Making an Offline Transaction

3 min read

If you are using MyEtherWallet (MEW) offline and locally, it is not possible to send transactions directly from the offline computer. To send or broadcast a transaction, an internet connection is required. To do this, you should use a second computer that is connected to the internet. This has the advantage of keeping your private key on a separate offline device that won’t be afflicted by malware or hackers.

Find the Nonce & Transaction Details

Step 1. Head to MyEtherWallet.com on your online computer.

Step 2. At the bottom, in the footer, choose the ‘Send Offline Helper’ tool.

Step 3. Choose the network you are interacting with.

• Leave it on ‘ETH’ if you are using Ether or ERC20 tokens.

Step 4. Fill in the address you are sending from, and our interface will generate a gas price and nonce for your transaction, along with other details

Step 5. Make a note of your nonce, export the JSON file, and move this file onto a USB.

Generate Your Offline Transaction

Step 1. Plug in the USB to your offline computer.

Step 2. Access the offline version of MEW on this same offline device.

• This is done by opening ‘Index’ from the file list with your browser.
• If you do not have MEW downloaded for offline use, this article will help you download the MEW web interface.

Step 3. Access your wallet like you would normally, and choose ‘Send Offline’ from the menu to the left.

• It’s important to use the ‘Send Offline’ tab instead of the regular Transaction tab, because the ‘Send Offline’ interface allows you to select any token for sending.
• In order to see the tokens in the ‘Type’ dropdown, you may need to refresh the token list to the right. Keep in mind that you will not see a connection, since you’re not connected to the internet, but this will refresh the token information so that it appears in the dropdown.

Step 4. Import your JSON file from the connected USB.

• Alternatively, you can manually fill in your nonce, transaction details, and the address you are sending to, as well as other relevant data.

Step 5. If you’re sending to a contract, extra data may cause you to need a higher gas limit.

• Excess gas will be refunded, so don’t be afraid to raise it as high as 100,000.

Step 6. Click ‘Generate Transaction’, then copy the long string that says ‘Signed Transaction’ and paste it in a text file, or download a new JSON file holding your signed transaction’s details. Drag this text file or JSON file into your USB for the final step in the process.

Sign and Send Your Transaction

Step 1. Head to MyEtherWallet.com once more on your online computer.

Step 2. At the bottom, in the footer, choose again the ‘Send Offline Helper’ tool.

Step 3. Paste in your signed transaction, or import the new JSON file you just received, then press ‘Continue’.

Step 4. Review the details of your transaction then press ‘Send’.

You’re done! Your transaction will show on an Ethereum blockchain explorer once it’s been verified. It can be searched using the transaction hash shown at the end of the process.