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Traza and LangSmith

LangSmith is LangChain’s platform for tracing, evaluating and deploying agents. Traza is an open-source trace database that guards, replays and proves the runs it records. They overlap on tracing; here is where they differ, as each documents itself.

Last checked October 17, 2026

At a glance

	Traza	LangSmith
Source	Apache-2.0, the whole engine	A proprietary service; its client SDKs are open source
Self-hosting	Free: one binary and a data directory	An add-on to the Enterprise plan, with ClickHouse, PostgreSQL and Redis or Valkey (per its self-hosting docs)
OpenTelemetry ingest	OTLP/HTTP at `/v1/traces`, bearer API key	OTLP/HTTP at `/otel`, `x-api-key` header
Billing	Spans; never per seat	Traces, plus seats on Plus
First paid plan	Pro: $49 / mo, 20M spans / month	Plus: $39 / seat / mo, 10k base traces / mo, then $5.00 per 1,000 base traces
Retention	14, 30 or 90 days by plan; longer by contract	14 days for base traces; 180 days for extended traces, at extra cost

LangSmith facts from its pricing page (0.005 LSU per base trace at $1.00 per LSU), self-hosting docs and OpenTelemetry docs, read on October 17, 2026.

Traces and spans are different units

A LangSmith trace is one request with every step inside it. A Traza span is one step. A run of ten model and tool calls is one LangSmith trace and at least ten Traza spans, so compare a month of your own traffic in each unit, not the headline numbers. Our calculator takes spans.

LangSmith bills seats on Plus at $39 / seat / mo. Traza Cloud has no seat price on any plan; Pro and above include unlimited members.

Choose Traza when

You want to run it yourself, free. The same engine Traza Cloud runs is Apache-2.0 and one binary.
You need to stop runaway runs. Run fuses with a pre-call check, a verdict on every acknowledgement and a kill switch. Guard
You want to replay runs without model calls, through the OpenAI or Anthropic SDK, with strict divergence detection. Replay
You answer to auditors. A hash-chained ledger, evidence packs and erasure receipts, with notary signatures on Team. Prove
Your framework is not LangChain, or is several. Traza reads OpenLLMetry, OpenInference and GenAI-convention spans from any OpenTelemetry SDK.

Choose LangSmith when

You build on LangChain or LangGraph and want tracing that comes with the framework.
You want evaluation in the same product: online and offline evals, dataset collection, annotation queues and a Prompt Hub and playground.
You also want hosting for the agents themselves. LangSmith Deployment runs agents; Traza only records them.
You need longer cloud retention per trace without an enterprise contract: extended traces keep 180 days.