It depends on your definition of decentralized exchanges. If you mean those that just run on smart contracts based on different networks such as Ethereum, Binance Smart Chain, Solana, Base etc. then they are very many. Pick what suites you.
Personally, i don't consider them as decentralized exchanges.
Like bitcoin is decentralized, same concept. but on exchange of btc / usdt, usd, eur ....
with spot trading, order-book, makers and takers .. and API , WS ..