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13 votes
Accepted

Is it secure to read USD / ETH rate from exchanges directly without using price oracles?

TL;DR: It is not secure to read pricing information from an exchange or other protocol. Always use a decentralized oracle. You're setting yourself up to be hacked when building smart contracts. ...
Patrick Collins's user avatar
11 votes
Accepted

How can I get USDT/USDC for Polygon Mumbai Testnet?

I've gotten some assets for polygon mumbai here: https://faucet.paradigm.xyz/ Including DAI/wETH/MATIC. Should be able to trade those for USDC/USDT. From a quick search, can trade for USDT on Mumbai ...
Kyle Baker's user avatar
5 votes

Optimism L2 USDC or USDC.e

Eh, it's a bit of a mess as of right now, so whether to use USDC or USDC.e depends on your objective. Explanation: Current USDC.e is the original bridged version on Optimism that used to be called ...
Ake's user avatar
  • 1,149
5 votes

Good Ropsten USDC faucets?

Go to Compound Finance https://app.compound.finance/asset/ Change the network to Ropsten in your Metamask Click on the USDC market Click on Withdraw and then Faucet See similar answer for DAI: ...
Peteris's user avatar
  • 1,005
4 votes
Accepted

Where to find and how to get Kovan USDC testnet tokens

https://staging.aave.com/#/faucet. You just connect with your Metamask wallet on Kovan testnet and select USD Coin. You will be prompted to accept the metamask transaction and after you will receive ...
Icarus23's user avatar
  • 351
3 votes

How can I get USDT/USDC for Polygon Mumbai Testnet?

The only way I found so far is (that still works): Create a developers account on Circle (here) and get an API key Use their demo app to add balance to your account available here or use their ...
Augusto's user avatar
  • 31
3 votes

How to get TEST USDC on Avalanche FUJI Testnet

What I did was to create a mock USDC contract. Just a simple IERC20 with 6 decimals and used that for testing purposes.
momoja's user avatar
  • 239
2 votes
Accepted

Why USDC interest rates are so high compared to USD interest rates?

The borrowers on DeFi lending pools cannot lend from a bank, because of technical risk (hacks) and the nature of the business. The borrowers are mostly cryptocurrency traders. However, they can still ...
Mikko Ohtamaa's user avatar
2 votes

Good Ropsten USDC faucets?

Try Uniswap protocol. Go to the https://app.uniswap.org/#/swap (you'll need metamask or similar tool). The idea behind this is that you swap ETH for some other token. You can specify the contract ...
igobivo's user avatar
  • 143
2 votes
Accepted

How much UNI can I earn if I become a liquidity provider?

You can only addequal USD value pair to a pool, let's see 1000 USDC/2.6 ETh (Eth price 384), the daily return is about 1.8% at the moment, based on the pool size of 25m for this pool, with daily ...
Jeffrey Lee's user avatar
2 votes
Accepted

What is the sequence of events when a transaction is made on Uniswap?

The price is not locked in. The swap rate you receive will be the rate of the pair at the time that your transaction is included in a block. However, the Uniswap protocol has a "slippage" ...
Shane Fontaine's user avatar
2 votes

Is it secure to read USD / ETH rate from exchanges directly without using price oracles?

You can use the USDC/ETH rate e.g. on Uniswap v2 pools. You can calculate the token price from reserve ratio of tokens on this pools, because reserves follow simple XY liquidity model. Range based ...
Mikko Ohtamaa's user avatar
2 votes
Accepted

Approving USDC spending using proxy contract

With proxy contracts, you have the proxy contract and the implementation contract. First off you have your terminology a little mixed up. In this case, the proxy contract would be ...
Bruce's user avatar
  • 967
2 votes
Accepted

How do I withdraw/transfer USDC back into my wallet from my copied/created contract?

Someone teaching you on youtube how to make a front running bot that can make you 5 eth a day??? If it's too good to be true, it's because it isn't true. It's a scam. There is no way to get your USDC, ...
Olivier Demeaux's user avatar
1 vote

How does USDC ever lose its peg?

Because USD/USDC trade involves other matters besides collateral Withdrawal fees Transfer fees Inelastic supply and demand for USDC
Mikko Ohtamaa's user avatar
1 vote
Accepted

Handle exchanging 6 Decimal Token to 18 Decimal Token (eg. USDC to ERC20)

Since in your case, the token is of 18 decimals, suppose you want to buy 10 tokens so the amount that you would enter is 10 multiplied by 10^18 which means 10000000000000000000. Alternatively you can ...
mzaidi's user avatar
  • 1,012
1 vote
Accepted

USDC EIP-3009 Ethereum and Polygon code mismatches

Polygon USD Coin (PoS), USDC, or any of bridged Polygon tokens are not EIP-3009 compatible. They have transferWithAuthorization function, but you need to use a different EIP-712 message for signing. ...
Mikko Ohtamaa's user avatar
1 vote

USDC EIP-3009 Ethereum and Polygon code mismatches

Where do you include the TRANSFER_AUTHORIZATION_TYPEHASH in the ethers side of things, like for creating the signature. There's the struct, that contains the relevant data about the user interaction, ...
ZrowGz's user avatar
  • 11
1 vote

How can I get USDT/USDC for Polygon Mumbai Testnet?

Use https://www.buildbear.io/ You can fork Ethereum, Polygon, Binance, Optimism, Arbitrum, Fantom, and Avalanche chains, allowing you to test your projects on the actual Mainnet state.
Chandan's user avatar
  • 11
1 vote

Is it secure to read USD / ETH rate from exchanges directly without using price oracles?

Patrick gave a great answer on why an exchange based oracle is bad, but unfortunately LINK is pretty far from trustless. Depending on the size of your contract or what you're using it for, an AMM ...
thefett's user avatar
  • 3,910
1 vote

Where to find and how to get Kovan USDC testnet tokens

Kovan is deprecated along with Rinkeby and Ropsten. Therefore, make sure to get Goerli testETH from a reliable faucet (like https://goerlifaucet.com) b/c there's lots of scam out there. Uniswap is a ...
A. Gupta's user avatar
  • 308
1 vote

How to send USDC through geth CLI?

You need ether to pay the transaction's fee. The USDC contract uses 6 decimals so to transfer 100 USDC the amount parameter should be 100 * 1000000.
Ismael's user avatar
  • 30.5k
1 vote
Accepted

Good Ropsten USDC faucets?

A dYdX API endpoint can be used to request testnet tokens. POST v3/testnet/tokens Refer to the documentation for more details.
Jance's user avatar
  • 26
1 vote
Accepted

Best way to conver ETH to a layer 2 ETH or Wrapped ETH to convert to USDC or USDT?

I don't think there is a shortcut. If you want to convert asset A to asset B the cheapest option is usually to convert it directly. Layer 2 is not meant for trying to save gas fees on Layer 1. Layer 2 ...
Lauri Peltonen's user avatar
1 vote

Usdc bep20 from trust wallet sent to usdc erc20 on metamask

i did the same thing today. i sent USDC from trust wallet to my ETH metamask wallet and it never showed. I found the bscscan tx link in my trust wallet USDC history. i clicked that and copied the &...
andrew's user avatar
  • 11
1 vote

Tokem ERC20 eth accept payament usdt

Work in the following order. Use the USDT contract's approve function to allow the user USDT to be sent to your contract address. Write a payment function in your contract. The user calls this ...
smarteasy's user avatar
  • 306

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