OPRA
The Options Price Reporting Authority (OPRA) is the official source of U.S. options prices. It collects every trade and quote from all U.S. options exchanges and distributes them as one consolidated feed.
What it is
OPRA is a plan run jointly by the U.S. options exchanges under rules of the Securities and Exchange Commission (SEC). Its securities information processor gathers the last sale, best bid and offer, and daily open interest of every exchange-listed option and publishes them in one feed. Brokers and data vendors redistribute that feed; they do not create the prices themselves.
How Mellow uses it
Mellow reads OPRA option prices and open interest through a licensed market-data provider. Implied volatility and gamma exposure are calculated from those official numbers — no estimates from social media, surveys or paid "order-flow" opinions.