Prompt Caching for AI Coding: The $0 Optimization That Saves 60% on Every Call

Prompt Caching for AI Coding: The $0 Optimization That Saves 60% on Every Call If you're making multiple AI coding calls against the same codebase in a session — and you're NOT using prompt caching — you're burning money for no reason. Prompt caching is supported by Anthropic, OpenAI, Google, and most providers. It's free to enable. It cuts input token costs by 60-90%. Here's exactly how to implement it across every major provider. How Prompt Caching Works (30-Second Version) Without caching: Call 1: Send 50K context + 500 token prompt → Pay for 50,500 tokens Call 2: Send 50K context + 800 token prompt → Pay for 50,800 tokens Call 3: Send 50K context + 300 token prompt → Pay for 50,300 tokens Total input tokens billed: 151,600 With caching: Call 1: Send 50K context (cached) + 500 prompt → Pay 50,500 (cache write) Call 2: Cache hit on 50K + 800 prompt → Pay 5,800 (90% discount) Call 3: Cache hit on 50K + 300 prompt → Pay 5,300 (90% discount) Total input tokens billed: 61,600 (59% saving