Three things that are often confused
| Item | What it is | Who may see it | What it allows |
|---|---|---|---|
| Public address | A string such as bc1q… or 3… derived from a public key | Anyone. You share it to receive Bitcoin. | Receiving Bitcoin; looking up balance and history |
| Private key | A secret number that signs transactions for one address or many | Only you, ever | Spending the Bitcoin at the corresponding addresses |
| Seed phrase | 12 or 24 words from which all private keys of a wallet are regenerated | Only you, offline | Recreating the whole wallet and spending everything in it |
The blockchain contains public addresses and transactions. It never contains private keys or seed phrases. That is why looking up an address is safe and why spending needs something the blockchain does not have.
What can be seen with only a public address
- The current balance of the address.
- Every transaction that sent Bitcoin to it or spent from it, with amounts, timestamps, block heights and confirmations.
- The other addresses involved in those transactions.
- The fee each spending transaction paid.
This is exactly the information a block explorer shows, and exactly what BTC Mate uses.
What cannot be seen or done with only a public address
- Spending. A transaction is only valid with a signature from the private key. An address alone cannot produce one.
- Identity. The blockchain does not record names. Linking an address to a person requires outside information.
- Purchase price. Prices and currencies are not on-chain. Any profit figure is an estimate built from market history. How BTC Mate estimates it.
- Other addresses of the same wallet. Modern wallets use many addresses. A single address does not reveal its siblings unless they appear together in a transaction.
Can someone steal Bitcoin with a public address?
No. Public addresses are meant to be public; every payment you have ever received was made to one. Sharing a public address does not give someone control over the funds, but it does reveal the balance and transaction history of that address and therefore has privacy implications. Keep private keys and seed phrases offline and never type them into a phone, a website or an app that merely displays information.
Why BTC Mate only needs the public part
BTC Mate is an iPhone app for tracking and analyzing public Bitcoin addresses. Its features, balance, activity, estimated performance, address lookup and blockchain insights, are all derived from public data. There is nothing in the app that could use a private key even if it had one: no transaction builder, no signing, no sending, no trading. The app has no field for a private key or seed phrase, and the developer never asks for one.
Your public addresses are stored on your device. To fetch their history the app sends the address to a blockchain data provider, which is described in the Privacy Policy.
Rules of thumb
- Public address: fine to enter in a tracker, an explorer or an invoice.
- Private key or seed phrase: only ever into the wallet that is supposed to hold it, ideally a hardware device, and never to "verify", "track", "sync" or "claim" anything.
- If a tracking app asks for your seed phrase, it is not a tracking app.