The deployment of quantum technologies will be reliant on developing platforms that are mass-manufacturable and cost-effective. Quantum key distribution is a protocol that ensures secure communications between various parties within a network using shared secret keys to encrypt the communication channels. However, practical implementations with hybrid systems can leave side channels open, which compromises the security of the network. Semenenko et al. demonstrate a quantum-ready platform based on all the optical components being monolithically integrated on an indium-phosphide photonic chip. With the side channels to information leakage effectively closed and demonstrated secret keys exchanged at rates exceeding 1 kilobit per second over 100 kilometers, such a platform provides a promising solution for the development of secure communication over citywide quantum networks.