W&B Weave vs Traceloop
Both are observability & tracing tools. Here is how they actually differ on price, billing model and deployment.
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.
Traceloop
The company behind OpenLLMetry, acquired by ServiceNow in March 2026 to power AI Control Tower. The Apache-2.0 SDK is safe and still actively developed - the managed platform's standalone future is the open question.
| W&B Weave | Traceloop | |
|---|---|---|
| Category | Observability & Tracing | Observability & Tracing |
| Our rating | 4/5 | 3/5 |
| Starting price | Per-seat plus usage | Custom |
| Billing meter | gb-ingested | span |
| Free plan | Yes | Yes |
| Free self-hosting | No or paid tier only | Yes, free |
| Best for | 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. | Teams that want vendor-neutral OpenTelemetry LLM instrumentation via OpenLLMetry, which is genuinely safe to adopt. The managed platform suits existing ServiceNow customers, or teams needing air-gapped deployment who can get contractual clarity on the roadmap. |
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 →Our verdict on Traceloop
Split this decision in two, because the SDK and the platform now carry very different risk. OpenLLMetry - the Apache-2.0 OpenTelemetry extension - is one of the safest things you can adopt in this category. It is permissively licensed, the team publicly committed it stays that way, it exports to 25+ backends including Datadog, and it remained actively maintained through the acquisition. You can instrument with it and never create a Traceloop account. The managed platform is a different question. ServiceNow acquired Traceloop in March 2026, reportedly for $60 to $80 million, and shipped the integration into AI Control Tower at Knowledge 2026 in May. The stated strategic purpose is enterprise AI governance inside ServiceNow, not an independent observability product. The site still promotes signups and nothing suggests a Helicone-style wind-down, but a standalone product whose parent bought it for a different purpose is a roadmap you do not control. Use the SDK freely. Get contractual clarity before you build on the platform.
Full Traceloop review →Frequently Asked Questions
What is the main difference between W&B Weave and Traceloop?
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. Traceloop: Teams that want vendor-neutral OpenTelemetry LLM instrumentation via OpenLLMetry, which is genuinely safe to adopt. The managed platform suits existing ServiceNow customers, or teams needing air-gapped deployment who can get contractual clarity on the roadmap. Both sit in Observability & Tracing, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, W&B Weave or Traceloop?
It depends entirely on your workload shape, because they meter differently - W&B Weave bills on gb-ingested and Traceloop bills on span. Published starting prices are Per-seat plus usage and Custom 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 W&B Weave or Traceloop?
W&B Weave: No or paid tier only. Traceloop: Yes, free. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.