Example implementations relate to secure messages for IoT devices. For example, a system for secure messages for IoT devices may include an IoT device coupled to a network including a plurality of web services. The IoT device may store a service certificate for each of the plurality of web services, generate a secure message for a web service among the plurality of web services using the stored service certificate for the web service, and send the secure message to the web service without first establishing a connection between the IoT device and the web service.