Proof over promises
Hire web app developers who show working functionality
Web applications are judged on whether the logic actually works — state, data flow, edge cases, and how the interface holds up under real use. That is very hard to assess from a case study.
How the challenge works for this category
Each of the three developers you invite builds a genuinely working piece of your application in 24 hours — a core flow, a key screen, or a critical interaction — using the stack you specify, so you can see how they actually handle the problem.
A working core feature or user flow from your app
A short demo video showing the feature in action
A written plan for how the rest of the app gets built