API reference

Neptune Service Shutdown - March 5, 2026

Following its acquisition by OpenAI, Neptune services will be permanently discontinued.
All remaining data will be deleted at shutdown and cannot be recovered.

See timelines, export instructions, and migration guides in the Transition Hub.

•  Run

  ---

  Work with runs individually or in bulk.

  • neptune.init_run()
  • neptune.init_project()
  • Project.fetch_runs_table()
  • del run["namespace"]

•  management

  ---

  Manage your workspace and users.

  • invite_to_workspace()
  • create_project()
  • trash_objects()
  • clear_trash()

•  Field types

  ---

  A field is a location where metadata is logged. The field type determines the available methods and display options.

  • Artifact
  • File
  • FileSeries
  • FloatSeries
  • more →

•  Environment variables

  ---

  Use environment variables to make your setup more smooth and secure.

  • NEPTUNE_API_TOKEN
  • NEPTUNE_PROJECT
  • NEPTUNE_CUSTOM_RUN_ID
  • NEPTUNE_MODE
  • NEPTUNE_DATA_DIRECTORY
  • more →

•  Connection modes

  ---

  Set the logging and synchronization mode.

  • async (default)
  • debug
  • offline
  • read-only
  • sync

•  CLI

  ---

  You can use the Neptune Command Line Interface to manage and sync locally stored metadata.

  • neptune clear
  • neptune status
  • neptune sync

Browse the complete list of functions, parameters, and constants in the index →

Integrations

API references for Neptune integrations with other ML frameworks:

• Apache Airflow
• Catalyst
• Detectron2
• fastai
• Transformers
• Kedro
• Keras
• LightGBM
• Lightning
• MLflow
• Optuna
• Prophet
• PyTorch
• PyTorch Ignite
• Sacred
• scikit-learn
• skorch
• TensorBoard
• XGBoost

Errors, warnings, and other messages

For error help pages, expand the Erros and messages section in the left nav.

Other errors:

• Out of range float values are not JSON compliant → Downgrade simplejson to 3.18
• Connection pool is full, discarding connection: app.neptune.ai → Non-issue unrelated to Neptune.¹

See also

• NQL (Neptune Query Language) – used to construct complex queries when fetching runs.
• System namespace (sys) – contains the name, description, tags, creation time, and other auto-logged metadata.
• Change the location of the .neptune folder – see how to move the directory or access it from elsewhere in your system.
• Set up a Neptune error handling function
• Help ≫ Debugging options

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1. The error is shown by urllib3 to indicate that a connection is dropped after a request is completed. It doesn't imply data loss. For details, see StackOverflow . ↩