GP will work with all well coded plugins.
From user Feedback:
Gravity forms is the most powerful and extensible – if you need advanced settings and conditions.
For more standard needs a lot of users go for Ninja Forms or WPForms.
a while back tom wrote that this page uses contactform7.
But in more recent answers the whole gp team more talks of ninja form and others.
Is the contact form on this page still contact form 7? Or did you switch? If so – why?
Also in one article it is mentioned that you use contact form 7 in the site library. Is that true?
Is there an overview which plugins you use for the site library somewhere?
GP uses NinjaForms nows – i think its mainly due to performance reasons.
Most sites that had forms got moved to Ninja > then Happy Forms > then Happy Forms messed up and we either moved back to Ninja or removed them entirely.
So i guess the article mentioning e.g. prime from site library using contact form 7 is outdated then.
i am currently trying out contact form 7 and gutenblock forms (https://wordpress.org/plugins/forms-gutenberg/) – which i found by accident (due to its name it doesnt really show up when you search for form plugins/block and looks really promising. The other contact forms available as block (coblocks, jetpack, getwid) – are rather rudimentary (name, email, message) – but gutenblock forms is more specialised. So after a little testing a viable alternative – and also open source.