Flowlines vs Langfuse.
Flowlines is not a Langfuse alternative, Langfuse is one of its inputs. Langfuse stores your agent's traces; Flowlines connects to Langfuse with API keys and adds behavioral signals, cohorts, and version analysis on top. Keep Langfuse, add Flowlines.
Langfuse is a trace store: it captures and persists your LLM and agent traces and gives you call-level debugging. It's a great place for your data to live, and it's the most common way teams connect to Flowlines.
Flowlines is the analysis layer that sits on top. It reads your Langfuse traces (API keys, ~5 minutes, no SDK) and turns them into behavioral signals across sessions, behavioral cohorts of users, and before/after comparisons for every prompt version. This is the clearest “not versus, on top of” relationship on this page.
If you have Langfuse, you're ~5 minutes from Flowlines: connect with API keys and the last 30 days backfill immediately. Langfuse keeps your traces; Flowlines tells you what they mean across users, versions, and time.