Arize Phoenix vs SigNoz
Both are observability & tracing tools. Here is how they actually differ on price, billing model and deployment.
Arize Phoenix
The default open-source choice for LLM tracing and eval - runs locally in under a minute, built on OpenTelemetry. The catch is the license - the server is Elastic License 2.0, source-available, not OSI open source.
SigNoz
An open-source Datadog alternative that handles LLM telemetry as part of full-stack observability rather than as a separate product. Free to license, but you are running ClickHouse - the cost is infrastructure and ops, not fees.
| Arize Phoenix | SigNoz | |
|---|---|---|
| Category | Observability & Tracing | Observability & Tracing |
| Our rating | 4/5 | 4/5 |
| Starting price | $0 | $19/mo (startup) or $49/mo |
| Billing meter | No usage metering | gb-ingested |
| Free plan | Yes | Yes |
| Free self-hosting | Yes, free | Yes, free |
| Best for | Teams that want fast, framework-agnostic OSS tracing and strong RAG eval, and who are not reselling Phoenix as a hosted service | Teams that want one observability backend for their whole stack rather than a separate LLM tool, are cost-sensitive relative to Datadog, and either have ClickHouse operational capacity or will pay for cloud. |
Our verdict on Arize Phoenix
The default open-source pick for good reasons - it starts in under a minute, the RAG eval is the best around, and it is built on OpenTelemetry so you are not locked to one framework. Just read the license before you build a business on it. The server is Elastic License 2.0, source-available rather than OSI open source, which only bites if you plan to offer Phoenix as a service - but it is not what "fully open source" implies.
Full Arize Phoenix review →Our verdict on SigNoz
SigNoz is the right answer to a question many teams are actually asking - not "which LLM observability tool" but "how do I see my LLM calls alongside everything else without paying Datadog prices." It handles LLM telemetry as one workload within full-stack observability, giving token-level tracing, per-model cost attribution and prompt latency breakdown, all correlated with the databases and microservices underneath. It is genuinely open source and self-hostable with no feature gating. Two honest caveats. Self-hosted free covers the license and nothing else - you are operating ClickHouse, which is resource-hungry, and you inherit the on-call burden of your own monitoring stack going down. And there is no evaluation capability whatsoever, so if you need LLM-as-judge scoring, datasets or regression testing, SigNoz is half your stack and you will pair it with something like DeepEval or promptfoo.
Full SigNoz review →Frequently Asked Questions
What is the main difference between Arize Phoenix and SigNoz?
Arize Phoenix: Teams that want fast, framework-agnostic OSS tracing and strong RAG eval, and who are not reselling Phoenix as a hosted service SigNoz: Teams that want one observability backend for their whole stack rather than a separate LLM tool, are cost-sensitive relative to Datadog, and either have ClickHouse operational capacity or will pay for cloud. Both sit in Observability & Tracing, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, Arize Phoenix or SigNoz?
It depends entirely on your workload shape, because they meter differently - Arize Phoenix bills on no usage metering and SigNoz bills on gb-ingested. Published starting prices are $0 and $19/mo (startup) or $49/mo respectively, but those numbers are not comparable until you apply them to the same traffic. Use our cost calculator to model both against your own request volume and span count.
Can I self-host Arize Phoenix or SigNoz?
Arize Phoenix: Yes, free. SigNoz: Yes, free. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.