Decision comparison
Weights & Biases is the clear choice for teams evaluating MLOps experiment tracking platforms in 2026. While Neptune.ai was a strong contender for foundation model training workflows, its acquisition by OpenAI in December 2025 means it is no longer available as an independent product. Weights & Biases offers a comprehensive feature set spanning experiment tracking, AI application evaluation, model registry, and team collaboration with transparent pricing starting from a generous free tier.
| Decision factor | Neptune.ai | Weights & Biases |
|---|---|---|
| Best For | Foundation model training at scale | Full ML lifecycle tracking and collaboration |
| Pricing Model | Contact for pricing | Free (Free tier), $60/mo (Pro), CONTACT US (Enterprise) |
| Free Tier | Not available (acquired by OpenAI) | Yes — up to 5 model seats, 5 GB/month storage |
| Open Source | No | Yes (MIT license, 11,000+ GitHub stars) |
| Deployment | Cloud-hosted | Cloud, self-hosted, and on-premise options |
Comparable public signals only; they do not establish enterprise adoption, product quality, or total cost. Product Hunt signals reflect launch engagement.
| Metric | Neptune.ai | Weights & Biases |
|---|---|---|
| PyPI weekly downloads | 31.4k | 6.6M |
As of 2026-08-10 — updated weekly.
| Feature | Neptune.ai | Weights & Biases |
|---|---|---|
| Experiment Tracking | ||
| Run logging and visualization | Yes — optimized for months-long training runs | Yes — tracks architecture, hyperparameters, git commits, model weights, GPU usage |
| Metric comparison at scale | Yes — compare thousands of metrics in seconds | Yes — compare and visualize metrics across experiments |
| Multi-step and branching support | Yes — tracks training with multiple steps and branches | Limited — standard run-based tracking |
| Collaboration and Team Features | ||
| Team collaboration | Available at enterprise level | Yes — unlimited teams on Pro plan |
| Access controls | Enterprise-level access management | Team-based access controls (Pro), custom roles (Enterprise) |
| Service accounts | Not specified | Yes — available on Pro and Enterprise plans |
| AI Application Support | ||
| AI application evaluations | Not supported | Yes — included in Free tier |
| AI application tracing | Not supported | Yes — included in Free tier |
| Registry and lineage tracking | Not specified | Yes — asset registry and lineage tracking included |
| Infrastructure and Deployment | ||
| Self-hosted deployment | Not publicly available | Yes — run locally with Docker and Python |
| HIPAA compliance | Not specified | Yes — available on Enterprise plan |
| Single Sign On (SSO) | Not specified | Yes — available on Enterprise plan |
| DevOps Integration | ||
| CI/CD automations | Not specified | Yes — included in Free tier |
| Alerts and notifications | Not specified | Yes — Slack and email alerts on Free tier |
| Audit logs | Not specified | Yes — available on Enterprise plan |
Run logging and visualization
Metric comparison at scale
Multi-step and branching support
Team collaboration
Access controls
Service accounts
AI application evaluations
AI application tracing
Registry and lineage tracking
Self-hosted deployment
HIPAA compliance
Single Sign On (SSO)
CI/CD automations
Alerts and notifications
Audit logs
Weights & Biases is the clear choice for teams evaluating MLOps experiment tracking platforms in 2026. While Neptune.ai was a strong contender for foundation model training workflows, its acquisition by OpenAI in December 2025 means it is no longer available as an independent product. Weights & Biases offers a comprehensive feature set spanning experiment tracking, AI application evaluation, model registry, and team collaboration with transparent pricing starting from a generous free tier.
Choose Weights & Biases if:
Choose Weights & Biases if you need a production-ready MLOps platform with experiment tracking, team collaboration, and flexible deployment options. Its free tier covers individual and small-team use, while Pro and Enterprise plans scale for larger organizations requiring access controls, compliance features, and dedicated support.
Choose Neptune.ai if:
Neptune.ai is no longer available as a standalone product following its acquisition by OpenAI in December 2025. If you previously used Neptune for experiment tracking, consider migrating to Weights & Biases or other MLOps alternatives such as ClearML or Comet ML.
These scenarios reflect the available product evidence. Your requirements, existing stack, and team expertise should guide the final decision.
OpenAI announced a definitive agreement to acquire Neptune.ai in December 2025. The acquisition integrates Neptune's experiment tracking tools into OpenAI's internal training stack. As a result, Neptune.ai is no longer available as a standalone commercial product for general use.
Weights & Biases offers a Free plan designed for personal development of AI applications and models at $0/mo. It includes AI application evaluations, AI application tracing, AI application scorers, AI model experiment tracking, AI assets registry & lineage tracking, and Community Support.
The Weights & Biases Pro plan starts at $60/month, billed monthly. It includes all Free tier features plus unlimited teams, team-based access controls, service accounts, and priority email and chat support. Pro is designed for early-stage teams with fewer than 50 employees.
Yes. Weights & Biases supports self-hosted deployments. You can run a W&B server locally on any machine with Docker and Python installed. The Enterprise plan adds options for single-tenant deployment with choice of region, secure private connectivity, and customer-managed encryption keys.
Neptune.ai was specifically built for monitoring months-long foundation model training runs with multiple steps and branches. However, since OpenAI acquired Neptune in December 2025, it is no longer available as a standalone product. Weights & Biases is the practical choice today, offering robust experiment tracking across the full ML lifecycle with broad framework support for PyTorch, TensorFlow, Keras, and JAX.