What Is a Self-Custody Bitcoin Wallet?
Your Bitcoin is controlled by a private key — a long string of characters that proves ownership on the network. Whoever holds the key controls the Bitcoin. There is no second layer of security underneath that.
In a self-custody wallet, the key lives on your device. The company that built the wallet never sees it. If the company gets bought, sued, or shuts down on a Tuesday, your Bitcoin is still there. You hold the only thing the network respects: the key.
Most people who own Bitcoin do not have this. They have an account on an exchange, which is closer to an IOU than to actual Bitcoin. The exchange holds the keys. You hold a login.
What an exchange actually holds
When you buy Bitcoin on Coinbase or Binance, the exchange creates a balance entry in its database. Your Bitcoin sits in the exchange's wallets, mixed with everyone else's. You can see the number in your account, but you cannot point to specific sats on the blockchain and say "those are mine."
You are trusting the exchange to keep track, stay solvent, and let you withdraw when you ask. This is the same arrangement as a bank, with one important difference: there is no government insurance behind a crypto exchange. If it goes under, you are an unsecured creditor standing in line behind everyone else the exchange owes money to.
FTX collapsed in November 2022. Customers had balances on screen the day before. The next morning, the Bitcoin was simply gone — moved out by people running the company to plug holes nobody had been told about. Mt. Gox collapsed the same way in 2014. Celsius, BlockFi, Voyager — same model, same ending, all within the last few years. These are not edge cases from early crypto. FTX was the second-largest exchange in the world the day it died.
Bitcoin was built so you would not have to trust an institution with your money. An exchange account puts you back into trusting an institution. Same risk, slightly newer building.
What self-custody changes
A self-custody wallet derives a private key on your device. That key controls specific sats on the blockchain. When you want to move them, the wallet signs a transaction with your key and broadcasts it to the network. No one approves it. No compliance review, no daily withdrawal limit, no human in the loop. The blockchain sees a valid signature, and the sats move.
The wallet app is just an interface — it shows your balance, builds the transactions, and talks to the network. The key is the thing that matters, and the key is on your phone. If the wallet company disappears tomorrow, you can take that key to a different self-custody wallet and your sats are exactly where you left them.
Older wallets generate a 12 or 24 word seed phrase and ask you to write it down. You hope you do not lose the paper, and you hope nobody photographs it. Newer wallets like Piggy use a passkey instead — the same kind of key your phone already uses for Face ID. The key material is held by your device and synced through Apple or Google automatically. No paper to lose, no twelve words to memorize, same custody model underneath.
What you are responsible for
If you lose access to your key and have no backup, the Bitcoin is permanently gone. There is no customer support line, no recovery flow, no manager you can ask for. The blockchain does not know who you are, and it does not care.
This is the tradeoff. Full control, full consequences. Passkey wallets soften it by leaning on the syncing your phone already does — your phone breaks, you sign in on a new one, the passkey comes with you, the wallet re-derives the same keys. Piggy also lets you optionally export a 12-word recovery phrase as a second backup if you want both.
The honest comparison: people who use a passkey wallet with an exported backup lose Bitcoin to user error at roughly the rate they lose passwords. People who keep Bitcoin on exchanges have lost billions of dollars to other people's decisions in the last ten years. Both technically count as "ways to lose your Bitcoin," but the risks are not equivalent.
Why this matters for saving
If you are stacking sats over time and leaving them alone, self-custody is the setup where you actually own what you are saving. An exchange balance is a claim against someone else's company. A self-custody wallet is your key, your sats, on the blockchain, with no third party who can change the rules.
Piggy is built specifically for this. Your keys are derived on your phone from a passkey. We never see them, we never store them, and we could not access your sats even if we were ordered to by a court. Feed your Piggy sats, leave them alone, and they stay yours.