First of all, good luck on your startup. Be ready for many ups and downs.

Early in my own startup, I needed to sign a few NDA's and I had saved a copy that a consultant had me sign so I just edited that.

I recently came upon these online service you may want to check out:

https://axdraft.com/en/demo
https://www.sparqa.com/topics

I am not associated with either of them in any way.

I would also like to share what I learnt about NDA's early on. Assess carefully if and when an NDA is required and when it might become an UNNECESSARY barrier. It all depends on the kind of information that will be shared and the information value and associated possibility of misuse. Some people are averse to signing NDA's. Some will sign anything and break it at the drop of a hat.

Feel free to use my free 15 minute consultation:
http://clarity.fm/asifosman/freecallAsif