Stop sending your entire RAG context every time. The math behind Anthropic's 90% Caching discount.

Hey Indie Hackers,

A month ago I posted here about the "Retry Tax" that drains SaaS API budgets. Today I want to talk about the opposite: the single biggest cost-saver in 2026 SaaS architectures.

If you are building AI wrappers, RAG apps, or coding assistants, you are probably sending the same huge system prompts, documents, or codebases to Claude 3.5 or DeepSeek thousands of times a day. You are paying full price for data the model has already processed.

Both Anthropic and DeepSeek recently introduced "Prompt Caching," offering up to a 90% discount on input tokens if the context was cached within the last 5-60 minutes.

The problem? Most founders don't know how to calculate if the architecture change is worth the engineering effort. It depends heavily on your "Cache Miss Rate" (how consistent your user traffic is).

To visually solve this, I added a new tool to my hub: the Prompt Caching Cost Optimizer.

You can plug in your Static Context Size (e.g., your 50k token RAG doc), your Monthly Queries, and your assumed Cache Miss Rate, and it instantly calculates your exact monthly savings vs standard API pricing.

It's entirely free and runs client-side. Check the math for your SaaS here: https://bytecalculators.com/prompt-caching-optimizer

For those running high-traffic AI tools here: Have you switched to a caching architecture yet? Does the 5-minute cache lifespan on Anthropic actually match your user session lengths?