Systems•2024
MultiLLM Proxy
Unified proxy server for multiple LLM providers with one consistent API.
Auth, rate limiting, streaming, monitoring, and provider health checks behind one gateway.
TL;DR
- Single endpoint that normalizes provider APIs.
- Routing policy with failover and caching for resilience.
- Operational visibility with structured logs and metrics.
Artifacts
Architecture diagram
Client -> proxy -> router -> provider adapters, with auth, rate limits, and cache.
Request trace view
Latency breakdown and fallback paths per request.
Context
Teams were shipping LLM features across multiple providers, each with different APIs, limits, and reliability characteristics.
Problem
Direct integrations created brittle code paths, inconsistent observability, and no safe way to switch providers during outages.
Approach
- Define a provider-agnostic request/response contract.
- Implement adapter modules per provider with retry and fallback logic.
- Enforce auth and rate limits at the edge.
- Add a Redis-backed cache keyed by model, prompt, and params.
- Instrument requests with trace IDs and structured logging.
Tradeoffs
- Kept the API surface to common features to avoid vendor lock-in.
- Used deterministic cache keys to keep results predictable.
- Chose Go for throughput, accepting a slightly slower iteration loop.
Testing and Reliability
- Contract tests with provider mocks.
- Load testing for streaming and concurrency.
- Replay suite for regression coverage.
Deployment and Ops
- Dockerized service deployable behind an API gateway.
- Environment-driven configuration for routing policies.
Outcome
- Simplified client integrations to one endpoint.
- Safer experimentation with routing policies.
- Lower tail latency for repeated prompts through caching.
If I had two more weeks
- Add budget-aware routing policies.
- Expose a lightweight policy dashboard.