Dream11: fifteen million people, thirty minutes after the toss

How a fantasy sports platform at IPL scale works: 15.01 million concurrent users and 308 million requests a minute, with joins and team edits packed into the 30 minutes between the toss and the deadline; capacity forecast days ahead and added an hour before, with tiered load shedding that protects team saves and joins; mega contests that take spots from sharded counters so they can't be oversold, and templates that keep small contests open; a deadline that is one state flip checked atomically by every write; live points recomputed from versioned ball records for each distinct lineup; exact ranks from half-point histograms with ties sharing a rank; and keyed ledger postings for prizes, refunds and withdrawals with 30% tax deducted on net winnings.