Comet Opik vs Langfuse
Prices and features checked 2026-10-17 on both vendors' own pages. “not verified” means we could not confirm it.
Comet Opik or Langfuse? Both are open-source, self-hostable LLM tracing and evaluation platforms with cloud plans. Opik is Apache-2.0; its Free Cloud includes 25k spans and up to 10 members, and Pro Cloud is $19/month with 100k spans, then $5 per 100k. Langfuse's core is MIT; Hobby includes 50k units and 2 users, and Core is $29/month with 100k units and unlimited users, then $8 per 100k. Both support OpenTelemetry, CI runs, LLM-as-judge, annotation queues, prompt versioning and dataset versioning.
| Comet Opik | Langfuse | |
|---|---|---|
| Made by | Comet | Langfuse (ClickHouse, Inc.) |
| Licence | Apache-2.0 [source] | MIT for code outside the ee/ directories; ee/ code under a separate licence [source] |
| Self-hosting | Open-source version self-hosts with unlimited spans [source] | Free to self-host (Docker Compose or Kubernetes) [source] |
| Meter | Spans per month [source] | Billable units: traces, observations (spans, events, generations) and scores [source] |
| Free tier | Free Cloud: 25k spans/month, up to 10 team members, 60-day retention; open source self-hosted is free [source, checked 2026-10-17] | Hobby: 50k units/month, 30 days data access, 2 users [source, checked 2026-10-17] |
| Entry paid price | Pro Cloud $19/month: 100k spans, up to 50 members, then $5 per 100k spans [source, checked 2026-10-17] | Core $29/month: 100k units included, then $8 per 100k units (graduated down to $6 per 100k above 50M) [source, checked 2026-10-17] |
| Retention | 60 days on Free and Pro Cloud; unlimited when self-hosted; extension to 400 days at $29 per 100k spans [source] | Data access: 30 days (Hobby), 90 days (Core), 3 years (Pro and Enterprise) [source] |
| OpenTelemetry | Native OpenTelemetry support [source] | OpenTelemetry ingestion on all plans [source] |
| CI gating | PyTest integration for CI/CD [source] | Run experiments in CI and gate changes [source] |
| LLM-as-judge | LLM-as-judge and heuristic metrics [source] | LLM-as-judge evaluators on all plans [source] |
| Human annotation | Annotation queues [source] | Annotation queues: 1 on Hobby, 3 on Core, unlimited on Pro [source] |
| Prompt management | Prompt library and versioning [source] | Prompt versioning and release labels [source] |
| Dataset versioning | Dataset versioning [source] | Dataset versions are accessible via the SDK/API [source] |
| SOC 2 / HIPAA | SOC 2, ISO 27001, HIPAA and GDPR on Enterprise [source] | SOC 2 Type II and ISO 27001 reports and HIPAA (BAA) on Pro ($199/month) and Enterprise [source] |
Verdict: when to use which
Use Comet Opik if you want the lowest published cloud entry price, Apache-2.0 licensing for the whole codebase, or Opik's agent and prompt optimisation tools.
Use Langfuse if you need longer cloud history (90 days on Core, 3 years on Pro, against 60 days on Opik Cloud) or SOC 2 and HIPAA without going to an Enterprise contract (Langfuse Pro).
The meters differ, so price both on a week of your own traffic in the pricing calculator.
FAQ
How do the meters compare?
Opik counts spans. Langfuse counts units: traces, observations (spans, events, generations) and scores. The same app produces more Langfuse units than Opik spans, because traces and scores also count.
Is the open-source version the full product?
Comet says the open-source Opik is the same codebase as the hosted versions. Langfuse says it is open source and self-hostable; some enterprise features sit in its ee/ directories under a separate licence.
Compliance?
Opik lists SOC 2, ISO 27001, HIPAA and GDPR on Enterprise. Langfuse lists SOC 2 Type II, ISO 27001 and HIPAA on Pro and Enterprise.
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