Fine-Tuning API Reference

Create a Fine-Tuning Job

POST /jobs

Create a new fine-tuning job to train a model on your dataset.

Request Parameters

Parameter	Type	Required	Description
model	string	Yes	Base model to fine-tune (e.g., `gpt-4.1`).
training_file	string	Yes	File ID for the training data.
validation_file	string	No	Optional file ID for validation data
`hyperparameters`	object	Deprecated in the OpenAI API, use `method` instead	Custom hyperparameters for training
`suffix`	string	No	Custom suffix for the resulting model name
`method`	object	No	Fine-tuning method configuration
`seed`	integer	No	Random seed for reproducibility
`integrations`	array	No	List of integrations for tracking
`metadata`	object	No	Additional metadata for the job

Example Request

 curl /v1/fine_tuning/jobs \
  -H "api-key: $API_KEY" \
  -d '{
    "training_file": "file-BK7bzQj3FfZFXr7DbL6xJwfo",
    "model": "gpt-4o"
  }'

Example Response

{
  "object": "fine_tuning.job",
  "id": "ftjob-abc123",
  "model": "gpt-4o-2024-07-18",
  "created_at": 1721764800,
  "fine_tuned_model": null,
  "organization_id": "org-123",
  "result_files": [],
  "status": "queued",
  "validation_file": null,
  "training_file": "file-abc123",
  "method": {
    "type": "supervised",
    "supervised": {
      "hyperparameters": {
        "batch_size": "auto",
        "learning_rate_multiplier": "auto",
        "n_epochs": "auto",
      }
    }
  },
  "metadata": null
}

Retrieve Fine-Tuning Job

GET /jobs/{job_id}

Get information about a specific fine-tuning job.

Path Parameters

Parameter	Type	Required	Description
job_id	string	Yes	The ID of the fine-tuning job.

Example Request

curl /v1/fine_tuning/jobs/ft-AF1WoRqd3aJAHsqc9NY7iL8F \
  -H "api-key: "

Example Response

{
  "object": "fine_tuning.job",
  "id": "ftjob-abc123",
  "model": "davinci-002",
  "created_at": 1692661014,
  "finished_at": 1692661190,
  "fine_tuned_model": "ft:davinci-002:my-org:custom_suffix:7q8mpxmy",
  "organization_id": "org-123",
  "result_files": [
      "file-abc123"
  ],
  "status": "succeeded",
  "validation_file": null,
  "training_file": "file-abc123",
  "hyperparameters": {
      "n_epochs": 4,
      "batch_size": 1,
      "learning_rate_multiplier": 1.0
  },
  "trained_tokens": 5768,
  "integrations": [],
  "seed": 0,
  "estimated_finish": 0,
  "method": {
    "type": "supervised",
    "supervised": {
      "hyperparameters": {
        "n_epochs": 4,
        "batch_size": 1,
        "learning_rate_multiplier": 1.0
      }
    }
  }
}

List Fine-Tuning Jobs

GET /jobs

Gets a list of fine-tuning jobs for the current user.

Request Parameters

Parameter	Type	Default	Description
limit	integer	20	Number of jobs to return.
after	string	null	Pagination cursor.

Example Request

curl /v1/fine_tuning/jobs?limit=2&metadata[key]=value \
  -H "api-key: "

Example Response

{
  "object": "list",
  "data": [
    {
      "object": "fine_tuning.job",
      "id": "ftjob-abc123",
      "model": "gpt-4o-2024-07-18",
      "created_at": 1721764800,
      "fine_tuned_model": null,
      "organization_id": "org-123",
      "result_files": [],
      "status": "queued",
      "validation_file": null,
      "training_file": "file-abc123",
      "metadata": {
        "key": "value"
      }
    },
    { ... },
    { ... }
  ], "has_more": true
}

List Fine-Tuning Events

GET /jobs/{job_id}/events

Get a list of events for a fine-tuning job.

Path Parameters

Parameter	Type	Default	Default
job_id	string	Yes	The ID of the fine-tuning job.

