CertiK is a formal verification framework to mathematically prove that smart contracts and blockchain ecosystems are bug-free and hacker-resistant. To scale the verification, CertiK developed a layer-based approach to decompose such an otherwise prohibitive proof task into smaller ones. These smaller proof obligations can be encoded in the CertiK transactions and will then be proved and validated by the participants in a decentralized style. CertiK ledgers work as certificates to exhibit the end-to-end correctness and security of verified smart contracts and verified blockchain ecosystems, making them entirely trustworthy.