LLM API integration is the process of connecting applications to large language model providers through standardized interfaces, enabling developers to leverage AI capabilities without managing infrastructure. Modern LLM APIs offer unified formats across providers (OpenAI-compatible endpoints), sophisticated streaming and function calling, and built-in cost optimization through caching and batch processing. The key challenge lies not in calling a single API, but in building resilient, observable, and cost-effective systems that handle rate limits, fallbacks, context management, and multi-provider routing—skills that separate prototype AI apps from production-grade deployments.

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