MoneroBolt
Build your own Monero node on a personal computer: monerod over Tor, desktop and mobile wallets, and P2Pool mining. No need to trust anyone else.
Read the guide /monero-seed-tool/Monero Seed Tool
Offline seed and address inspector. Generate or check 25-word seeds and Polyseeds, apply a seed offset, and derive keys and addresses. Save the page and use it on an air-gapped computer.
Open the tool