Exchanges and Payment services

Centralized exchanges

Coinbase  – buy ETH with fiat or Bitcoin
Kraken  – buy ETH with any of the supported fiat (USD, EUR, CAD) or cryptocurrencies
Binance  – buy ETH with fiat or Bitcoin
Bity – buy ETH with any of the supported fiat (EUR, CHF) or cryptocurrencies (Bitcoin, Augur)
Gemini  – buy ETH with fiat or Bitcoin

Decentralized exchanges

What are Decentralized Exchanges?  – summary, types of DEXs and further readings
A Comparison of Decentralized Exchange Designs  – pros and cons of the three main models for designing an exchange
Decentralized Exchanges in 2019 – a recap by numbers

Uniswap  – protocol for automated token exchange that utilizes a constant product market maker model
KyberSwap  – uses an on-chain matching system to instantly convert tokens into other tokens, also provides fiat on-ramp service
Airswap  – uses an off-chain matching system called the Swap Protocol which allows users to easily swap tokens, also provides fiat on-ramp service
0x  – open protocol facilitating the decentralized exchange of tokens on off-chain order book Relayers
0x Asset Swapper  – provide an easy way for smart contracts to swap Ethereum-based tokens leveraging 0x liquidity
Oasis  – decentralized application allowing anyone to trade tokens, borrow against them and earn savings using Dai
FairDEX  – trading platform for ERC20 tokens built on the DutchX, that allows users to place bids on auctions running on the DutchX
Slow.trade  – sellers trading interface to interact with the DutchX
Summa Auctions  – cross-chain auctions featuring fast on-chain settlement, trustless and non-custodial transactions
DEX.AG  – DEX aggregator that gets you the best price for your trade across 11 different DEXes
Totle Swap  – swap ERC-20 tokens while automatically getting the best price on the DEX market
Token Store  – all the trading/settlement logic lives on chain in the smart contract and orders are stored off-chain on a private server
CoinSwitch  – trade hundreds of coins at best rates without creating an account on any exchange (include Binance, KuCoin, Bittrex, HitBTC, IDEX, Cryptopia and more)
Liquality  – cross-chain atomic swaps between Bitcoin, Dai and Ether
1inch.exchange  – split the order to several decentralized exchanges like UniswapExchange, KyberNetwork, Bancor and RadarRelay to avoid high price slippage
Shiftly  – find best prices among DEXs, compare and swap your cryptocurrencies instantly
ParaSwap  – aggregates multiple decentralized exchanges into one place and also splits orders across multiples exchanges into one optimized and secure transaction
Tokenlon  – allows you to buy and sell imBTC & other tokens via 0x-based atomic swap
IDEX  – processes orders in a centralized order book and settles the trades on-chain
EtherDelta  – processes both orders and trade settlements on-chain
Bancor  – protocol for the algorithmic market making exchange with on-chain liquidity
DDEX  – decentralized exchange built on Hydro Protocol technology, offering instant, real-time order matching with on-chain settlement
RenEx  – dark pool (OTC) exchange, where orders between buyers and sellers are private from each other, also provides decentralized cross-chain interoperability
Loopring  – decentralized exchange protocol with a hybrid order model with a focus on liquidity
DeversiFi  – hybrid decentralized exchange, allowing users to trade ERC20 tokens against ETH or USD
Shapeshift  – offers crypto to crypto trading functionality and is primarily intended to be used as an API integration, also offers to buy crypto with USD
TEX  – layer 2 commit-chain based decentralized exchange, built on top of the NOCUST commit-chain by the Liquidity Network

Other 

Dether  – global, peer-to-peer marketplace for buying and selling ETH in person with cash
LocalCryptos  – global, peer-to-peer marketplace for buying and selling ETH with over 30 supported payment methods, including in-person cash trades
DAIHard  – peer to peer crypto-fiat onramp that is unkillable, uncensorable, and globally accessible
Wyre  – exchange that offers crypto to fiat and compliance solutions via API and dashboard, also by using Apple or Google pay
Ramp  – decentralized peer-to-peer fiat to crypto trades
Wirex  – payment platform, that allows you to spend and exchange crypto & fiat currency
Dolomite  – decentralized exchange and a comprehensive portfolio manager, also fiat on/off ramp solution working directly to/from your wallet

Payment services

Coinbase Card  – Visa debit card, funded by your Coinbase balance, allows you to spend your crypto worldwide
0x Instant  – simple crypto purchasing in any app or website
Coinbase Commerce  – accept cryptocurrency payments for your business
Dexpay  – point-of-sale for physical stores and online shops that accepts Ethereum and many other coins and instantly converts them to Dai stablecoin
StablePay  – send and receive cryptocurrency payments converted to DAI
BitPay  – accept Ethereum (or Bitcoin) for online payments
Etherglade  – accept Ethereum on your site in minutes
Groundhog  – payment gateway between merchants and customers to facilitate crypto subscriptions
Daisy  – enables anyone to accept cryptocurrency for purchases, subscriptions, usage fees and other payments trust utilities
Sablier  – pay your employees continuously
BitWage  – pay salaries in Ether
Whisp  – pay remote or on-site workers in crypto