Helicone.
Single-line LLM observability proxy — Y Combinator alum, developer-first.
What it is.
Helicone is an LLM observability platform that ships as a one-line proxy change. Y Combinator S23 alum, open-source AGPL on GitHub, and used by ten thousand developers in production. Logs every request, tracks cost and latency by model and user, and offers built-in caching, rate-limiting, and prompt experimentation. The fastest path to production logging without rewriting client code.
Where it fits.
Teams that want observability without the LangSmith or Braintrust integration tax. The proxy model means you point your existing OpenAI or Anthropic SDK at Helicone and gain instant dashboards. Strong for startups, indie developers, and any team prioritising time-to-first-log over deep eval workflows.
- One-line proxy integration — no SDK rewrite
- AGPL open-source with self-hosted option
- Built-in caching and rate-limiting reduce inference spend
- Proxy architecture adds 10-30ms latency overhead
- Eval workflows lighter than LangSmith or Braintrust
Frequently asked.
How does the Helicone proxy work?
Change the base URL in your existing OpenAI or Anthropic SDK to Helicone's gateway. Every request is logged and forwarded with no code rewrite required.
Is Helicone GDPR compliant?
Yes. EU data residency available on Team and Enterprise tiers. Self-hosted deployment removes the residency question entirely.
When should I pick Helicone over LangSmith?
When integration speed matters more than deep agent-trace visualisation. Many teams run Helicone for cost monitoring and LangSmith for eval traces.
Open-source LLM engineering platform — Berlin-based, GDPR-clean by default.
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