Helicone

Helicone is an LLM observability platform and AI gateway. Its sweet spot is request-level visibility: what model was called, how long it took, what it cost, which user or feature triggered it, and where latency or spend is getting out of hand.

For a solo founder building an AI product, Helicone is useful before the agent stack gets complicated. You can route traffic through it, get cost and latency visibility, and stop flying blind on the first production usage. That matters because agent cost is not just tokens; retries, tool calls, and long conversations can change the unit economics fast.

The honest limitation is that Helicone is lighter than a dedicated agent eval platform. It can show you the request story, but you may still need Braintrust, Langfuse, Phoenix, or LangSmith when the question becomes “did the agent choose the right tools and complete the whole workflow?” Start here for cost and API visibility; graduate when workflow quality becomes the main risk.