Need a Prize Giveaway Widget Built for a Website

We are running regular promotions for our audience and need a giveaway widget added to an existing website. The idea is simple: a visitor fills in a short form to take part, one winner is chosen at random once the promotion closes, and the result is shown publicly without anyone digging through spreadsheets by hand.

The tricky part is making the whole thing trustworthy. The random selection has to be genuinely fair and, ideally, checkable after the fact rather than a hidden script nobody can verify. We also need protection against the same person submitting several entries from one address to improve their odds, and the entry form itself should be quick to fill in on a phone screen.

Once a draw finishes, the winner announcement should appear automatically, together with a short summary of how many people took part. We would like the whole flow packaged as a widget that can be dropped into different pages without rebuilding it each time, plus clear instructions on launching a new round.

Looking for:
— a simple entry form with basic field validation
— fair random winner selection with a way to double-check the result
— duplicate-entry protection tied to the submitting address
— automatic publication of the winner and entry count
— a reusable widget that works on both desktop and mobile