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 ..
Try Bisq which operates as a P2P exchange and is somewhat decentralized as it uses the Bitcoin network. You would need to download its application which is only available for desktops and laptops. It is slow as it uses TOR to resist censorship which is a plus point if you are privacy focused. That being said you might encounter some issues while running the application and all you need to do is to restart the application every time you encounter a stall. You can find more details about the exchange like API, etc: