Questions tagged [etherscan]

Etherscan is a search engine that allows Ethereum blockchain users to look up, confirm and validate transactions that have taken place on the blockchain.

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55 votes
5 answers
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Normal transactions VS. Internal transactions in etherscan

On etherscan: -->> accounts >> contract accounts >> selecting one contract, There are two types of transactions mentioned under No Of Transactions: Normal transactions and ...
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21 votes
1 answer
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How to find solidity code for a contract address

I need to find out the public contract code i.e. solidity code for a contract address. For eample, here it has a tab for contract code but it's in assembly and byte code only, which is not useful. ...
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18 votes
3 answers
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Etherscan: How can I verify a contract with multiple imports deployed with Truffle?

When I deploy a contract with Truffle that has an import statement, and try to verify it on etherscan, my understanding is that I need to paste in the contents of the imported file. I get an error on ...
18 votes
1 answer
11k views

Are pending transactions "dropped" and "reinstated"?

I tried a simple transfer of ether between two accounts using geth, but set quite a low gas price (2 gwei). After two hours the transaction was still showing in geth under eth.pendingTransactions - I ...
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15 votes
5 answers
7k views

How do you verify a contract on etherscan that is deployed by another contract?

How do you properly verify a contract on etherscan that is deployed by another contact? I deployed a contract that deploys other contracts onto the blockchain. The original contract is verified , ...
15 votes
4 answers
25k views

Etherscan API - Get all token balances

Is there a way with the Etherscan API you can get all the erc20 token balances for a specific address? As explained here, you can see token balances with their web UI (the token tracker dropdown). ...
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13 votes
5 answers
20k views

How do I find the exact solidity compiler version used by truffle?

I'm trying to verify a contract I have compiled and deployed onto the network using Etherscan. The contract was compiled using truffle. How do I work out exactly which version of the solidity compiler ...
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12 votes
2 answers
8k views

How does Etherscan work?

From what I understand, blockchains are not optimised for searching for past transactions. Does Etherscan download the data into another database for more performant querying? If so, how can it ...
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11 votes
6 answers
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Flatten Truffle Solidity Contracts for Etherscan's `Verify Contract Code` Feature

Etherscan.io has a Verify Contract Code feature that takes the inputs Solidity Contract Code and Constructor Arguments ABI-encoded. Question: Is there a tool to flatten your solidity contracts (...
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11 votes
3 answers
12k views

How to get an ERC20 token listed in etherscan.io

In etherscan.io, under the TOKEN drop down menu, there is a list of tokens, and it is indicated that they all are ERC20 standard tokens 1) How do they get listed? Do we have to register a new ERC20 ...
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10 votes
3 answers
18k views

How to verify token after etherscan, and submit icon

Sorry, my English is not good, I verified my token on etherscan, but I do not know how to change the token's icon.
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10 votes
2 answers
804 views

How to get a contract verified on etherscan?

I'm having a hard time getting a contract verified on Etherscan. I deployed the contract using Ethereum Wallet, I can effectively find it on Etherscan but when I copy-paste the exact same code to the ...
9 votes
3 answers
4k views

Can't verify contract on etherscan.io

guys. I have created simple contract, migrated to testnet via truffle. It can be founded here. But I can't verify it. I double check: 1. name of contract 2. version of compiler (ver. 0.4.11 in ...
8 votes
1 answer
21k views

How do fronrunning and sniper bots work?

If you ever traded in defi, you probably have seen coins getting sniped at the very second of their launch and drastically inflating the prices. I assume these bots are written in js, ad using web3 ...
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8 votes
2 answers
3k views

Difference between uncle block and forked blocks

For example https://etherscan.io/uncles and https://etherscan.io/blocks_forked, what difference between them?
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8 votes
2 answers
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Best way to see a real-time list of pending transactions that have not yet been mined

I've spent all day trying to figure this out, to no avail. I'm trying to find a way to analyze the ongoing pending transactions at certain times in the day/week, to ascertain ideal times for ...
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7 votes
2 answers
4k views

Etherscan API Invalid API key

I created an account on etherscan, navigate to the API Keys settings in the user panel, and added a key. I go to the API documentation, take any API call, insert my API key, and I get an invalid API ...
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7 votes
2 answers
16k views

How to get details for an Ethereum transaction

I am using EtherScan API for finding Ethererum Stats however I see no option to find details for a particular transaction. How can I do the same?
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7 votes
1 answer
10k views

Obtain token transfer data from an address

I would like to obtain token transfer data from an address via Rest API For example, take this address: https://etherscan.io/address/0xfbb1b73c4f0bda4f67dca266ce6ef42f520fbb98#tokentxns (Etherscan ...
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7 votes
4 answers
7k views

How does etherscan fetch the number of token holders from a smart contract?

