Helicone

✓ Editorially verified

Open-source LLM observability — one-line proxy install.

Freemium· Free 100k req/mo; Pro from $25/moEvaluationPlatform (any LLM)8.3 / 10

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Best for

Pick Helicone when you want one-line LLM observability with no integration work.

Skip if

Skip it when you need deep eval datasets or your workload can't tolerate a proxy hop.

Helicone is open-source LLM observability with a brilliantly simple install — change your OpenAI base URL once, and you get logs, costs, caching, rate limits, and prompt observability for every API call. No SDK changes, no integration work, no instrumentation. Self-host or use Helicone Cloud.

For solo developers and small teams that want to see what's happening in their LLM calls without re-engineering their app, Helicone is the lightest-touch option in the eval/observability category. The free tier (100k requests/mo) is enough for most early-stage projects.

The eval and dataset features are less deep than Braintrust's or LangSmith's. Helicone is observability-first; if you need a serious eval workflow, you'll pair it with one of those tools rather than rely on Helicone alone. The proxy approach also adds a network hop, which a small number of latency-sensitive workloads find unacceptable.

Editor's take

Helicone is the answer to "I want to see what my app is spending and where it's slow" without writing a single line of integration code. For that specific goal it's near-unbeatable.

— The AI Tool Bible editorial team