Kickback at #ETHNY, lessons learnt

May 28 · 5 min read

In the , we did some analysis about our registration status. Now that the event is over, we have full data and let’s revise what happened .


The event became full just several hours before the start of the event. You can see some last minute FOMO RSVPs towards the end.

One interesting observation in the graph is the gap of historical and USD value of ETH price(green and black). The ETH price surged from $165 to $263 during the registration period. We had 45 ETH on the smart contract at one point which value shifted from $7,425 to $11,835 and individual commitment value (0.15 ETH) from $24 to nearly $40. Suddenly our “skin in the game” system turned high stakes (and from smart contract security perspective it also increased security risk which may be another reason for supporting DAI to minimise it)!


Everybody was greeted and checked in at registration in exchange for this cool floppy disk badge.

The check-in info was all kept on paper then manually entered into Kickback’s system throughout Saturday. To recap, when volunteers click “mark as attended” for each attendee, it just goes into our database. It’s only when the contract owner press “finalize”, all the information goes into blockchain and the decision becomes irreversible.

By the time all the data was into our system, it was past 10pm. At this moment we already knew that we had almost 80% attendance (which is really high!)

To make sure we hadn’t missed anyone who did check in, I sent out the following email to about 30 people who were not marked as attended yet.

For those who were in the middle of hacking, it was a bit of distraction and we got this seemingly annoyed response. Sorry about that!

In addition to relying on participant to turn up the check in desk, I also checked-in a few people who I actually talked to but didn’t check in.

I also looked into Hackathon submissions and matched up a few people assuming that if they manage to submit, they are more likely that hacking.

I also noticed a few people who weren’t even invited to hack but just sneaked in for the networking opportunity. I sent out the following people and I don’t think these people did declare themselves. Thank you for your contribution!


Throughout the hackathon, I got an enquiry about “how do I get my ETH back” so I had to explain over and over that they will receive an email.

To give participants relief, we finalised at 10:30 when the hack submission was complete. The result was… 92% of people turned up! Most hackathon tend to have 50% turn up rate so I think we did pretty well!

In addition to the extra 0.012 ETH as a kickback, all the participants should have been airdropped this cool “Proof of Attendance” by POAP team.

Kickback has been working closely with POAP team from the inception during ETHDenver.

Cooling period

As soon as people received an email to be able to withdraw their kickback, people rushed to withdraw.

To my surprise, 50 / 300 people haven’t withdrawn 7 days after the event. I sent final reminder to these 50 people that . However, there are still 40 people how haven’t withdraw. We are also aware that some people struggling to withdraw due to some errors. When I last checked, there were about 40 failed transactions from 13 different accounts. Most of them eventually managed to withdraw but we are aware that at least 3 people are still having issues. We are still investigating if there are any bugs on either our frontend or smartcontract.

We also had a few replies that they are on travel without access to their account which they used to RSVP so they won’t be able to withdraw on time.

There was one unique case that the user’s account was compromised (the reason not related to Kickback) hence there will be a bot watching his account and snatch his ETH as soon as he tries to withdraw.

Our system is actually built to cover such scenario. What happens after the cooling period is that the event contract owner (Kickback for ETHNewYork) can clear all the remaining funds and can decide what to do with it. In the past, we either sent to the organiser if they paid for our service, kept it ourselves to use for further development of the platform (which caused some negative responses in the past) or sent it to charity.

Traditionally the left over rate was about 10% with relatively minor amount of commitment but there is currently close to 6 ETH sitting in our smart contract. We are leaning towards sending back with some admin fee/penalty (we will waive fee/penalty for those who had issue withdrawing due to technical issues).

For the time being, we extended our cooling period till 2nd June so if you forgot to withdraw, (unless you are willingly donate to Kickback) please withdraw NOW.



Thanks to Jeff Lau.


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