'forecast':1 'market':3 'platform/prediction':2

'market':4 'money':2 'play':1 'predict':3

'al':7 'austin':4 'chen':5 'develop':2 'et':6 'product':1

Forecasting platform where users can easily create markets

'creat':7 'easili':6 'forecast':1 'market':8 'platform':2 'user':4

Forecasting platform for predictions which are both serious and unserious

'forecast':1 'platform':2 'predict':4 'serious':8 'unseri':10

[No answer has any supporting data or argument in the comments]

'answer':2 'argument':8 'comment':11 'data':6 'support':5

Website with the second-level domain name 'manifold'

'domain':7 'level':6 'manifold':9 'name':8 'second':5 'second-level':4 'websit':1

Play money or charity donation, prediction and/or forecasting platform

'and/or':7 'chariti':4 'donat':5 'forecast':8 'money':2 'platform':9 'play':1 'predict':6

Prediction Market listed on the Wikipedia page for prediction markets

'list':3 'market':2,10 'page':7 'predict':1,9 'wikipedia':6

Website that thinks there is a 6% chance of a nuclear detonation in the next 5 weeks

'5':16 '6':7 'chanc':8 'deton':12 'next':15 'nuclear':11 'think':3 'websit':1 'week':17

Non-Sports-Focused Prediction Market/Forecasting Platform

'focus':4 'market/forecasting':6 'non':2 'non-sports-focus':1 'platform':7 'predict':5 'sport':3

Resolves to the most general answer that is technically, pedantically, correct.

To avoid sniping existing answers with minor improvements: if your answer is a close relative of an existing answer, it should be no less readable / no less compact than the prior answer.

I suspect I'll be making a bunch of judgment calls here; I will not bet.