BitTool Signer

BitTool Signer turns a spare iPhone into an offline signing device. Your keys are created and kept on that phone, every request is decoded before you sign, and signatures leave only as QR codes. AIR-GAPPED BY DESIGN • No networking code: the app cannot send or receive anything, even if iOS allowed it • No accounts, no servers, no cloud sync, no analytics • Built to run in Airplane Mode on a dedicated iPhone, with a built-in setup guide • Encrypted wallet files are excluded from iCloud and computer backups SEE EXACTLY WHAT YOU SIGN • Every request is decoded on the device: amounts, recipients, contracts, fees and the exact bytes • Each request is matched to the wallet that should sign it, with a fingerprint you can compare • Plain-language warnings for unlimited approvals, unknown tokens, message signatures and other red flags • NFT transfers, approvals and marketplace listings show what you give, what you get and who else receives • No blind-signing switch: anything that cannot be fully decoded needs your explicit consent, every time A PASSWORD FOR EVERY SIGNATURE • Each wallet is encrypted with your password (PBKDF2, 600,000 rounds, and AES-256-GCM), plus a second layer with a key that never leaves this iPhone • No global unlock and no remembered sessions: every signature needs that wallet's own password • Optional Face ID app lock • Wallet content is hidden in the app switcher and while the screen is being recorded BACKUP DONE RIGHT • Your recovery phrase stays concealed until you tap, and hides again when you leave the screen • A backup check makes sure every word is written down, in order • Recovery cards split your phrase across three cards; any two restore the wallet • Import phrases in all 10 BIP39 languages, with checksum validation and optional passphrase support WORKS WITH THE WALLETS YOU USE • Pair once with BitTool Wallet: one QR code sets up Bitcoin, EVM networks, TRON and Solana as a watch-only wallet • Open standards (BC-UR, PSBT and EIP-4527) work with many popular Bitcoin, EVM and Solana wallets • Bitcoin: Native SegWit, Taproot, Nested SegWit, Legacy, and multisig cosigner keys • Ethereum, BNB Chain, Arbitrum and Base: transactions, personal messages and EIP-712 typed data • TRON and Solana: transactions and messages • 3,350 tokens recognised offline across 10 networks FULLY OPEN SOURCE The app, the offline signing engine and the token data are published on GitHub. Read exactly what BitTool Signer does with a recovery phrase, then rebuild it and compare with the copy you installed. HOW IT WORKS 1. Create or import a wallet on your offline iPhone and write down the recovery phrase. 2. Show the pairing QR code to a watch-only wallet such as BitTool Wallet. 3. When you send, scan the unsigned request with BitTool Signer, review it and enter the wallet password. 4. Scan the signature QR code back into your wallet, which broadcasts the transaction. GOOD TO KNOW BitTool Signer is self-custody software. Nobody, including us, can recover a lost recovery phrase, reset a wallet password or reverse a signed transaction. BitTool Signer never broadcasts transactions; your watch-only wallet does. Privacy: BitTool Signer collects no data. Website: https://bittool.com/signer Support: [email protected]