Spanlens
Open-source LLM observability: log cost, latency, tokens
About Spanlens
What Spanlens does
AINave analysisDevelopers monitor and analyze the cost, latency, tokens and traces of their application's calls to large language model providers.
- Best for
- Developers building LLM-powered featuresEngineering teams running LLM workloads in production
- Use it to
- Tracking model spend per model and project
- Debugging slow or failing agent runs with nested traces
- Comparing prompt versions on quality, cost and latency
- Running evaluations in CI and gating merges on scores
- Detecting cost spikes and error bursts with alerts
- Self-hosting request logging for private workloads
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