I created this simple tool to give more transparency and credibility to giveaways in bitcointalk.
I see there are lot of giveaways here, and this tool would fit perfectly many of them.
I would to present you the "Giveaway Manager"

https://bitcoindata.science/giveaway-manager/Giveaways can now have their results easily verified.
It is also possible to save and share the results in a unique URL.
How it Works
Provably fair giveaway managerAs the
blockhash is just a number, its last 6 digits is converted to decimal using this function:
var decimal = parseInt(blockhash.slice(-6), 16);
Now we have an integer (0 to 16777215) from the
blockhash.
After dividing this decimal by the number of participants, we use the modulo operator (%) to get the division remainder becomes the
index_number.
This
index_number is applied in the participants list, to get the position of the winner.
var index_number = decimal % competitors.length;
var winner = competitors[index_number];
For additional winners, the past winners are removed from the list and one more digit is added from the
blockhash. A maximum 30 was added to avoid working with big numbers.
If you find this useful , please refer this tool in upcoming giveaways.