[Home](./index.md) > [@snowplow/node-tracker](./node-tracker.md) > [TrackerCore](./node-tracker.trackercore.md) > [addPayloadPair](./node-tracker.trackercore.addpayloadpair.md) ## TrackerCore.addPayloadPair property Set a persistent key-value pair to be added to every payload Signature: ```typescript addPayloadPair: (key: string, value: unknown) => void; ```