Reducing OpenAI API costs for existing integrations without degrading quality, typically achieving 30-60% cost reduction through a combination of model routing, caching, and prompt engineering. Model routing by task complexity: GPT-4o mini at approximately $0.15/1M input tokens for high-volume, focused tasks (classification, extraction, short-form generation) that don't need GPT-4o's reasoning depth; GPT-4o reserved for complex multi-step reasoning tasks where the quality gap is measurable. Semantic response caching with a vector similarity threshold: queries with cosine similarity above 0.95 against a cached query return the cached response rather than triggering a new API call, effective for FAQ-style integrations where users ask the same questions with minor wording variations. OpenAI Prompt Caching for long system prompts that appear in every request, repeated prompt prefix segments cached at the OpenAI side reduce both latency and cost. Prompt compression to reduce input token count without information loss. Output length constraints via max_tokens per task type. Production monitoring via LangSmith or a custom logging layer: cost per conversation, median and p95 latency, error rate by error type, and token usage by model, so cost anomalies are visible in real time, not discovered at month-end billing.