Compare tools side by side · TechInTrends

Open-source AI observability and evaluation tool built on OpenTelemetry and OpenInference.

Open-source LLM engineering platform for traces, evals, prompt management and metrics; now part of ClickHouse.

LangChain's hosted platform for tracing, evaluating and monitoring LLM apps and agents, framework-agnostic.

Evaluation-first AI platform where production traces become datasets and regression tests.

Head to head

Metric	Arize Phoenix	Langfuse	LangSmith	Braintrust
Stars	12.2k	37.3k	n/a	n/a
Weekly downloads	117k	7.4M	21.2M	3.2M
Download growth	-4%	+32%	+19%	+63%
Popularity score	68/100	84/100	90/100	80/100
Forks	1.3k	4.2k	n/a	n/a
Open issues	1.2k	1.2k	n/a	n/a
Last commit	4d ago	today	n/a	n/a
Latest version	21.0.0Oct 30, 2026	5.2.0Nov 5, 2026	0.14.17Nov 2, 2026	3.44.0
First released	2022	2023	n/a	n/a
Signals	None	TrendingPopular	Popular	Rising
Listed in	AI & Machine Learning › LLM Observability & Evals	AI & Machine Learning › LLM Observability & Evals	AI & Machine Learning › LLM Observability & Evals	AI & Machine Learning › LLM Observability & Evals

Weekly downloads over time

Hover for exact values; switch to log scale for tools of very different sizes. Not shown (no comparable download data): Braintrust.

Arize Phoenix
Langfuse
LangSmith