Btw Zerodha has its own Api too, which has all the features needed for auto/algo trading from any third party charting software and also through Excel. But it costs 2k pm. Hence if Nest Plus API though gives some lesser features (can code missing features and use it), which cost less than 300 pm will certainly be preferred alternative.
What you is say is correct, but look at it this way, its Omnesys whose done all the work that actually takes care of everything.
== Just as an example below=== Facts might be different
Type 1: Lets say Sharekhan has enough funds to setup its own IT, Infra and entire trading platform. Therefore, they make rules and they can customize directly in their platforms.
Type 2: Discount brokers
Omnesys has created everything, including years of research etc.
Now Disc brokers start popping up, they don't have time/funds to re-invent the wheel.
On the other hand, Omnesys is willing to
resell/rent/whitelabel, teir solution for a fee that broker is willing to pay on a time period basis, say monthly.
Its just like renting a house vs buying one.
== Just as an example above=== Facts might be different
All the underlying API etc will be either linked so it works on NEST etc or Brokers Firms will invest into their platforms like Pi/kite but those API's will be wrapped around the original Omnesys API.
That's why if you see the format of Pi, it's layout maybe different but fields are exact like NEST.
Now, at least its cleat that you need individual API subscriptions if you want to route orders through multiple accounts.
(Just curious, you want to save tax etc, whats the purpose of multi a/c's)
Now, I've not interacted with Omnesys but as you say, difficult to get support(if they even offer) or scoot you to your broker.
Broker also pays Omnesys for API, the extra inr. 300 is their charge for support, maintenance etc
If you can pay support charges etc, then contact Omnesys and get a solution there and continue the NEST API.
