There is no "legal" way to get this data. This is how I do that:
GET this endpoint. It used for Binance SPA and does not mention in their documentation. Data is an array that contains all trading Binance pairs. For example:
"s":"BTCUSDT",
"st":"TRADING",
"b":"BTC",
"q":"USDT",
"ba":"฿",
"a":"",
"I":"0.00000100",
"ts":"0.01",
"an":"Bitcoin",
"qn":"TetherUS",
"o":"46915.84",
"h":"47499.43",
"l":"44961.09",
"c":"46791.85",
"v":"91500.82",
"qv":"4248420233.17226301",
"y":0, "as":91500.81462400,
"pm":"FIAT", "pn":"FIAT",
"cs":18620881,
"tags":["pow","mining-zone"],
"pom":false,
"pomt":null,
"etf":false
You need to take the field CS and multiply it by the current asset price. In this case, it will be field C
18620881 * 46791.85 = 871,305M
So this is the current BTC market cap