Client SDK
Intermediate PronunciationEN/ˈklaɪənt ˌɛs diː ˈkeɪ/
A client SDK is the analytics library that runs inside the user's browser or app, collects events on the device and sends them to the collection server.
After initialization with a project token the library keeps a device identifier, attaches default properties such as page URL and device type to every event, and sends events in batches to spare the network. Its advantage is direct access to real interface interaction; its weakness is that it sits in the user's browser, where ad blockers, privacy extensions or a fast page close can drop part of the traffic. Treat a client-side number as a floor rather than a complete count, and send money-critical events from the server instead.
FAQ
Outcomes that must be exact: payment confirmation, subscription renewal, refunds. A browser can be blocked or closed, and a few percent of loss is tolerable for behavioural reporting but not for financial reporting. Send those from the server and keep the client for interface behaviour.