https://fivesecondtest.com/
Optimize the clarity of your designs by measuring first impressions and recall.

How do they work?
Participants are given five seconds to view a design, after which they answer some simple questions. Before the test starts participants are given a primer on the format and reminded to pay close attention. Depending on the goal of the test, they may also be given some context for what to look out for.

Test now : https://app.usabilityhub.com/users/sign_up