Hi everyone, I'm new, so I apologize for my first question. I have a formula to trade stocks that actually works better on a platform with delayed data, (15-20 minutes), or slow api feed, or whatever you call it. Any specific ideas on which one to use?
Thanks!

Unfortunately in reality you will never be offered 15min old bids/asks.

Put in other terms: You can derive orders/limits from old data, but fills are purely hypothetical
since they are systematically off from realtime bid/ask prices.

While using 15 minutes old data doesn't make sense to me it's always possible to analyze the data from 900 seconds ago and discard the real time data.

Most of the exchanges charge for real time data. But they also offer a free package which is 15 min delayed ... so you're guaranteed that the quotes you get are delayed ...