Using MEW Offline (Cold Storage)

3 min read

For increased security, you can run MyEtherWallet (MEW) on your local computer, instead of from the GitHub servers through our website. The main computer being used to generate the transactions should not be connected to the internet. You can generate a wallet completely offline and send transactions on a different computer, which must be connected to the internet, from our ‘Send Offline’ section. In this way, your sensitive information (i.e. private key, keystore file, mnemonic phrase) is kept on an offline device, and it is never transmitted off your device.

There are two ways to use MEW offline, through the use of PWA or by downloading the client.

Using MEW Offline as a Progressive Web App (PWA)

Step 1. In order to use MEW as a PWA, you’ll first need to head to our website on Google Chrome and install MEW.

Step 2. On your online computer, scroll down to the footer to find our Offline Helper tool.

Step 3. Enter the address you’re sending from and click ‘Export JSON File’.

• Keep this safe, you’ll need it momentarily on your offline computer. Export it onto a USB for easy transfer.

Step 4. On your offline computer, access your wallet as you would normally.

• It will look a bit strange, since you’re offline.

Step 5. To the left, select ‘Send Offline’.

Step 6. Scroll down and import the JSON file you received earlier. This will fill in a few details. After that, paste the address you’re sending to and the amount you’d like to send.

Step 7. Now select ‘Generate Transaction’ and download the JSON file, or copy the Signed Transaction.

• You’ll need to use the USB from before for this step as well.

Step 8. Back to your online computer, head to the Offline Helper tool again and enter the Signed Transaction section.

• Upload the JSON file here, or paste the Signed Transaction, then press ‘Continue’. Details should generate in the next section.

Step 9. Double-check all your transaction details, then click ‘Send’.

Step 10. You’re done! You’ve just sent an offline transaction.

Downloading and Running MEW Offline

Step 1. In order to set up your local MEW, start by downloading the latest release of MEW.

Step 2. Click on MyEtherWallet-vX.X.X.X.zip to download the file. Move this file to a USB stick (or another storage transfer device), and transfer it to your permanently-offline computer.

Step 3. Plug the USB into your offline computer and extract all the files into the archive of the computer. Extracting the files is important, otherwise MEW will not open correctly and will look like a bunch of nonsense. You should end up with a folder containing these files:

Step 4. To open MEW, double-click the ‘index.html’ file. This will open MEW in your browser. You will get a warning saying it is unable to connect to the network, which is normal. You’re not connected to the internet. You won’t be able to see your ETH or token balances because of this, but these are viewable in a secure, public way by using an Ethereum blockchain explorer such as etherscan.io or ethplorer.io.

Congratulations, you’re running MEW offline! Make sure to repeat this process periodically, to ensure you’re on the most up-to-date version of our interface.

Read this article for more information on how to create a wallet. Read this article if you’d like to know how to send an offline transaction.