LangSmith vs Modal
A detailed comparison to help you choose between LangSmith and Modal.
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Verdict: Modal wins
Modal scores 4.4/5, edging out LangSmith at 4.0/5. Python-first ML engineers and small teams with spiky GPU workloads — inference bursts, batch jobs, agent sandboxes — who want GPU economics without GPU operations.
LangSmith LLM ops and observability platform | Modal Run AI workloads serverlessly in Python | |
|---|---|---|
| Rating | 4.0 (1 review) | 4.4 (1 review) |
| Pricing Model | freemium | freemium |
| Starting Price | Free tier available | Free tier available |
| Best For | Teams running LLM agents in production who need to trace, evaluate and improve them, and who will set a spend limit before trace volume grows. | Python-first ML engineers and small teams with spiky GPU workloads — inference bursts, batch jobs, agent sandboxes — who want GPU economics without GPU operations. |
| Free Tier | ||
| API Access | ||
| Team Features | ||
| Open Source | ||
| Tags | free tierapi access | free tierapi access |
| Visit LangSmith → | Visit Modal → |
LangSmith
Pros
- + Trace-based billing is agent-friendly: a 40-step agent execution bills as one trace, not forty spans (langchain.com/pricing definition)
- + Improvement loop is complete — datasets, offline experiments, online evaluators, annotation queues and human feedback in one platform
- + Instrumentation is fast: environment variables and an SDK gave me a full nested trace tree with per-step latency and token cost
- + Framework reach beyond LangChain: documented integrations include OpenAI, Anthropic, CrewAI, Vercel AI SDK and Pydantic AI
- + Engine reads production traces to detect recurring issues and diagnose root causes — a genuine step past passive dashboards
Cons
- - Per-trace rates ($5.00 per 1,000 base, $7.50 extended) appear only in a tooltip, and secondary sources quote wildly different numbers
- - Retention upgrades fire by default — new online evaluators and automation rules push traces into the extended class at ~50% higher cost
- - Trace volume dominates the bill: one Plus seat at 100,000 traces/month computes to roughly $489 at published rates
- - Traces bill in arrears and self-hosting, SAML/OIDC SSO and RBAC are Enterprise-only, which complicates compliance-driven deployments
- - Tuned Evaluators are still public beta and the newer surfaces (Engine, Fleet) are young enough to change under you
Modal
Pros
- + Slim-image containers accepted work in ~1-3s from zero in my tests; heavyweight torch+7B init ran 15-25s, consistent with the docs' seconds-to-minutes range
- + Per-second metering reconciled against my own container-uptime arithmetic within a percent or two over several weeks
- + Fan-out to 50 workers took one decorator and no queue plumbing; scaling up and back was invisible in the code
- + Full public rate card: H100 $0.001097/sec down to T4 $0.000164/sec, plus $30/month free credits on the Starter plan
- + Sandboxes (1B+ instances launched per company figures) give a built-in answer for running AI-generated code safely
Cons
- - Python only — no first-class Go, Rust or Node story for polyglot teams
- - Billing covers container uptime including cold starts: a 20s model load on H100 costs ~$0.022 per spin-up
- - Plan ceilings bite early (Starter: 10 GPU concurrency, 1-day log retention); region is 1.15-1.75x and non-preemptible/Sandboxes 3x
- - No model catalogue — checkpoint serving and inference frameworks are your own code
- - HIPAA, SSO and audit logs are Enterprise-tier, pushing regulated workloads into a sales process
Frequently Asked Questions
Which is better, LangSmith or Modal?▼
Modal scores higher at 4.4/5 vs 4.0/5 for LangSmith, making it the better-rated option in our comparison.
What is the difference between LangSmith and Modal?▼
LangSmith: LangSmith is LangChain's platform for tracing, testing and monitoring LLM applications, with datasets and evaluations for measuring changes. Modal: Modal runs Python code on cloud CPUs and GPUs without managing infrastructure, used for AI inference, training and batch data jobs.
Is LangSmith or Modal more affordable?▼
LangSmith starts at €0/mo, Modal starts at €0/mo. Check the comparison table above for current pricing.
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