Head-to-Head Comparison · Alternative to LangSmith · 📊 analytics
LangSmith vs Spanlens
Drop-in observability platform for OpenAI, Anthropic, and Gemini that logs every request, tracks costs, traces agent workflows, and flags anomalies and PII. Here is how Spanlens ($0/mo open source) stacks up against LangSmith ($35/mo) across cost, hosting, data privacy, and real-world trade-offs.
Spanlens is a verified Open Source-licensed open-source replacement for LangSmith. Switching from LangSmith ($35/mo) saves $420/yr per solo seat, or $2,100/yr for a 5-person team. Deployment: Runs on Self-host.
The catch: Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
Spanlens
$0.00/mo · Open Source
LangSmith vs Spanlens Specifications
facts verified 2026-11-07
| Dimension | LangSmith (Paid) | Spanlens (Replacement) |
|---|---|---|
| Monthly Price | $35 / mo | $0 / mo |
| 1-Year Cost (1 seat) | $420 / yr | $0 / yr (Save $420) |
| 1-Year Cost (5 seats) | $2,100 / yr | $0 / yr (Save $2,100) |
| 1-Year Cost (10 seats) | $4,200 / yr | $0 / yr (Save $4,200) |
| Source & License | Proprietary SaaS | open source Open Source |
| Where It Runs | Vendor Cloud | Self-host (your server) |
| Platforms | Web / Cloud | webself-hosteddocker to self-host |
| GitHub Stars | — | ★ 13 (active nov 2026) |
Deep Dive: Switching from LangSmith to Spanlens
Trade-offs, installation & data architecture
What you trade away
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
How to deploy Spanlens
Clone https://github.com/spanlens/Spanlens or deploy with Docker Compose
What it takes to run
Deploy via Docker or binary release from GitHub and configure environment variables.
Where your data lives
All application data and configuration live on your own server or local database.
Why fork Spanlens instead of vibe-coding a LangSmith clone?
Instead of paying recurring SaaS fees for LangSmith or rebuilding it from scratch, deploy one of the 8 battle-tested open-source alternatives like Langfuse.
LangSmith vs Spanlens FAQ
Is Spanlens a good free alternative to LangSmith?+
Yes. Spanlens is a verified open-source (Open Source) replacement for LangSmith. Drop-in observability platform for OpenAI, Anthropic, and Gemini that logs every request, tracks costs, traces agent workflows, and flags anomalies and PII.
What is the catch when switching from LangSmith to Spanlens?+
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
How much do you save switching from LangSmith to Spanlens?+
LangSmith costs $35/mo ($420/yr) per seat, whereas Spanlens is $0/mo. Switching saves $420/yr for a solo user, $2,100/yr for a 5-person team, and $4,200/yr for a 10-person team.
How do I install or self-host Spanlens instead of LangSmith?+
Install: Clone https://github.com/spanlens/Spanlens or deploy with Docker Compose. Setup: Deploy via Docker or binary release from GitHub and configure environment variables.
