The LeadCoin developers have released the Gas Crusher v1.0, an open source smart contract which is free for everyone to use. It can help to save lots of money because it reduces batch transaction fees.

The developers who were designing the platform knew that they had to create a system able to support transferring loads of leads and LDC tokens to many people. So the cost of the gas fees was one of the issues that they had to solve. As it is known, it is necessary to pay a fee for each transaction made on the Ethereum blockchain, and the fee is what the miner gets. Anyone can become a miner, so if you’re a lucky one or if you have enough computing power you can get the fee. It is calculated by the gas used for making the transaction multiplied by the gas price. You see, it works as an auction. The person who sets the highest rate enters the Ethereum blockchain first.

Of course, the users can’t wait when they want to purchase leads, so the developers’ idea was to create a platform on which the users would be able to buy hot leads while paying the smallest possible fee. Also, the system should support transferring LDC tokens in real-time mode to many users. Consequently, the team has made every effort to find a way to reduce the costs for LDC token holders.

As a result, a smart contract that allows to send tokens to the huge number of users was developed, and it became possible to make the fee much lower by reducing the amount of computing power necessary for each transaction. The mechanism has been successfully tested in Ethereum’s testnet, after that it was deployed to the real Ethereum blockchain. It was already used to deliver the bounty tokens to the users of the system. The system works well!

Technical Details:

Each transaction on the blockchain requires gas. If it’s needed to transfer a simple Ethereum token between personal wallets (non-smart contract), the gas needed is 21,000. Then you have to specify your gas price. For example, if a user chooses 15 Gwei, the transaction will cost the gas needed times the cost per gas unit – 315,000 Gwei or 0.000315 Ether (~$0.15).

But this all is about a regular Ethereum transfer: when you transfer tokens, the gas amount is higher – about 50,000 gas units for transferring to a new wallet, because creating a new wallet requires new memory on the blockchain. Memory costs an additional fee.

There are 2 ways to reduce transaction costs:

1. Choose a smaller gas price

2. Reduce the amount of gas units necessary for each transfer in this or that way

If a user decides to lower gas price, e.g. 7 Gwei, when the Ethereum network is busy, it can take him or her several hours to enter a block, and the person has to wait for the transaction to enter a block before becoming able to submit a new transaction (the reason is that Ethereum does not support parallel transactions from the same wallet). The LeadCoin team had to transfer tokens to 520 bounty winners. Such an operation could have taken 4 hours * 520 transactions = almost three months. That’s too long! Obviously, if one doesn’t want to wait so long, it’s needed to increase the gas price to about 40 Gwei.

But, instead of increasing the price, the team developed a new smart contract. It allows transferring tokens to an almost unlimited number of users in one transaction. The team transferred all the tokens to the new smart contract. All the transactions were executed at once for one low gas price 7Gwei . Once the block entered the blockchain, all the transactions came together in one piece, taking only 35,000 gas units per transfer. So the team had to wait just for two hours.

In brief, the regular price would have been 50,000 gas units * 40 Gwei * 520 = 1.04 Ether, it would allow us to make 520 transactions in a couple of hours. Instead of that, the team paid: 35,000 gas units per transfer * 7 Gwei * 520 = 0.1274 Ether in one transaction. They managed to save over 85% in gas fees.