Den is an interface on top of the Safe Contracts. These contracts have been well tested and audited. You can find the audits here.
Safe is the most popular mechanism for teams to store assets on-chain and is trusted by DAOs, DeFi Protocols, Investment Firms, and other security conscious organizations. Over $39B is stored in Safe contracts, representing about 5% of all cryptocurrencies.
Due to the security mechanisms implemented in the Safe contracts, Den is not able to modify the Safe Contracts or any transactions that a user has signed or executed.
Den’s interface and bot software are well-tested and subject to stringent review before deployment. Address labels and transaction description messages are only visible to other owners of the Safe, who’ve proven their ownership by producing a verifiable EIP-4361 compliant cryptographic hash. That data is stored on servers managed by the Den team, which is inaccessible to all but permissioned Den engineering team members that have been 2 factor authenticated, so that information stays private.