Electrum

Electrum starts with a lighter local setup than a full Bitcoin node. Its servers supply transaction history and relay transactions, while the client checks confirmed transactions using payment proofs. That saves resources but has a privacy cost: a server can infer which queried addresses belong together, and it supplies information about unconfirmed activity.

Keep signing offline

For an offline wallet, the desktop guide separates the private signing wallet from an online watching-only copy:

1. On the offline computer, create the wallet and obtain its Master Public Key from Wallet > Information.
2. On the online computer, use File > New/Restore, choose Standard wallet and Use public or private keys, then supply that public key.
3. Prepare the payment in the watching-only wallet and save the unsigned transaction from Preview.
4. Load that file on the offline wallet through Tools > Load transaction > From file, sign it, and return the signed file to the online wallet for broadcast.

The watching-only copy can show history and prepare a payment; it cannot sign one by itself. Keep the private recovery material on the signing side.

Recovery and fees

A forgotten Electrum password cannot be retrieved. With the saved seed, you can restore a wallet and choose a new password. Imported private-key wallets are a different case and need their own backup because a seed does not recover separately imported keys.

The software is free under the MIT license. Bitcoin network fees still apply, and confirmation timing depends on network conditions and the transaction's fee. Electrum provides dynamic estimates and fee-adjustment tools for eligible transactions; those tools do not guarantee an immediate confirmation.