my team is trying to develop a DAPP about fiat exchange rate. How to get the latest fiat exchange rate (USD/EURO etc.) accurately from external Oracles(Or are there better ways doing this)?
Are you going to store this information on the blockchain? Because it's going to COST YOU A LOT to constantly update every second the exchange rates. Or are you going to update every moment? Also I need to understand what type of fiat exchange rate do you need. Major pairs (EUR/USD, GBP/USD, etc.), minor pairs (AUD/NZD, CAD/AUD, etc.) or exotic pairs (HKD/INR, SGD, KRW, etc.).
I assume that you have asked this information for the front-end therefore an API should work. I recommend Currency Layer If you need exotic pairs, you must pay unfortunately.
Basically I found 1Forge which provides a lot of pairs for free. I registered with them and they have paid plans as well, however the free plan is satisfying enough.
They give an API key which you can use to connect and get those pairs. I used npm from their GitHub page and I played with it to see different functionalities: You can get Quotes for specific pairs
You can do Conversion of any amount from those pairs What I like most about 1Forge is that they offer the price, bid and ask. In the future it could allow you to update prices more frequently if you want. Hope that helped