the documented book budget) with an automatic abort the moment throttled plus 5xx responses exceed 1 percent of a 10-second window. CDN cache hits are flagged from `cf-cache-status`, `x-cache` and `age` headers and excluded from latency aggregates so no venue ranks on its CDN. The cohort competing with Polymarket includes Kalshi (documented token bucket), Limitless (undocumented limits, errors CDN cached for 4 hours), Manifold (500 req/min per IP) and Myriad (30 req/10s keyless budget, single-region Heroku origin).