W&B Weave vs Helicone
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.
Helicone
An open-source, proxy-based LLM gateway and observability tool - now in maintenance mode after Mintlify acquired it in March 2026. Security and bug fixes only, no roadmap. Not a safe pick for new buyers.
| W&B Weave | Helicone | |
|---|---|---|
| Category | Observability & Tracing | Observability & Tracing |
| Our rating | 4/5 | 2/5 |
| Starting price | Per-seat plus usage | $79/mo |
| Billing meter | gb-ingested | request |
| Free plan | Yes | Yes |
| Free self-hosting | No or paid tier only | No or paid tier only |
| 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. | Almost nobody new - existing users who need a light open-source logging proxy and understand it's frozen. New buyers should look elsewhere. |
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 Helicone
Helicone was a clean, open-source, proxy-based observability tool - but Mintlify acquired it in March 2026 and put it in maintenance mode. Security patches, bug fixes and new-model support still ship, but there's no roadmap and Mintlify is actively helping customers migrate off. That makes it a dead end for new adopters, no matter how tidy the product is. We rate it low purely on that basis. If you're already on it, plan your exit. If you're evaluating it fresh, don't.
Full Helicone review →Frequently Asked Questions
What is the main difference between W&B Weave and Helicone?
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. Helicone: Almost nobody new - existing users who need a light open-source logging proxy and understand it's frozen. New buyers should look elsewhere. 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 Helicone?
It depends entirely on your workload shape, because they meter differently - W&B Weave bills on gb-ingested and Helicone bills on request. Published starting prices are Per-seat plus usage and $79/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 W&B Weave or Helicone?
W&B Weave: No or paid tier only. Helicone: No or paid tier only. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.