Request Parameters

Parameter	Type	Default	Default
limit	integer	20	Number of events to return.
after	string	null	Pagination cursor.

Example Request

curl /v1/fine_tuning/jobs/ftjob-abc123/events \
  -H "api-key: "

Example Response

{
  "object": "list",
  "data": [
    {
      "object": "fine_tuning.job.event",
      "id": "ft-event-ddTJfwuMVpfLXseO0Am0Gqjm",
      "created_at": 1721764800,
      "level": "info",
      "message": "Fine tuning job successfully completed",
      "data": null,
      "type": "message"
    },
    {
      "object": "fine_tuning.job.event",
      "id": "ft-event-tyiGuB72evQncpH87xe505Sv",
      "created_at": 1721764800,
      "level": "info",
      "message": "New fine-tuned model created: ft:gpt-4o:openai::7p4lURel",
      "data": null,
      "type": "message"
    }
  ],
  "has_more": true
}

List Job Checkpoints

GET /jobs/{job_id}/checkpoints

Retrieves all checkpoints for a fine‑tuning job.

Path Parameters

Parameter	Type	Default	Default
job_id	string	Yes	The ID of the fine-tuning job.

Request Parameters

Parameter	Type	Default	Default
limit	integer	20	Number of events to return.
after	string	null	Pagination cursor.

Example Request

 curl /v1/fine_tuning/jobs/ftjob-abc123/checkpoints \
  -H "api-key: $API_KEY"

Example Response

{
  "object": "list",
  "data": [
    {
      "object": "fine_tuning.job.checkpoint",
      "id": "ftckpt_zc4Q7MP6XxulcVzj4MZdwsAB",
      "created_at": 1721764867,
      "fine_tuned_model_checkpoint": "ft:gpt-4o-2024-07-18:my-org:custom-suffix:96olL566:ckpt-step-2000",
      "metrics": {
        "full_valid_loss": 0.134,
        "full_valid_mean_token_accuracy": 0.874
      },
      "fine_tuning_job_id": "ftjob-abc123",
      "step_number": 2000
    },
    {
      "object": "fine_tuning.job.checkpoint",
      "id": "ftckpt_enQCFmOTGj3syEpYVhBRLTSy",
      "created_at": 1721764800,
      "fine_tuned_model_checkpoint": "ft:gpt-4o-2024-07-18:my-org:custom-suffix:7q8mpxmy:ckpt-step-1000",
      "metrics": {
        "full_valid_loss": 0.167,
        "full_valid_mean_token_accuracy": 0.781
      },
      "fine_tuning_job_id": "ftjob-abc123",
      "step_number": 1000
    }
  ],
  "first_id": "ftckpt_zc4Q7MP6XxulcVzj4MZdwsAB",
  "last_id": "ftckpt_enQCFmOTGj3syEpYVhBRLTSy",
  "has_more": true
}

Cancel a Fine-Tuning Job

POST /jobs/{job_id}/cancel

Cancels a fine-tuning job that is in progress.

Path Parameters

Parameter	Type	Default	Default
job_id	string	Yes	The ID of the fine-tuning job.

Example Request

 curl -X POST /v1/fine_tuning/jobs/ftjob-abc123/cancel \
  -H "api-key: $API_KEY"

Example Response

 {
  "object": "fine_tuning.job",
  "id": "ftjob-abc123",
  "model": "gpt-4o-2024-07-18",
  "created_at": 1721764800,
  "fine_tuned_model": null,
  "organization_id": "org-123",
  "result_files": [],
  "status": "cancelled",
  "validation_file": "file-abc123",
  "training_file": "file-abc123"
}

Delete a fine-tuning job

DELETE /jobs/{job_id}

Deletes a fine-tuning job and its associated files.

Path Parameters

Parameter	Type	Default	Default
job_id	string	Yes	The ID of the fine-tuning job.

Example Request

 curl -X DELETE /v1/fine_tuning/jobs/ftjob-abc123 \
  -H "api-key: $API_KEY"

Response

Returns a 204 No Content response on success.