Node-RED is a free, JavaScript-based server and web GUI for wiring together hardware devices, APIs and online services. You can find a lot of example flows and additional nodes in the Node-RED Library.
With the Node-RED node for TTN it is very easy to process device messages and activations with pretty much no code.
⚠️ The support and maintenance for this SDK has been discontinued, it is not recommended to use the SDK for new projects.