Helicone API
Helicone API
Helicone API is an LLM observability tool — one-line proxy integration to trace, monitor, cache, rate-limit any OpenAI / Anthropic call.
Extremely simple integration (change base_url, one line)
Proxy mode adds small latency (~50ms)
Sign up at helicone.ai for API key. OpenAI SDK: client.base_url = "https://oai.helicone.ai/v1"; headers["Helicone-Auth"] = "Bearer ..."
Uptime · 30-day window
About this API
Helicone is a 2023 YC LLM observability startup. Different path from LangSmith: LangSmith instruments code via SDK; Helicone uses proxy — just change OpenAI base_url to Helicone proxy URL, all LLM calls auto-trace without changing other code. This "one-line integration" is its killer feature, especially for projects not using LangChain. Function coverage: complete request trace (per-call prompt, response, cost, latency), cost dashboard, cache (same prompt auto-hits cache to save tokens), rate limit (prevent abuse), user-level analytics, A/B testing prompt versions. Open-source (Apache 2.0), self-hostable. Smaller ecosystem than LangSmith but fast-growing, especially in startup circles.
What you can build
- 1LLM app monitoring (cost / latency / error rate)
- 2Quickly trace LLM calls for debugging
- 3Cache repeated prompts to save cost
- 4Rate limit to prevent abuse
Strengths & limitations
Strengths
- Extremely simple integration (change base_url, one line)
- Generous free tier 100k requests/month (more than LangSmith)
- Supports all LLM providers (not limited to LangChain)
- Open-source (Apache 2.0)
Limitations
- Proxy mode adds small latency (~50ms)
- Eval framework less complete than LangSmith
- Ecosystem smaller than LangSmith
Official quickstart
Read the official quickstart at docs.helicone.ai.
Getting started
Sign up at helicone.ai for API key. OpenAI SDK: client.base_url = "https://oai.helicone.ai/v1"; headers["Helicone-Auth"] = "Bearer ..."
FAQ
Helicone proxy latency?+
Generally under 50ms. Global deployment + edge workers — negligible for most apps.
Can I self-host?+
Yes. Open-source (Apache 2.0), docker-compose runs locally in a few commands.
Technical details
- Auth type
- api_key
- Pricing
- freemium
- Rate limit
- 免费 100k requests/月
- Protocols
- REST
- SDKs
- python, typescript, javascript
- Response time
- 83 ms
- Last health check
- 6/26/2026, 6:23:36 AM