Fly.io vs LangSmith

Fly.io

LangSmith

Fly.io · 14 features

• Auto Stop/Start — Machines auto-stop when idle, start on request (like scale-to-zero).
• Certs — Let's Encrypt + wildcard certs managed.
• Fly GPU — A100/L40S/A10 on-demand GPU machines.
• Fly Kubernetes (FKS) — Managed Kubernetes on Fly machines.
• Fly Machines — Firecracker microVMs. Start in <1s. Run any Docker image.
• Fly Postgres — Managed Postgres via Supabase partnership (2024). Also legacy self-run Postgres …
• fly-replay headers — Route request to another region at app level.
• Fly Volumes — Persistent SSD attached to a Machine. Encrypted at rest.
• Global Anycast — Single IP routes to the closest region automatically.
• LiteFS — Distributed SQLite with primary/replica across regions.
• Private Networks — 6PN WireGuard mesh. Connect machines across regions privately.
• Secrets — Encrypted env vars propagated to all regions.
• Tigris (partner) — S3-compatible storage for Fly apps. By partner.
• Upstash Redis (partner) — Managed Redis via Upstash.

LangSmith · 14 features

• Alerts — Threshold alerts on latency, cost, eval metrics.
• Annotation Queues — Human-review workflows for trace quality rating.
• Custom Dashboards — Aggregate metrics dashboards per project/tag.
• Datasets — Collect examples → use as eval sets or training data.
• Evaluations — LLM-as-judge, embedding similarity, custom Python evaluators, offline batch eval…
• LangChain Integration — Auto-trace any LangChain/LangGraph run with env var.
• LangGraph Integration — First-class trace + eval for LangGraph agents.
• LLM Tracing — Automatic trace every LLM call + tool call + chain step.
• OpenTelemetry Export — Export traces as OTLP to Datadog/Honeycomb/etc.
• Playground — Test prompts + models inline before deploying.
• Prompt Canvas — Visual prompt editor with live test + eval.
• Prompt Hub — Public + private prompt library with versioning.
• Self-Hosted (Enterprise) — Docker + k8s deployment in your infra.
• Threads + Sessions — Group traces into conversational sessions.