OpenAI API (unofficial showcase)
POST/fine_tuning/jobs

Create a fine-tuning job

Creates and queues a fine-tuning job to train a model on a dataset. Supply model and training_file, and optionally configure the training method, validation data, integrations, and metadata. The job runs asynchronously; retrieve it with GET /fine_tuning/jobs/{fine_tuning_job_id} to check its status.

  • IdempotentThe SDK sends Idempotency-Key, so a retried request is only applied once.

9 body fields

Fine-tuning job configuration. model and training_file are required; the other fields are optional.

modelstringrequired
The name of the model to fine-tune. You can select one of the [supported models](https://developers.openai.com/api/docs/guides/model-optimization#fine-tuning-methods).
training_filestringrequired
The ID of an uploaded file that contains training data. See [upload file](https://developers.openai.com/api/reference/resources/files/methods/create) for how to upload a file. Your dataset must be formatted as a JSONL file. Additionally, you must upload your file with the purpose `fine-tune`. The contents of the file should differ depending on if the model uses the [chat](https://developers.openai.com/api/docs/guides/supervised-fine-tuning#formatting-your-data), [completions](https://developers.openai.com/api/docs/guides/supervised-fine-tuning#formatting-your-data) format, or if the fine-tuning method uses the [preference](https://developers.openai.com/api/docs/guides/direct-preference-optimization) format. See the [fine-tuning guide](https://developers.openai.com/api/docs/guides/model-optimization) for more details.
hyperparametersobjectdeprecatedoptional
The hyperparameters used for the fine-tuning job. This value is now deprecated in favor of `method`, and should be passed in under the `method` parameter.
suffixstringoptional
A string of up to 64 characters that will be added to your fine-tuned model name. For example, a `suffix` of "custom-model-name" would produce a model name like `ft:gpt-4o-mini:openai:custom-model-name:7p4lURel`.
Default:null
validation_filestringoptional
The ID of an uploaded file that contains validation data. If you provide this file, the data is used to generate validation metrics periodically during fine-tuning. These metrics can be viewed in the fine-tuning results file. The same data should not be present in both train and validation files. Your dataset must be formatted as a JSONL file. You must upload your file with the purpose `fine-tune`. See the [fine-tuning guide](https://developers.openai.com/api/docs/guides/model-optimization) for more details.
integrationsarrayoptional
A list of integrations to enable for your fine-tuning job.
seedintegeroptional
The seed controls the reproducibility of the job. Passing in the same seed and job parameters should produce the same results, but may differ in rare cases. If a seed is not specified, one will be generated for you.
methodobjectoptional
The method used for fine-tuning.
metadataobjectoptional
Optional set of up to 16 key-value pairs for storing structured metadata and filtering jobs.

3 status codes
200Returns the created fine-tuning job object, including its ID, base model, training file, status, and available job configuration and results.
idstringrequired
The object identifier, which can be referenced in the API endpoints.
created_atintegerrequired
The Unix timestamp (in seconds) for when the fine-tuning job was created.
errorobjectrequired
For fine-tuning jobs that have `failed`, this will contain more information on the cause of the failure.
fine_tuned_modelstringrequired
The name of the fine-tuned model that is being created. The value will be null if the fine-tuning job is still running.
finished_atintegerrequired
The Unix timestamp (in seconds) for when the fine-tuning job was finished. The value will be null if the fine-tuning job is still running.
hyperparametersobjectoptional
The hyperparameters used for the fine-tuning job. This value will only be returned when running `supervised` jobs.
modelstringrequired
The base model that is being fine-tuned.
objectstringrequired
The object type, which is always "fine_tuning.job".
Allowed:fine_tuning.job
organization_idstringrequired
The organization that owns the fine-tuning job.
result_filesarray<string>required
The compiled results file ID(s) for the fine-tuning job. You can retrieve the results with the [Files API](https://developers.openai.com/api/reference/resources/files/methods/content).
statusstringrequired
The current status of the fine-tuning job, which can be `validating_files`, `queued`, `running`, `pausing`, `paused`, `succeeded`, `failed`, or `cancelled`.
Allowed:validating_filesqueuedrunningsucceededfailedcancelledpausingpaused
trained_tokensintegerrequired
The total number of billable tokens processed by this fine-tuning job. The value will be null if the fine-tuning job is still running.
training_filestringrequired
The file ID used for training. You can retrieve the training data with the [Files API](https://developers.openai.com/api/reference/resources/files/methods/content).
validation_filestringrequired
The file ID used for validation. You can retrieve the validation results with the [Files API](https://developers.openai.com/api/reference/resources/files/methods/content).
integrationsarray<FineTuningJobIntegration>optional
A list of integrations to enable for this fine-tuning job.
seedintegerrequired
The seed used for the fine-tuning job.
estimated_finishintegeroptional
The Unix timestamp (in seconds) for when the fine-tuning job is estimated to finish. The value will be null if the fine-tuning job is not running.
methodobjectoptional
The method used for fine-tuning.
metadataobjectoptional
Set of 16 key-value pairs that can be attached to an object. This can be useful for storing additional information about the object in a structured format, and querying for objects via API or the dashboard. Keys are strings with a maximum length of 64 characters. Values are strings with a maximum length of 512 characters.
400Returned when the request is invalid or the organization does not meet the requirements to create a fine-tuning job.
errorobjectrequired
429Returned when a request or fine-tuning job limit has been exceeded.
errorobjectrequired

Error handling

A 400 is returned when the request is invalid or the organization does not meet the requirements to create a job; a 429 is returned when a request or fine-tuning job limit is exceeded. Provide both model and training_file; method.type must be supervised, dpo, or reinforcement, and seed must be between 0 and 2147483647 when supplied. The suffix must contain 1 to 64 characters, and an integration must use type wandb with a wandb.project value.