# Tip-Center:Tips on chain

By [Cryptowan](https://paragraph.com/@cryptowan) · 2021-11-21

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Tip-Center
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Because the blockchain (especailly Ethereum) currently has too high gas fees, it is too expensive to make multiple small transfers on chain. For tipping (especially a small tip), use the blockchain It is not an optimal solution due to high gas, but web3 is originally an Internet with frictionless circulation of value, and that is what tipping need. Therefore, for tipping, it is more suitable for a decentralized form than a centralized system. Tip-Center is a semi-offline reward/sociafi system, users can send small rewards without interacting with the blockchain, and finally settlement on chain. The system combines functions such as tipping, over-collateralization, and mortgage mining.

Design
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1.  Because the gas cost of each reward transfer on the chain is too high, so we pledged on chain, send checks off the chain, and then merge and wash batch check(we use check form to transfer a tip) on chain together.
    
2.  If someone uses a check to write a bad check (the total amount of checks written is greater than the pledged amount or opens an unpledged check), there will be no enough token on chain to cash out, so punishment is required. In the real world, the law is used to enforce fines, but the chain there are no compulsory measures, so excess pledged are required.
    
3.  If we use excess pledged, the excess part(we called staking) will be locked, resulting in lower capital utilization efficiency (because the excess pledged part will have no investment attributes), so the defi mining mechanism is introduced to compensate the entire pledge pool by penalizing others for the bad performance , and in future versions, the excess funds wil also be transfered to makerdao or other defi system to further improve the efficiency of funds.
    

work process
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1.  The user calls `add_tipBook()` to add his own tipbook and obtain the id, and then pay the tip by signing the nonce, id, and beneficiary.
    
2.  After receiving multiple tips, the tipped person can call `cash_out()` to cash out tips.
    
3.  After the user consumes the tip book, he calls `refund()` to apply for withdrawal and receive staking mining rewards.

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*Originally published on [Cryptowan](https://paragraph.com/@cryptowan/tip-center-tips-on-chain)*