Staxly

PostHog vs LangSmith

Open source product analytics — all-in-one dev tool
vs. LLM observability, testing & evaluation — by LangChain

PostHog websiteLangSmith website

Pricing tiers

PostHog

Free (generous)
No credit card. Each product has its own free monthly quota. Great for startups + OSS.
Free
Paid (usage-based)
Pay only what you use, after free quotas. Volume discounts at higher tiers. 6 projects, 7-year retention.
$0 base (usage-based)
Self-Hosted (OSS)
MIT-licensed. Run on your own infra via Docker/k8s. Zero vendor lock-in.
$0 base (usage-based)
Enterprise
Custom. SAML SSO, dedicated CSM, custom SLA.
Custom
PostHog website

LangSmith

Developer (Free)
Free forever. 5,000 traces/month. 14-day retention. 1 seat. Basic evaluations.
Free
Plus
$39/seat/month. 10k base traces included ($2.50 per 1k overage). Full evaluations, custom dashboards, email support.
$39/mo
Enterprise
Custom. Self-host option, SSO, custom retention, dedicated support.
Custom
LangSmith website

Free-tier quotas head-to-head

Comparing free on PostHog vs developer on LangSmith.

MetricPostHogLangSmith
data warehouse rows1000000 rows/month
error tracking exceptions100000 exceptions/month
feature flags requests1000000 requests/month
llm analytics events100000 events/month
logs gb50 GB/month
product analytics events1000000 events/month
projects1 projects
retention years1 year
session replay recordings5000 recordings/month
surveys responses1500 responses/month
team membersunlimited members

Features

PostHog · 14 features

  • A/B TestingExperiments with significance analysis.
  • Data PipelinesExport events to BigQuery, Snowflake, S3.
  • Data WarehouseQuery external sources (Stripe, Hubspot, S3) alongside events with SQL.
  • Error TrackingSentry-style error tracking in same platform.
  • Feature FlagsRollout flags with targeting, A/B testing, JSON payloads.
  • LLM AnalyticsTracing + cost tracking for OpenAI, Anthropic, Gemini, etc.
  • LogsCentralized log ingest with free 50 GB/month.
  • Product AnalyticsEvents, funnels, trends, retention, paths. SQL insights available.
  • Revenue TrackingIntegration with Stripe for revenue + churn metrics.
  • Self-HostingDocker/Helm. Full feature parity with cloud.
  • Session ReplayWatch user sessions. Privacy controls, masked inputs, JS errors.
  • SQL Query APIRun ClickHouse SQL over your events via API.
  • SurveysIn-app surveys + feedback widgets.
  • WorkflowsTrigger emails/webhooks on events.

LangSmith · 14 features

  • AlertsThreshold alerts on latency, cost, eval metrics.
  • Annotation QueuesHuman-review workflows for trace quality rating.
  • Custom DashboardsAggregate metrics dashboards per project/tag.
  • DatasetsCollect examples → use as eval sets or training data.
  • EvaluationsLLM-as-judge, embedding similarity, custom Python evaluators, offline batch eval
  • LangChain IntegrationAuto-trace any LangChain/LangGraph run with env var.
  • LangGraph IntegrationFirst-class trace + eval for LangGraph agents.
  • LLM TracingAutomatic trace every LLM call + tool call + chain step.
  • OpenTelemetry ExportExport traces as OTLP to Datadog/Honeycomb/etc.
  • PlaygroundTest prompts + models inline before deploying.
  • Prompt CanvasVisual prompt editor with live test + eval.
  • Prompt HubPublic + private prompt library with versioning.
  • Self-Hosted (Enterprise)Docker + k8s deployment in your infra.
  • Threads + SessionsGroup traces into conversational sessions.

Developer interfaces

KindPostHogLangSmith
CLILangSmith CLI
SDKposthog-android, posthog-flutter, posthog-go, posthog-ios (Swift), posthog-js, posthog-node, posthog-php, posthog-python, posthog-react-native, posthog-rubylangsmith-js, langsmith-python
RESTPostHog REST APILangSmith REST API
MCPPostHog MCPLangSmith MCP
OTHERWebhooks + ActionsLangSmith Dashboard
Staxly is an independent catalog of developer platforms. Some links to PostHog and LangSmith may be affiliate links — Staxly may earn a commission if you sign up through them, at no extra cost to you. Pricing is verified against vendor pages at publication time — reconfirm before buying.

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