Definition

What it is

An open-source **AI gateway** (MIT-licensed) sitting between the agent runtime and foundation models. Provides observability (per-call traces persisted to S3), cost analytics, semantic caching, and unified routing across LLM providers. Repository: [github.com/Helicone/ai-gateway](https://github.com/Helicone/ai-gateway). The Helicone Gateway launch (June 2025) marked the open-source side of the model-gateway category catching up to managed-product alternatives.

Why it exists

AI workloads at production scale need observability that doesn't exist in the underlying provider APIs — per-request latency, cost attribution, prompt/response logging, semantic-cache hit rates, multi-provider failover decisions. Helicone wraps the gateway pattern with first-class observability that streams to durable S3-backed storage for downstream lakehouse analysis.

Primary use cases

Per-call LLM observability traces persisted to S3, cost attribution across multi-tenant agentic deployments, semantic caching with S3 backends, prompt/response auditing for compliance pipelines, model-routing decisions based on real-time cost/latency signals.

Recent developments

Latest signals

AI Gateway shipped as standalone Rust binary. Helicone's AI Gateway is a Rust-built, OpenAI-compatible unified API across 100+ models (OpenAI, Anthropic, Vertex, Groq, etc.) — "fastest, lightest, easiest-to-integrate" framing positions it as the leaner alternative to LiteLLM's Python proxy. Per GitHub — Helicone/ai-gateway.
Y Combinator W23 alum; open-source under MIT license. Helicone (the observability platform) and the AI Gateway are both MIT-licensed — full self-host path with no commercial restrictions. Per GitHub — Helicone/helicone.
SOC 2 + GDPR compliance for managed cloud. Enterprise tier passes the standard regulated-vertical compliance gauntlet — clears the same bar as Zep on the agent-memory side, lets Helicone get adopted in finance/healthcare alongside the OSS deployment for dev environments. Per Helicone — AI Gateway & LLM Observability.
10K free requests/month, no credit card. Generous free tier removes signup friction for dev evaluation — the standard "land then expand" SaaS pattern with the OSS escape hatch underneath. Per Helicone — AI Gateway & LLM Observability.
Native traces + sessions for agents, chatbots, document pipelines. Goes beyond per-call observability to multi-turn session traces — the abstraction that matches how agentic workloads actually behave. Per-trace cost/latency/quality metrics drive routing decisions back to the gateway. Per GitHub — Helicone/helicone.
LiteLLM ships an official Helicone integration. Cross-ecosystem interop — LiteLLM users can use Helicone as the observability backend without ripping out their gateway. Confirms the "Helicone for telemetry + LiteLLM for routing" pattern even as Helicone's own gateway grows. Per LiteLLM — Helicone integration docs.