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Looptail as a Langfuse alternative
Langfuse is the open-source leader in LLM observability, and since January 2026 it is part of ClickHouse. If you're re-evaluating after the acquisition — or you've realized you need evidence, not just traces — here's an honest comparison.
Where Langfuse wins
If you must run everything in your own VPC today, use Langfuse — self-hosting is its home turf and Looptail doesn't offer it. Its tracing is mature, its community is large, and the ClickHouse acquisition likely strengthens its analytics backbone. If what you need is best-in-class traces at open-source prices, it's a good choice and we won't pretend otherwise.
Where Looptail is different
Looptail is built around a different question. Not "what did my system do?" but "can I prove what it did, how it was judged, and what changed?" Every decision becomes a signed, append-only record tied to its evaluation and the fix that followed —the Tail — and the improvement loop that generates those records also ships the fixes, through replay, canary, and approval gates.
| Langfuse | Looptail | |
|---|---|---|
| Open source | Core platform is open source (MIT-licensed components); large community | Open SDK; hosted platform; trail format publishing as an open spec |
| Self-hosting | Yes — a primary strength | No. Hosted, with EU data residency on Enterprise |
| Tracing & observability | Mature, framework-agnostic tracing | Full decision capture: inputs, context, tool calls, outcomes |
| Evals | Eval tooling on traces and datasets | Continuous rubric evaluators on live traffic, versioned like code |
| Automated improvement | Not a product focus | Patch proposals, replay against regression sets, canary, approval gates |
| Signed audit trail | No — logs and traces, mutable stores | Append-only, hash-chained, signed; verifiable from the CLI |
| Compliance evidence export | Manual, via APIs | Dated, self-verifying evidence packs; EU AI Act-oriented |
| Price of entry | Free (self-hosted OSS); paid cloud tiers | Free tier: 10k loop events/mo, 30-day retention, export |
Comparison reflects public information as of July 2026. Spot an error?Tell us and we'll fix it.
If you're a self-hoster weighing the acquisition
Ask the questions you'd ask any acquired project: what's the roadmap for the self-hosted edition, which features land cloud-first, and what does the license look like in two years. If the answers work for you, stay. If your real requirement was never "self-hosted" but "my data provably intact and portable," that's a different requirement — and it's the one Looptail was built for. Your trail exports on every tier, in a format we're publishing as an open spec.
Run both, honestly
Teams keep their tracing tool and add Looptail for evals, improvement, and evidence. The SDK sits alongside existing instrumentation; nothing has to be ripped out to geta signed trail running in 10 minutes.