SigNoz vs Datadog LLM Observability
Both are observability & tracing tools. Here is how they actually differ on price, billing model and deployment.
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.
Datadog LLM Observability
LLM tracing bolted onto the Datadog APM platform. Bills per LLM span rather than per trace, which is the single most misunderstood thing about it - agentic workloads can burn the 40,000-span free tier in a day.
| SigNoz | Datadog LLM Observability | |
|---|---|---|
| Category | Observability & Tracing | Observability & Tracing |
| Our rating | 4/5 | 3/5 |
| Starting price | $19/mo (startup) or $49/mo | $160/mo |
| Billing meter | gb-ingested | span |
| Free plan | Yes | Yes |
| Free self-hosting | Yes, free | No or paid tier only |
| Best for | 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. | Teams already standardised on Datadog for infrastructure and APM, running LLM features inside a larger system, who value one pane of glass over best-in-class eval tooling and can model their span volume accurately. |
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 →Our verdict on Datadog LLM Observability
Datadog LLM Observability is the obvious pick if Datadog is already your monitoring platform, and a poor one otherwise. The correlation story is real - being able to trace an LLM latency spike down through the service, host and database in one product is something no AI-native competitor matches. The eval tooling is competent but not the reason you would buy it. The thing that decides this product is billing. Datadog charges per LLM span, not per trace, and that distinction is where teams get hurt. A simple completion is 3 to 5 spans, but an agentic workflow with tool calls, retrieval and reasoning chains is commonly 20 to 50. Estimate your bill from requests and you will be wrong by more than an order of magnitude. Model span volume first, then decide.
Full Datadog LLM Observability review →Frequently Asked Questions
What is the main difference between SigNoz and Datadog LLM Observability?
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. Datadog LLM Observability: Teams already standardised on Datadog for infrastructure and APM, running LLM features inside a larger system, who value one pane of glass over best-in-class eval tooling and can model their span volume accurately. Both sit in Observability & Tracing, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, SigNoz or Datadog LLM Observability?
It depends entirely on your workload shape, because they meter differently - SigNoz bills on gb-ingested and Datadog LLM Observability bills on span. Published starting prices are $19/mo (startup) or $49/mo and $160/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 SigNoz or Datadog LLM Observability?
SigNoz: Yes, free. Datadog LLM Observability: No or paid tier only. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.