Electronic voting provides accuracy and efficiency to the electoral processes. World democracies would benefit from a secure e-voting system not only to improve voter participation and trust but also to prevent electoral fraud. However, current e-voting systems are complex and have security weaknesses. In this paper, we describe a secure e-voting system for national and local elections (S-Vote). This system satisfies the important requirements of an e-voting system through state-of-the-art technologies and secure processes. S-Vote relies on homomorphic cryptography, zero-knowledge proofs, biometrics, smartcards, open-source software, and secure computers for securely and efficiently implementing the system processes over the various stages of the electoral process, without relying on online network connections. We outline the main conclusions of the pilot implementations of S-Vote that tested the main technologies and processes used. We also explain how the used technologies and processes achieve the system requirement. In conclusion, we recommend adopting S-Vote for its security, flexibility, economic, and scalability features.