GTL (Guide Template Language) is used in Marketing Cloud's Content Builder to process JSON responses directly inside email content. Since Sunny Sky API provides weather information likely in a JSON format, GTL is the appropriate way to parse the response and personalize the email in real time without needing external services or complex scripting.

—

Exact Extract from Salesforce Documentation:

Source: Salesforce Help – Guide Template Language (GTL)

→ "Guide Template Language (GTL) enables parsing of JSON objects for dynamic content inside emails, CloudPages, and SMS messages. GTL is designed specifically to personalize content using external data sources directly within a send."

Source: Marketing Cloud Developer Guide – GTL Overview

→ "Use GTL to retrieve, parse, and render JSON content into Marketing Cloud messages."

—