LLM caching architecture

LLM caching: exact responses, prompt caching and semantic reuse

“LLM cache” can describe very different systems. Exact response caching reuses an identical deterministic result, provider prompt caching reuses model work for a repeated prefix, and semantic caching may return a previous result for a similar request. Each has different quality, privacy and invalidation risks.

Results vary by workload. Provider prices and limits remain controlled by the provider.

Exact response cache

Exact caching is safest when the request is deterministic, permissions are isolated and the response remains valid. Cache keys must include every input that changes behavior. Tenant isolation and expiration rules are essential.

Provider prompt cache

Prompt caching is controlled by the model provider and reported through provider usage. It can help large stable prefixes without returning an old answer. Eligibility and pricing vary by model.

Local token estimate

This is an approximate comparison, not provider billing data.

Semantic cache

Varion keeps its proprietary engine implementation private. Commercial evaluation is based on measurable workload-specific outcomes, clear validation boundaries and customer-specific testing rather than disclosure of internal mechanisms. Use the dedicated Token Optimisation product area to evaluate whether the commercial result is suitable for your traffic; no universal performance percentage is promised.

Measurement checklist

  1. Choose a representative completed task, not an artificial one-line prompt.
  2. Record the selected model, provider input, cached input, output, retries and final result.
  3. Change one optimization mechanism at a time so the cause remains visible.
  4. Verify required identifiers, tool calls, code changes or business fields.
  5. Keep passthrough available when the reduced request does not pass.

Varion commercial evaluation

Varion keeps proprietary product implementation details private. Evaluate Token Optimisation on representative traffic and judge it by the measured commercial result. New verified users receive 100,000 processed input tokens and 50 local test runs.

Frequently asked questions

Which cache is safest?

Exact caching of a fully identical, permission-safe request is easier to reason about than semantic reuse, but every system still needs invalidation and isolation.

Does an LLM cache reduce input tokens?

An exact response cache can avoid the provider call. Prompt caching changes provider processing or price. Context reduction sends fewer tokens.