Apps similar to Spanlens include Langfuse, which has a free version. Other options are Helicone, Opik, Corrath and SignalVault. In total there are seven Large Language Model (LLM) Tools like Spanlens for the web and self-hosting.
Open source LLM engineering platform: LLM Observability, metrics, evals, prompt management, playground, datasets. Integrates with OpenTelemetry, Langchain, OpenAI SDK, LiteLLM, and more.
Germany
EU
Helicone is the open-source LLM observability platform for developers to monitor, debug, and improve production-ready applications.
United States
Opik is an open-source platform for evaluating, testing and monitoring LLM applications. Built by Comet.
Corrath is an AI security gateway built for developers and organizations building with Large Language Models.
India
Proxy that logs every LLM prompt, response and tool call to an encrypted audit trail, and blocks or flags requests carrying PII, secrets or policy violations before they reach the provider.
SwedenEU
LLMCap is a reverse proxy that enforces real-time, dollar-based spending caps on LLM API calls. When you hit your cap, the next request returns 429 — the token is never consumed and money is never spent.
Canada
Glassbrain captures every step of your AI app as an interactive visual trace tree. Click any node, swap the input, replay instantly without redeploying. Snapshot mode stores deterministic replays. Live mode hits your actual stack.
India
