Non-custodial describes a wallet or service model where users keep control of their own private keys instead of giving them to a provider. In this setup, the provider can help with software, interfaces, or network access, but it cannot directly move funds without the user’s authorization. That makes key theft and insider abuse less likely than in custodial systems, where the operator holds the assets or the signing keys.
In cyber security, non-custodial design is important because it changes the trust boundary. Attackers may still target the wallet app, browser extension, bridge contract, or transaction-signing flow to trick users into approving a malicious action. Defenders use clear signing prompts, hardware wallets, contract verification, and limited permissions to reduce that risk. Non-custodial does not mean risk-free: if bridge software, smart contracts, or recovery procedures are flawed, user funds can still be exposed even when the keys stay in user hands.