I have an error from web3:

Unhandled rejection Error: Given address "0x" is not a valid Ethereum address.

My question is if is there any tool that can fix my address (add checksum).

  • Looks like you're trying to pass an illegal address, without any trailing zeros. Are you trying to send to the zero address (0x0) ? – jojeyh Oct 15 '17 at 21:21
  • No I found out that etherscan.io is formatting address in correct form with checksum, but I still have warning from web3. – gkucmierz Oct 15 '17 at 21:25
  • Here is an online tool for you tokenmarket.net/ethereum-address-validator – Mikko Ohtamaa Mar 15 '18 at 8:45

If you prefer a simple web version, check out EthSum. Disclaimer: I'm the author, it's an open source tool.


With web3 you can do:

web3.toChecksumAddress('INSERT ADDRESS HERE')

It will return the address with checksum


Yes, you can.

Replcae your address in the following url of etherscan https://etherscan.io/address/{address} like this:

you want the checksum for address 0x0fd60495d705f4fb86e1b36be396757689fbe8b3 so you need to call https://etherscan.io/address/0x0fd60495d705f4fb86e1b36be396757689fbe8b3 then copy the address with valid checksum 0x0Fd60495d705F4Fb86e1b36Be396757689FbE8B3 on the loaded page.

enter image description here


These are the functions you're looking for: specification of the corresponding EIP and the implementation.

  • Is there an interactive online version anywhere? – Stan James Oct 17 '17 at 22:38

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