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Machine Learning · head to head

Neptune.ai vs OpenAI API

Neptune.ai logo

Neptune.ai

Machine Learning

Metadata store for MLOps

From
Free
Rated
-
OpenAI API logo

OpenAI API

Machine Learning

Hosted API for OpenAI's language, embedding, image and audio models, billed per token

From
$0.15/per-million-tokens
Rated
-

The short version

  • Only Neptune.ai has a free tier, so it costs nothing to try first.
  • Each has a real cost: Neptune.ai free tier limited to 100 hours per month, exhausted quickly with serious ML work; OpenAI API cost scales with tokens rather than with seats, so a successful feature's bill grows with its adoption, and an interface that lets users paste long documents has no natural ceiling on spend unless you build one yourself.
  • They diverge on capability: Neptune.ai covers Experiment tracking, OpenAI API covers Text and reasoning models.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Neptune.ai and OpenAI API actually diverge.

Attributes where Neptune.ai and OpenAI API differ
AttributeNeptune.aiOpenAI API
Starting priceFree$0.15/per-million-tokens
Pricing modelUnknownusage-based
Free tierYesNo
PlatformsWeb, Self-hostedApi
Founded20172015

Identical on both: user rating (Not yet rated), category (Machine Learning).

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 Neptune.ai

  • Experiment tracking
  • Model registry
  • Metadata logging
  • Comparison views
  • Custom dashboards
  • PyTorch
  • TensorFlow
  • Keras

Only in OpenAI API

  • Text and reasoning models
  • Embeddings
  • Speech and audio
  • Image generation
  • Function calling
  • Structured outputs
  • Batch processing
  • Prompt caching

What people use each for

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

Neptune.ai

  • Machine learningnot OpenAI API
  • Data analysisnot OpenAI API
  • Model trainingnot OpenAI API
  • Predictive analyticsnot OpenAI API

OpenAI API

  • Adding summarisation, drafting or classification to an existing product where building a model would take longer than the product's whole roadmapnot Neptune.ai
  • Retrieval-augmented question answering over internal documents, using the embedding and generation models togethernot Neptune.ai
  • Extracting structured records from unstructured text, where schema-constrained output removes most of the parsing problemnot Neptune.ai
  • Prototyping a language feature quickly to find out whether it is worth the cost of a self-hosted alternative laternot Neptune.ai

Where each one falls short

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

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

OpenAI API

  • Cost scales with tokens rather than with seats, so a successful feature's bill grows with its adoption, and an interface that lets users paste long documents has no natural ceiling on spend unless you build one yourself.
  • Models are deprecated on the vendor's timetable, and a fine-tuned model built on a retired base goes with it, so the tuning work and the data curation behind it must be redone rather than migrated.
  • Behaviour shifts between model versions in ways no test catches unless you wrote one, so prompts tuned over months against a particular snapshot can regress quietly on migration, which makes an evaluation suite a prerequisite rather than an improvement.
  • It cannot run inside your own network, so data residency requirements, air-gapped environments and contracts forbidding third-party processing rule it out regardless of the provider's own security posture.
  • You inherit its availability and its rate limits, so a provider incident is an outage in your product and a traffic spike can be throttled at precisely the moment the feature is proving itself.

Pricing, plan by plan

Neptune.ai

Free

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

OpenAI API

$0.15/per-million-tokens
  • GPT-4o mini$0.15/per-million-input-tokens
    • Fast
    • Affordable
  • GPT-4o$5/per-million-input-tokens
    • Multimodal
    • 128K context

Which should you pick?

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.

Choose OpenAI API if

  • You need text and reasoning models.
  • You work on Api.
  • You also want embeddings.

Questions people ask

Is Neptune.ai or OpenAI API better?
Neither clearly leads. Neptune.ai starts at Free and OpenAI API at $0.15/per-million-tokens, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Neptune.ai or OpenAI API?
Neptune.ai has a free tier; the other does not. Paid plans start at Free for Neptune.ai and $0.15/per-million-tokens for OpenAI API.
Does Neptune.ai or OpenAI API run on more platforms?
Neptune.ai runs on Web, Self-hosted. OpenAI API runs on Api.
Can I use Neptune.ai for free?
Yes. Neptune.ai has a free tier, so you can try it without paying. OpenAI API starts at $0.15/per-million-tokens.
What is Neptune.ai best used for?
Neptune.ai is most often used for machine learning, data analysis, model training, predictive analytics. Of those, machine learning and data analysis are not what OpenAI API is typically brought in for.
What can Neptune.ai do that OpenAI API cannot?
Neptune.ai covers Experiment tracking, Model registry, Metadata logging, Comparison views. OpenAI API covers Text and reasoning models, Embeddings, Speech and audio, Image generation.

Answered from the vendors’ own pages

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
OpenAI API: Is my data used to train the models?

API inputs and outputs are not used for training by default, which differs from the consumer product. Retention periods and enterprise terms change, so read the current data usage policy rather than trusting a summary.

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
OpenAI API: Can I run these models on my own hardware?

No. The weights are not distributed. If self-hosting is a requirement, you are looking at open-weight models instead, with the operational and quality trade-offs that implies.

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
OpenAI API: How is it priced?

Per token, with input and output priced differently and each model priced differently. Batch processing and cached input prefixes reduce it. The practical consequence is that your bill is a function of prompt design, not just of request count.

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
OpenAI API: What is the difference from Azure OpenAI Service?

The same model family delivered by Microsoft under an Azure contract, with Azure identity, networking and regional controls, and a different release cadence for new models. Enterprises with an Azure agreement often choose it for procurement and data residency reasons rather than technical ones.

OpenAI API: How do I keep the cost under control?

Cap input length, cache repeated prefixes, route easy requests to smaller models, use the batch path where latency does not matter, and set per-user limits before launch rather than after the first surprising invoice.

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