CoinMarketCap

Basics

Well known website to check out price information about cryptocurrencies. Frequented by millions of users and dozens of funds trust CMC with their exchange data.
CoinGecko competitor

Pros and Cons

Pros

Most popular website

Cons

Has a shady side when it comes to listings and advertising.

"At one point they had 3 different known scams as advertising on one page (Bitconnect, Resonance and Bitcy.biz). Other scams they gave advertising for was Ethconnect and Bitpetite (a Bitconnect clone). In the case of Bitpetite they made six-figure monthly revenues for directing traffic to the now-defunct ponzi."
From Decrypt (15-5-2020):

"CoinMarketCap has changed its exchange ranking system, just over a month after it was acquired by crypto exchange Binance. The new system now puts Binance first—and it removes previous numbers that suggested the exchange was home to skewed or potentially suspicious trading volumes."

Competition

"A number of market data websites, led by Messari, are striving to share unvarnished figures that have not been inflated. That doing so will distinguish these data platforms from CMC in the process can’t hurt either. Messari’s Onchainfx dashboard now includes a column for “Real 10” 24-hour volume – the 10 exchanges singled out by Bitwise for their honest reporting. Messari: For “true” trading volume and more accurate figures pertaining to circulating supply of crypto asssets, Messari’s Onchainfx is the market leader.

Openmarketcap: This cryptocurrency data tracker uses prices and trading volumes from trusted exchanges only in calculating average prices and total volume.

Coinpaprika: For clear data on trading volumes, plus information on price differences between exchanges, Coinpaprika has got it locked down."

Team, Funding, etc.

Has been bought (2-4-2020) by Binance, for a rumoured $400 million.
Brandon Chez; owner
Carylyne Chan: head of marketing, now (15-5-2020) chief strategy officer. Quit (31-8-2020). Both Spencer Yang, vice president of operations, growth and revenue, and Jeremy Seow, vice president of product, have also left the company within the last two weeks.

Partners

Is listed as a 'Cooperative Partner' on the website of Monero Classic (9-2019).
Affiliate partner with Changelly
Partner of Atomic Wallet (16-8-2020).
Radicle; the CMC founders are one of the backers named as an early supporter (17-2-2021).
One of the founding members of BNB's AvengerDAO (20-9-2022).