The best free alternative to ThingSpeak is Beebotte. If that doesn't suit you, our users have ranked more than 10 alternatives to ThingSpeak and 16 is free so hopefully you can find a suitable replacement. Other interesting free alternatives to ThingSpeak are Android Things (Free), The IoT Guru (Freemium), DataGekko (Freemium) and Ubidots (Freemium).
This platform is aimed at enthusiasts who have a basic knowledge of Internet of Thing (IoT) devices. M2mlight.com is a free basic platform service for IoT devices. You can store your cameras, sensors, actuators and alerts data in the cloud.
One main focus is customizability without making the configuration too complicated. While Palamoa expects data in JSON format, its content is fully configurable. Any sensor device that can send JSON data can easily get connected.
thethings.iO makes a real-time IoT cloud solution that supports REST, MQTT, CoAP and Websockets. It has a free account up to 3 devices, and then charges 1 Euro per thing per year for realtime storage, analytics, and interoperability features.