No credit card · No account · No usage limits
Free.
Forever.
No asterisk.
LangSight is Apache 2.0 open source. Self-host the entire platform — CLI, SDK, API, dashboard, and every feature — at no cost. Not “open core”. Not a free tier. Just free.
$pip install langsight && langsight init
Self-hosted
Open Source
Free forever
$0forever · Apache 2.0
Get started →✓Unlimited agents, sessions, tool calls
✓Unlimited team members
✓Unlimited projects with RBAC
✓All CLI commands
✓Full REST API + dashboard
✓PostgreSQL + ClickHouse (dual-backend)
✓MCP health monitoring
✓Security scanning (OWASP + CVE)
✓Cost attribution + model pricing
✓Session replay + comparison
✓Anomaly detection + SLO tracking
✓AI root cause analysis (bring your key)
✓Self-hosted — your data, your infra
✓Apache 2.0 — fork, modify, embed freely
Managed cloud
Cloud
Coming soon
TBDusage-based pricing
○Everything in Open Source
○No infrastructure to manage
○Automatic backups + upgrades
○99.9% uptime SLA
○Enterprise SSO (SAML/OIDC)
○Priority support + SLA
○Dedicated Slack channel
○Custom data retention
○Usage-based — pay only for what you use
Get notified when cloud launches
Leave a GitHub star and we'll announce via releases.Star on GitHub →
Everything included
No feature gating. Ever.
Every capability listed below is available in the free open-source version. We will never move an existing feature to a paid tier.
Agent Observability
✓Full session traces — every tool call
✓Multi-agent call tree reconstruction
✓Payload capture (input args + output)
✓Session replay against live MCP servers
✓Side-by-side session comparison
✓LLM reasoning traces (llm_input / llm_output)
✓Anomaly detection (z-score vs 7-day baseline)
✓Agent SLO tracking (success_rate, latency_p99)
MCP Health Monitoring
✓Continuous proactive health checks
✓Schema drift detection
✓Latency tracking and p99 trends
✓Slack + webhook alerts on DOWN/recovery
✓Multi-transport: stdio, SSE, StreamableHTTP
MCP Security Scanning
✓CVE detection against public database
✓5 of 10 OWASP MCP checks (MCP-01, 02, 04, 05, 06 — more coming)
✓Tool poisoning detection (injection, unicode, base64)
✓Auth gap analysis
✓CI/CD integration with --ci flag
✓JSON output for SIEM integration
Cost Attribution
✓Token-based pricing for LLM calls
✓Per-tool call-based pricing rules
✓Cost per session / per agent / per tool
✓Model pricing table (admin-managed)
✓Historical cost trends
Infrastructure
✓PostgreSQL for metadata (users, projects, API keys, SLOs)
✓ClickHouse for analytics (spans, traces, costs, health)
✓Dual-storage architecture — routes each operation to the right backend
✓Docker Compose for self-hosted deployment
✓Alembic migrations for schema management
Teams & Access
✓Multi-user with invite-based signup
✓Project-level RBAC (owner / member / viewer)
✓API key auth with role scopes
✓Global admin + per-project roles
✓Audit trail for auth events
Cost comparison
$0 vs $2,000+/month
| What you need | LangSight | Datadog APM | New Relic |
|---|---|---|---|
| Monthly cost (10 services) | $0 | ~$2,400/mo | ~$1,800/mo |
| Agent action traces | ✓ Free | ✓ Paid | ✓ Paid |
| MCP health monitoring | ✓ Free | ✗ | ✗ |
| Security scanning | ✓ Free | ✗ | ✗ |
| Data leaves your network | Never | Always | Always |
| Vendor lock-in | None (Apache 2.0) | High | High |
| Custom retention | Unlimited | Pay per GB | Pay per GB |
FAQ
Common questions
Start now. It's free.
30 seconds to install. Two lines to instrument. No account required.