What are the various options available for semi automatic, automatic trading and algo trading?

Please give list of both paid and free alternatives available

Also whether they are compactible with Zerodha kite.

Thank you for sharing your knowledge

Below are the tools and utilities which can be used for automated trading:

Most of these are compatible with Nest but not Kite.

When i try to sell a iliquid option with no seller or buyer.
When i put order , just after a second i see someone order just 5 paisa below my price, if i change his price do chamge.
Same happen when buy some one place buy order just above 5 paisa.
I want to know whats this