How much does it cost to build an LLM gateway that routes, caches, and meters?
An LLM API gateway sits between your clients and LLM providers, handling routing, caching, token metering, rate limiting, and auth. It's a common pattern for companies that want to control LLM access across teams or products. Here's the build cost.
| Infrastructure Item | DIY Time | DIY Cost | With Kit |
|---|---|---|---|
| FastAPI project + async infrastructure | 4–6 hours | $400–$900 | Included |
| Multi-provider LLM abstraction layer | 12–20 hours | $1,200–$3,000 | Included |
| Provider routing + fallback logic | 8–14 hours | $800–$2,100 | Included |
| Response caching (Redis) | 6–10 hours | $600–$1,500 | Included |
| Token counting + usage metering | 8–12 hours | $800–$1,800 | Included |
| API key auth + per-key rate limiting | 8–12 hours | $800–$1,800 | Included |
| SSE streaming passthrough | 6–10 hours | $600–$1,500 | Included |
| Stripe usage billing integration | 10–16 hours | $1,000–$2,400 | Included |
| Logging, monitoring + deployment | 6–10 hours | $600–$1,500 | Included |
| Total | 68–110 hours | $6,800–$16,500 | $69 one-time |
The bottom line
An LLM gateway is mostly infrastructure — routing, metering, caching, auth. FastAPI AI Kit provides the entire infrastructure layer, so you can focus on the routing rules and policies specific to your organization instead of building plumbing.
Skip the infrastructure cost
FastAPI AI Kit includes every item in the table above — auth, LLM integration, RAG, billing, and deployment — for a one-time purchase that costs less than 30 minutes of senior developer time.
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