Langfuse Review: Open-Source LLM Observability and Cost Tracking
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Langfuse is an open-source observability tool for AI applications. It is not a gateway. It records what your app sends and receives so you can see where tokens and money go.
How it works
You add a small piece of code to your app. Langfuse then records traces of each request, including prompts, responses, latency and cost, and lets you track prompt versions. It can also receive logs from gateways such as LiteLLM.
Cost-saving tools
Tools like these can automate several of the steps above.
TRY LANGFUSE AND OTHER TOOLSStrengths
- Clear cost and usage views by feature and model
- Prompt tracking and tracing help you debug and improve
- Can be self-hosted or used as a hosted service
Limits
- It shows costs but does not enforce budgets by itself
- You need to add instrumentation to your code
Who it fits
Teams that want to understand which prompts and features cost the most.
Our rating
- Savings potential7
- Ease of setup7
- Cost transparency8
- Maturity8
Editorial score from public documentation and our stated criteria. It is an opinion, not a lab test; check the vendor for current features and pricing.
Verdict
Excellent for finding waste. Pair it with a gateway if you also want to enforce limits.
Features, ownership and pricing of AI tools change quickly. Check the official site before you decide.