LLM observability (13)
Each tool bills a different unit (units, traces, spans, records, GB). The calculator treats one request as one unit; read the caveat on the calculator page.
| Product | Licence | Self-host | Entry | Free tier | Main source |
|---|---|---|---|---|---|
| Langfuse | MIT core; self-host | yes (MIT) | from $29/mo | Hobby: 50k units a month | OFFICIAL |
| LangSmith | commercial | no | from $39 per seat/mo | Developer: 1 seat, 5k base traces a month | OFFICIAL |
| Arize AX / Phoenix | Phoenix open source; AX commercial | Phoenix: yes | from $50/mo | AX Free: 25k spans a month | OFFICIAL |
| Datadog LLM Observability | commercial | no | from $160/mo | Free tier: up to 40K LLM spans a month, 15-day retention | OFFICIAL |
| Pydantic Logfire | commercial (SDK open source) | no | from $49/mo | Personal: 10M records a month, hard-capped at $0 | OFFICIAL |
| Opik (Comet) | open source; self-host free | yes | from $19/mo | Free Cloud: 25k spans a month | OFFICIAL |
| Braintrust | commercial | no | free tier / open source | Free: 1 GB, 10K scores, 14-day retention | OFFICIAL |
| Galileo | commercial | no | free tier / open source | Free: 5,000 traces a month (third-party reports; vendor page no longer lists prices) | OFFICIAL |
| Confident AI | commercial | no | from $200/mo | Free: 2 seats, 1 GB-month trace data | OFFICIAL |
| Fiddler | commercial | no | free tier / open source | Free guardrails plan (demo request) | OFFICIAL |
| W&B Weave | commercial | no | free tier / open source | Free: 1 GB Weave ingestion a month | OFFICIAL |
| Maxim AI | commercial | no | free tier / open source | Developer: 3 seats, 10k logs a month | OFFICIAL |
| Prefactor | commercial | no | from $49/mo | Dev: 5,000 spans a month | OFFICIAL |