Choosing the Right LLM Routing Strategy: Lowest Cost, Balanced, Fastest

Once you're routing LLM traffic through one API, the next question is: which strategy do I use for which workload? Picking the right one keeps cost down and quality where it matters.

Lowest cost

Use when: High volume, non-critical tasks—e.g. internal tooling, drafts, summarization, or background jobs where a slightly weaker answer is acceptable.

The router prefers cheaper models (e.g. GPT-4o-mini, Claude Haiku, Gemini Flash) and only steps up when needed. Combine with a per-request cost cap so no single call blows the budget. Best for: "I want the cheapest acceptable answer."

Balanced

Use when: General production traffic where you care about both cost and quality—e.g. customer-facing chat, support, or mixed workloads.

The router weighs cost, quality, and latency. You get a sensible default without tuning. Good when you don't want to think about it per request. Best for: "Good answers at reasonable cost and speed."

Fastest

Use when: Latency matters more than cost—e.g. real-time UX, inline suggestions, or strict SLAs.

The router prefers low-latency models and regions. Use when every millisecond counts and you're okay paying a bit more. Best for: "I need the quickest response."

Max reliability

Use when: Critical paths—billing, compliance, or high-stakes decisions where you want the most reliable model and provider.

The router favors models and providers with strong uptime and consistency. Best for: "I can't afford flakiness or downgrades."

Mixing strategies

You don't have to pick one for the whole app. Route by use case:

• Lowest cost for internal or batch work.
• Balanced for most user-facing features.
• Fastest for real-time features.
• Max reliability for payments, legal, or safety.

Some routing layers let you pass the strategy per request (e.g. in the body or header), so the same endpoint can serve all of the above. Add a cost cap so even "max reliability" never exceeds a per-request limit.

Force model when you need it

When you need a specific model (e.g. "this customer is on Claude only"), use force model so the router skips selection and calls that model. You still get one endpoint, logging, and cost visibility—just with deterministic model choice.

Choosing the right strategy is the lever that keeps LLM cost control practical. StepBlend supports all of these plus cost caps and per-request overrides. Try the Optimizer → or see the routing API.