SigNoz vs W&B Weave
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.
W&B Weave
Weights & Biases' LLM tracing and evaluation product, now owned by CoreWeave after a reported $1.7B acquisition. Billed on GB of trace data ingested rather than spans or requests, which is a genuinely different cost model to everything else in the category.
| SigNoz | W&B Weave | |
|---|---|---|
| Category | Observability & Tracing | Observability & Tracing |
| Our rating | 4/5 | 4/5 |
| Starting price | $19/mo (startup) or $49/mo | Per-seat plus usage |
| Billing meter | gb-ingested | gb-ingested |
| 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 running Weights & Biases for model training and experiment tracking, who want LLM traces and evals in the same platform as their fine-tuning runs and are comfortable with usage-based ingestion billing. |
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 W&B Weave
W&B Weave is the strongest option in the category for one specific team - the one already on Weights & Biases. The lineage story is real and unmatched - a model fine-tuned in Sweeps and the eval run testing it appear in the same interface, which no AI-native competitor can offer because none of them do training. The instrumentation API is excellent, the custom scorers are plain Python, and the integration coverage is among the broadest available. Two things temper it. The billing metric is GB of trace data ingested, which is genuinely harder to forecast than per-span or per-seat pricing because it scales with prompt and context size, not just traffic. And CoreWeave now owns it following a reported $1.7B acquisition, which has come with interoperability pledges but leaves an open question about long-term direction. If you are not already a W&B customer, the bundled per-seat maths works against you and there are cheaper focused tools.
Full W&B Weave review →Frequently Asked Questions
What is the main difference between SigNoz and W&B Weave?
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. W&B Weave: Teams already running Weights & Biases for model training and experiment tracking, who want LLM traces and evals in the same platform as their fine-tuning runs and are comfortable with usage-based ingestion billing. 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 W&B Weave?
It depends entirely on your workload shape, because they meter differently - SigNoz bills on gb-ingested and W&B Weave bills on gb-ingested. Published starting prices are $19/mo (startup) or $49/mo and Per-seat plus usage 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 W&B Weave?
SigNoz: Yes, free. W&B Weave: No or paid tier only. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.