3) and my server will relay that transaction to a Smart Contract on the Ethereum network. I want to encrypt / sign these transactions on the client side (the mobile app) and then decrypt it on the Smart Contract side using a private / public key, so my plan is to hardcode the private key into the mobile app. If you know the private key then you own all bitcoins and ethereums in it. Blockchain hackers are using such methods and they have stolen more than 50$ million in ethereum. What is a private key? A private key in the context of Bitcoin or Ethereum is a secret number that allows the crypto-coins to be spent.

Yes, your private key is on this website too, but don't worry, nobody will ever find it.
If you want to try searching for your wallet, click one of the buttons below.

How does this work?

A private key is basically just a number between 1 and 2²⁵⁶. This website generates keys for all of those numbers, spread out over pages of 128 keys each.
This website doesn't actually have a database of all private keys, that would take an impossible amount of disk space. Instead, keys are procedurally generated on the fly when a page is opened. The page number is used to calculate which keys should be on that page.
Finding an active wallet is hard, but not impossible. Every time you open a random page, you have a chance of finding someone else's fortune.
If you're curious which page your wallet is on, you could do a search for it. That will show you exactly which page your wallet is on.

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Automatic balance checking

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The balance of each wallet is automatically checked. Wallets with a balance are colored green. Wallets that have been used in the past but are now empty will turn yellow. Wallets that have never been used are red.