Arize Phoenix vs Comet ML vs Databricks Mosaic AI vs Weights & Biases
A side-by-side look at scores, pricing and features — with RECATOOLS' ASEAN-aware verdict for each.
Arize Phoenix
Open-source LLM evaluation and observability
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Comet ML
ML experiment tracking + LLM observability
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Databricks Mosaic AI
Build and serve models next to your lakehouse data
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Weights & Biases
The near-default MLOps platform, now with CoreWeave inference
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| RECATOOLS Score | 7.8 / 10 | 7.3 / 10 | 7.3 / 10 | 8 / 10 |
| Capability | — | — | ||
| Value for money | — | — | ||
| Ease of use | — | — | ||
| ASEAN readiness | — | — | ||
| API quality | — | — | ||
| Pricing | Open Source | Freemium | Paid | Freemium |
| Free tier | — | — | 14-day trial with $400 usage credit; a no-cost 'Free Edition' also available via email signup | Free 'Basics' tier: ~5 model seats, 5GB storage, 1GB/mo Weave ingestion |
| Paid from | — | — | DBU-based, from ~$0.07-0.08/DBU for model serving | Pro from $60/mo (teams <50); usage billed for storage/Weave/inference |
| Has API | ✓ | ✓ | ✓ | ✓ |
| Open source | ✓ | ✓ | ✗ | ✗ |
| Free to use | ✓ | ✓ | ✗ | ✓ |
| Users | — | — | — | 1,400+ organizations (incl. AstraZeneca, NVIDIA) |
| Founded | 2023 | 2017 | 2013 | 2017 |
| Maker | — | — | Databricks, Inc. (from MosaicML, acquired 2023) | CoreWeave (acquired 2025) |
| Verdict | Arize Phoenix is an open-source observability and evaluation toolkit for LLM and AI applications, offering tracing, prompt and RAG debugging, evals, and OpenTelemetry-based instrumentation that runs locally or self-hoste... |
Comet ML is a well-established MLOps platform for experiment tracking, model registry, production monitoring and, increasingly, LLM evaluation/observability via its open-source Opik project. It is a credible Weights &... |
Mosaic AI's whole argument is data gravity: train, fine-tune, and serve models where your data already lives instead of exporting it to a separate AI platform. It's the generative-AI layer of the Databricks lakehouse — M... |
W&B is close to default infrastructure for ML teams — its experiment-tracking SDK is the sticky part, logging runs, metrics, and artifacts with a few lines of code. Weave extends that to LLM and agent observability w... |
| Full review → | Full review → | Full review → | Full review → |
Comparisons cover up to 4 tools. Scores are RECATOOLS editorial assessments; verify current pricing on each vendor's site.