Trace, evaluate and improve applications
LangSmith comparison0%
vs AI engineering platform
Flowlines vs LangSmith.
Flowlines is not a LangSmith replacement. LangSmith combines tracing, online and offline evaluation, prompt engineering, and deployment workflows. Flowlines connects through read-only project polling or LangSmith OpenTelemetry export and specializes in recurring behavior issues, affected users, and MCP journeys.
LangSmith records traces and threads, supports online and offline evaluations, and connects production failures back to datasets and experiments. It covers a broad AI application lifecycle.
Flowlines works one level up. It imports LangSmith runs through read-only API polling or receives them through OpenTelemetry export, then answers questions a single trace can't: what is not working, who is affected, which recurring intents are involved, and which production sessions share the pattern. You don't replace LangSmith. You connect it.
Head to head
01Primary job
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Explain production behavior
02Trace capture
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Native traces, runs and threads
Imports or receives traces for analysis
03Online and offline evals
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Yes
Not an eval platform
04Cross-session analysis
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Threads, online evals and metadata
Recurring issues, users and intents
05MCP and tool analysis
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Traces and trajectory evaluation
Dedicated server, tool and journey views
06Investigation path
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Trace, run and evaluator result
Issue to affected users and sessions
07Integration
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LangSmith SDK or OTEL
Read-only polling or LangSmith OTEL export
Bottom line
Use LangSmith for broad tracing, online and offline evaluation, and application development workflows. Use Flowlines for an opinionated view of recurring production behavior, affected users, and MCP journeys. They're complementary. Connect LangSmith by polling one project or mirror runs through its OpenTelemetry export.
Sources reviewed / September 2026
Use Flowlines with your assistant