is there any alternative to topsteptrader that allow algorithm trading?

Define what you require for your algo?
You can use an algo with TST as long as you trade by the rules.

I agree with @RDK91

I worked on a few algo's that worked fine, and did work to make them work within the rules of TST
this is not as easy as it sounds...

The best algo's for TST are those that have many little small bites and don't run significantly against you
but isn't that the dream of every Trader ?

Also you will have to add a few thins with regards to the news events and make sure you're flat
as well as be flat before 16:10, no overnight allowed