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AI · head to head

Arize AI vs Neptune.ai

Arize AI logo

Arize AI

AI

AI engineering platform for observability and evaluation of agents and LLM apps

From
Free
Free plan
Yes
Full reviewWebsite
Neptune.ai logo

Neptune.ai

Machine Learning

Metadata store for MLOps

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Arize AI the free plan caps trace spans at 25,000 per month with only 15 days of retention.; Neptune.ai free tier limited to 100 hours per month, exhausted quickly with serious ML work
  • They diverge on capability: Arize AI covers End-to-end tracing, Neptune.ai covers Experiment tracking.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Arize AI and Neptune.ai actually diverge.

Attributes where Arize AI and Neptune.ai differ
AttributeArize AINeptune.ai
Pricing modelfreemiumUnknown
Platformsweb, apiWeb, Self-hosted
CategoryAIMachine Learning
FoundedUnknown2017

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Arize AI

  • End-to-end tracing
  • Evaluation framework
  • Prompt testing and improvement
  • Alyx AI engineering agent
  • Data warehouse integrations

Only in Neptune.ai

  • Experiment tracking
  • Model registry
  • Metadata logging
  • Comparison views
  • PyTorch
  • TensorFlow
  • Keras
  • scikit-learn

Both cover

  • Custom dashboards

What people use each for

The jobs each tool is most often brought in to do.

Arize AI

  • Tracing and debugging production AI agentsnot Neptune.ai
  • Running large-scale evaluations across traces and sessionsnot Neptune.ai
  • Improving prompts before production rolloutnot Neptune.ai
  • Storing and querying GenAI traces alongside a data warehousenot Neptune.ai

Neptune.ai

  • Machine learningnot Arize AI
  • Data analysisnot Arize AI
  • Model trainingnot Arize AI
  • Predictive analyticsnot Arize AI

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Arize AI

  • The free plan caps trace spans at 25,000 per month with only 15 days of retention.
  • Self-hosted deployment and Data Fabric integration are restricted to the custom-priced Enterprise tier.
  • Pricing beyond the $50/month Pro plan requires a custom quote, making cost planning less transparent at scale.
  • Advanced compliance features like HIPAA are only available on Enterprise.

Neptune.ai

  • Free tier limited to 100 hours per month, exhausted quickly with serious ML work
  • Lacks hyperparameter sweeps compared to Weights and Biases
  • No pipeline orchestration or broader MLOps lifecycle management
  • Dashboard visualization limitations - automatic resizing affects visualization order and size
  • Cloud-based SaaS only (as of last available service) requires internet connectivity

Pricing, plan by plan

Arize AI

Free
  • AX FreeFree
    • 25k trace spans/month
    • 1 GB storage/month
    • 15-day retention
  • AX Pro$50/month
    • 50k trace spans/month
    • 10 GB storage/month
    • 30-day retention
  • AX Enterprise$undefined/mo
    • Custom trace spans, storage, and retention
    • SaaS or self-hosted deployment
    • Managed agents and Data Fabric

Neptune.ai

Free

No published plan breakdown. See the Neptune.ai review.

Which should you pick?

Choose Arize AI if

  • You need end-to-end tracing.
  • You want to start without paying.
  • You work on web, api.
  • You also want evaluation framework.
Arize AI review

Choose Neptune.ai if

  • You need experiment tracking.
  • You want to start without paying.
  • You work on Web, Self-hosted.
  • You also want model registry.
Neptune.ai review

Questions people ask

Is Arize AI or Neptune.ai better?
Neither clearly leads. Arize AI starts at Free and Neptune.ai at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Arize AI or Neptune.ai?
Arize AI starts at Free and Neptune.ai at Free.
Does Arize AI or Neptune.ai run on more platforms?
Arize AI runs on web, api. Neptune.ai runs on Web, Self-hosted.
Can I use Arize AI for free?
Both have a free tier, so you can try either at no cost before committing.
What is Arize AI best used for?
Arize AI is most often used for tracing and debugging production ai agents, running large-scale evaluations across traces and sessions, improving prompts before production rollout, storing and querying genai traces alongside a data warehouse. Of those, tracing and debugging production ai agents and running large-scale evaluations across traces and sessions are not what Neptune.ai is typically brought in for.
What can Arize AI do that Neptune.ai cannot?
Arize AI covers End-to-end tracing, Evaluation framework, Prompt testing and improvement, Alyx AI engineering agent. Neptune.ai covers Experiment tracking, Model registry, Metadata logging, Comparison views. Both handle Custom dashboards.

Answered from the vendors’ own pages

Arize AI: What does Arize AX cost?

Arize AX offers a free plan, a Pro plan at $50/month, and a custom-priced Enterprise plan, with pricing based on trace spans, storage, and retention needs.

Source
Neptune.ai: Does Neptune.ai support self-hosting?

Yes. Neptune can be self-hosted on a Kubernetes cluster with ClickHouse, MySQL, and Redis dependencies, allowing organizations to maintain full data control.

Source
Arize AI: Is there a free plan, and what are its limits?

The AX Free plan includes 25,000 trace spans and 1 GB of storage per month with 15-day retention, plus unlimited users, evaluations, and experiments.

Source
Neptune.ai: What machine learning frameworks does Neptune integrate with?

Neptune integrates with PyTorch, TensorFlow, Keras, scikit-learn, XGBoost, LightGBM, Hugging Face Transformers, and Optuna for hyperparameter optimization.

Source
Arize AI: What deployment options are available?

Free and Pro plans are SaaS-only, while Enterprise customers can choose SaaS or self-hosted deployment with custom SLAs.

Source
Neptune.ai: What is the cost for a team of 10 data scientists?

Neptune's Team plan costs $49 per user per month, resulting in $490/month for 10 users, comparable to Weights and Biases at $50/user.

Source
Neptune.ai: When is Neptune.ai shutting down?

Neptune.ai is shutting down its external SaaS service on March 5, 2026, following its acquisition by OpenAI in December 2025. Customers must export and migrate data before that date.

Source
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