I was wondering How does etherscan fetch the number of token holders from a smart contract?
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7 votes
3 answers
3k views

Having trouble verifying a contract on etherscan.io

I'm trying to verify a contract on etherscan.io. The contract itself has a number of imports and libraries and has been deployed using certain constructor arguments. I've copy/pasted the code from ...
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7 votes
2 answers
2k views

Possible to change Etherscan verified source after initially verified? [closed]

Is it possible to change the comments in verified contract source on Etherscan once the contract source has already been verified? It isn't the Solidity source itself that I'd like to change. Just a ...
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7 votes
3 answers
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Cannot verify contract with multiple arguments at etherscan.io

When I enter all the information about a contract, the system displays the error: Error! Invalid constructor arguments provided. Please verify that they are in ABI-encoded format I fill in the ...
7 votes
1 answer
2k views

When do transactions on an exchange appear on etherscan?

Hopefully my question is self-explanatory. For example, I purchased some ether on Poloniex today. Within what time frame is that transaction likely to appear on etherscan?
7 votes
2 answers
3k views

How do I determine the constructor ABI for Etherscan contract verification?

I am facing issues trying to verify a contract that I deployed on Rinkeby. My contract constructor has 3 parameters, how do I pass values of these parameters in the contract verification form? How ...
7 votes
3 answers
18k views

Error! Unable to generate Contract ByteCode and ABI

Having issues verifying my token contract on etherscan.io. Receiving the following errors: Note: Contract was created during Txn# Result: Does not match the input creation bytecode found at this ...
6 votes
2 answers
6k views

How do I get the implementation contract address from the proxy contract address?

I'm using web3.py to interact with multiple unknown contracts, where I don't know beforehand if a contract is a proxy contract or the actual contract. I'm getting the ABIs for the contracts on-the-fly ...
6 votes
2 answers
3k views

weird transaction sending to self

see some weird txs calling self addresses, for example, the last 2(the first and second tx in this block) transactions, at https://etherscan.io/txs?block=6475251&p=2 https://etherscan.io/tx/...
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6 votes
3 answers
4k views

How do I determine whether the transaction is used for the contract creation?

I want to monitor Ethereum and memorise every contract published on the blockchain (basically the same thing that Etherscan does). How it is possible to do this using NodeJS & web3? How can I ...
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6 votes
1 answer
4k views

I got "sandwich attacked" on my transaction

I see a new kind of arbitrage bot today. As per my research we call that "sandwich attack" ... Here how the user proceed : I buy for 7.8ETH of a token, and it look like a bot is buying ...
6 votes
1 answer
2k views

My friend sent me a screenshot of a transaction hash, but when I search for it I find divergent data. What happened?

This is the transaction hash: 0x90e923ee01d9dfeb95ee176819eeec67d247fc6cb009c8cdc4d8ae1939e5ecc6 And this is the screenshot my friend sent me: If you check the hash in Etherscan, some informations ...
  • 61
6 votes
5 answers
14k views

API for ERC20 token balance - EtherScan

Is there any API for ERC20 token balance of an address for a particular contract?
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6 votes
2 answers
4k views

Failed transactions on Etherscan

while looking on Etherscan I see a several types of failed transactions: Bad Instruction Bad Jump Destination Reverted Out Of Gas I can only understand Out Of Gas failure. what is the reason for the ...
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6 votes
1 answer
6k views

Unable to verify Solidity contract code on etherscan.io

I know this question has been asked many times before. I've read loads of answers, but nothing seems to work for me. I first tried to verify the source code of a much larger, more complex contract, ...
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6 votes
1 answer
2k views

Jaxx Wallet QR Code shows IBAN and etherscan shows 0 balance

When I scan the QR code from the Jaxx Etherium wallet I get iban:XE482ECP16CJCBQHZ7S844BEK8K1SDOX0HH but it shows my address as 0x1488e397bc44c56d801a6e96217554a0e310ecb5 in the app it shows I ...
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6 votes
1 answer
439 views

Is it possible to transfer ERC20 tokens without sending a transaction to the contract address?

