I'm interested in the Metamask App (Android) and I'm wondering how exactly the sending of funds works: Since the 12 words (and the corresponding private key) are generated on my mobile device (correct?), what happens when I send funds to another address?

Is my private key sent (but hopefully not stored) to some server that handles the transaction? My understanding is, that my phone cannot do transactions on its own, since it doesn't have the whole ~300 GiB blockchain accessible?

This question is specific to Metamask and the Ethereum blockchain, but I guess the same question could be asked for Bitcoin (and some mobile wallet) or another blockchain.

Thank you for your help!

  • 1
    This is a very product specific question and requires deeper knowledge of the product. It is probably better asked at a site more specific to the problem domain, i.e. like Ethereum.
    – Steffen Ullrich
    Aug 8, 2021 at 11:47
  • Thank you for the clarification. Do I delete this question here then?
    – Lupos
    Aug 8, 2021 at 11:58

1 Answer 1


MetaMask is a non-custodial wallet that doesn't store your private key in its server.

Here is an excerpt from their website.

We cannot access your wallet from our side, you are the only person who can access it directly from the browser/mobile app.

Your transaction is signed locally with your private key and the key is never shared with a remote server. The signed transaction is perhaps sent to MetaMask's server first and then they broadcast it to the Ethereum network with their node or the third party like Infura.

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