Saas:-

INVISION

Invision began as a simple prototype tool in 2011. It allowed designers to create their experience without requiring the engineering/dev team to build it, which they could then present to the engineering, product, marketing, and executive teams for discussion and/or approval. Subscriptions are how it makes money, while most offer free versions with limited features as a loss leader, or a way to persuade you to sample the software in the hopes that you’ll buy a subscription.