I'm trying to reverse engineer etherscan so I can make my own explorer. While I was checking Augur token transfers I found a transaction where both the to and from address where different from the ...
6 votes
3 answers
908 views

Inability to verify contract with ABIEncoderV2 on Etherscan

Yesterday I deployed a contract to Ropsten (https://ropsten.etherscan.io/address/0x1fe59c223fa4e9781237f0f49a15ca598069cc30) that relies on V2 of the ABI encoder. Thus it includes statement pragma ...
6 votes
1 answer
3k views

Etherscan: Effectively paginate `Event Logs` result

I am using Etherscan API for various Ethereum details. I need to find out the tokens transferred from a token original contract (let's say A) address to a particular address(let's say B). For this ...
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6 votes
1 answer
2k views

API resource for determining all address holders of a contract

I would like a RESTful API for viewing all addresses which holds a balance of a specific contract. It seems that etherscan.io deprecated this feature, or I'm looking at the wrong endpoints Are there ...
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5 votes
3 answers
6k views

How do I get the latest block using etherscan api?

I'm trying to get the latest block (it's height) using Ethereum Developer APIs of etherscan. For example, I can get it from blockcypher using the following URL: https://api.blockcypher.com/v1/eth/...
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5 votes
2 answers
3k views

How does EtherScan know I am sending to a Shapeshift/Poloniex wallet?

I have noticed many transactions on Etherscan that indicate one of the parties is a certain type of wallet (e.g. Poloniex or Shapeshift). Here is an example. How does it identify the source? Do these ...
5 votes
1 answer
42k views

How to manually approve a token for swap on Uniswap (direct contract interaction)

I want to approve token spending on Uniswap for a token I don't own. Uniswap UI won't let me do that (instead it displays a gray out button "insufficient balance"). Seems the only option ...
5 votes
1 answer
2k views

What's the meaning of "similar match" in source verification? [closed]

I'm looking at a contract that shows an orange badge and reads Contract Source Code Verified (Similar Match), providing a different address (with the same code). Does anybody know what this means? (I ...
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5 votes
4 answers
2k views

I can't verify my contract on the Rinkeby etherscan site

I'm getting the following error when verifying on the RINKEBY etherscan site: Error! Unable to verify source code Exception #1 Occured: ERROR|The Contract solidity compilation has exceeded the ...
  • 795
5 votes
2 answers
4k views

Etherscan api for Ropsten testnet

I found this endpoint is to obtain the token balance from Ethereum blockchain, however, I noticed that this function doesn't work on Rospten network. Please advise https://api.etherscan.io/api?module=...
  • 173
5 votes
1 answer
2k views

How to know which ERC20 tokens a wallet owns?

On Etherscan, when you view the details for a particular address, you can see a list of ERC20 tokens which are owned by that address: How does Etherscan do this? It is my understanding that you have ...
  • 397
5 votes
1 answer
6k views

How can I verify ownership to allow resale of NFTs?

I have discovered NFTs and ETH recently and would like to build a marketplace like opensea but allows resale of NFTs that are already minted on various block chains(ETH, FLOW). Starting with just ETH, ...
5 votes
2 answers
1k views

Cannot verify contracts with libraries on Etherscan

Since the last week I have not been able to verify contracts on Etherscan if they use libraries. I was able to do this before. Apparently something has changed in Etherscan, Solidity compiler, or ...
5 votes
3 answers
4k views

What process does Opensea use to get all the NFTs of a wallet?

I'm new to this so excuse my n00bness. I created an NFT through Remix on Rinkeby and then log into Opensea and the NFT appears nicely in my account. But how are Opensea finding that data? Are they ...
5 votes
1 answer
1k views

what's the "Contract Creation Code" in Etherscan Verfied Contract?

what's the difference between "Contract Creation Code" in Etherscan Verfied Contract and the bytecode compiled by Solc?

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