Overview

Nebius is an OpenAI-compatible provider offering comprehensive API support. Bifrost delegates to the OpenAI implementation with standard parameter filtering. Key features:

Full OpenAI compatibility - Chat, text completion, embeddings, and responses
Streaming support - Server-Sent Events with delta-based updates
AI Project ID - Nebius-specific project identifier support
Tool calling - Complete function definition and execution
Parameter filtering - Removes unsupported OpenAI-specific fields

Supported Operations

Operation	Non-Streaming	Streaming	Endpoint
Chat Completions	✅	✅	`/v1/chat/completions`
Responses API	✅	✅	`/v1/chat/completions`
Text Completions	✅	✅	`/v1/completions`
Embeddings	✅	-	`/v1/embeddings`
Image Generation	✅	-	`/v1/images/generations`
List Models	✅	-	`/v1/models`
Speech (TTS)	❌	❌	-
Transcriptions (STT)	❌	❌	-
Files	❌	❌	-
Batch	❌	❌	-

Unsupported Operations (❌): Speech, Transcriptions, Files, and Batch are not supported by the upstream Nebius API. These return UnsupportedOperationError.

Setup & Configuration

Configure Nebius as a provider.

Web UI
config.json
API
Go SDK

Navigate to Models > Model Providers. Look for Nebius under Configured Providers. If it is missing, click on Add New Provider and select Nebius.
Click Add Key or edit an existing key.
Set a name for your key.
Paste your API key directly or use an environment variable (for example, env.NEBIUS_API_KEY).
Set Allowed Models to All Models (default) or the specific model allowlist you want this key to serve.
Save the provider configuration.

{
  "providers": {
    "nebius": {
      "keys": [
        {
          "name": "nebius-key-1",
          "value": "env.NEBIUS_API_KEY",
          "models": [
            "*"
          ],
          "weight": 1.0
        }
      ]
    }
  }
}

curl --location 'http://localhost:8080/api/providers' \
--header 'Content-Type: application/json' \
--data '{
  "provider": "nebius",
  "keys": [
    {
      "name": "nebius-key-1",
      "value": "env.NEBIUS_API_KEY",
      "models": [
        "*"
      ],
      "weight": 1.0
    }
  ]
}'

case schemas.Nebius:
    return []schemas.Key{{
        Name:   "nebius-key-1",
        Value:  *schemas.NewEnvVar("env.NEBIUS_API_KEY"),
        Models: []string{"*"},
        Weight: 1.0,
    }}, nil

1. Chat Completions

Request Parameters

Nebius supports all standard OpenAI chat completion parameters. For full parameter reference and behavior, see OpenAI Chat Completions.

Nebius-Specific Parameters

ai_project_id (Optional): Nebius allows specifying a project ID for resource organization:

Gateway
Go SDK

curl -X POST http://localhost:8080/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nebius/model-name",
    "messages": [...],
    "ai_project_id": "project-123"
  }'

request := &schemas.BifrostChatRequest{
    Model: "model-name",
    Input: messages,
    Params: &schemas.ChatParameters{
        ExtraParams: map[string]interface{}{
            "ai_project_id": "project-123",
        },
    },
}

The ai_project_id is appended as a query parameter to the request URL.

Filtered Parameters

Removed for Nebius compatibility:

prompt_cache_key - Not supported
verbosity - Anthropic-specific
store - Not supported
service_tier - Not supported

Nebius supports all standard OpenAI message types, tools, responses, and streaming formats. For details on message handling, tool conversion, responses, and streaming, refer to OpenAI Chat Completions.

2. Responses API

Converted internally to Chat Completions:

ResponsesRequest → ChatRequest → ChatCompletion → ResponsesResponse

Same parameter support and message handling as Chat Completions. Supports ai_project_id via extra_params.

3. Text Completions

Nebius supports legacy text completion format:

Parameter	Mapping
`prompt`	Direct pass-through
`max_tokens`	max_tokens
`temperature`, `top_p`	Direct pass-through
`stop`	Stop sequences
`frequency_penalty`, `presence_penalty`	Penalty parameters

4. Embeddings

Nebius supports text embeddings:

Parameter	Notes
`input`	Text or array of texts
`model`	Embedding model name
`encoding_format`	”float” or “base64”
`dimensions`	Custom output dimensions (optional)

Response returns embedding vectors with usage information.

5. Image Generation

Request Parameters

Parameter	Type	Required	Notes
`model`	string	✅	Model identifier
`prompt`	string	✅	Text description of the image to generate
`size`	string	❌	Image size in WxH format (e.g., `"1024x1024"`). Converted to separate `width` and `height` integers
`output_format`	string	❌	Output format: `"png"`, `"jpeg"`, `"webp"`. Note: `"jpeg"` is converted to `"jpg"`
`response_format`	string	❌	Response format: `"url"` or `"b64_json"`
`seed`	int	❌	Seed for reproducible generation
`negative_prompt`	string	❌	Negative prompt
`num_inference_steps`	int	❌	Number of inference steps
`extra_params`	object	❌	Nebius-specific parameters (see below)

Extra Parameters (via extra_params)

Parameter	Type	Notes
`guidance_scale`	int	Guidance scale (0-100)
`ai_project_id`	string	Nebius project ID (added as query parameter)

Request Conversion

Model & Prompt: bifrostReq.Model → req.Model (pointer), bifrostReq.Input.Prompt → req.Prompt (pointer)
Size Conversion: params.size (WxH format like "1024x1024") is split into:
- width: Integer extracted from first part (e.g., 1024)
- height: Integer extracted from second part (e.g., 1024)
Output Format:
- params.output_format → req.ResponseExtension
- Special conversion: "jpeg" → "jpg" (Nebius uses "jpg" not "jpeg")
Response Format: params.response_format → req.ResponseFormat (passed directly: "url" or "b64_json")
Seed & Negative Prompt: params.seed → req.Seed, params.negative_prompt → req.NegativePrompt (passed directly)
Num Inference Steps: params.num_inference_steps → req.NumInferenceSteps (passed directly)
Extra Parameters:
- guidance_scale → req.GuidanceScale (int pointer)
- ai_project_id → Added as query parameter ?ai_project_id={value} to the request URL

Response Conversion

Image Data: Each item in response.data[] → ImageData with:
- url: From data[].url
- b64_json: From data[].b64_json
- revised_prompt: From data[].revised_prompt
- index: Sequential index (0, 1, 2, …)
ID: response.id → response.ID
Provider: Set to nebius in ExtraFields

Endpoint: /v1/images/generations Streaming: Image generation streaming is not supported by Nebius.

6. List Models

Lists available Nebius models with capabilities and context lengths.

Unsupported Features

Feature	Reason
Speech/TTS	Not offered by Nebius API
Transcription/STT	Not offered by Nebius API
Batch Operations	Not offered by Nebius API
File Management	Not offered by Nebius API

Caveats

Cache Control Stripped

Severity: Medium Behavior: Cache control directives are removed from messages Impact: Prompt caching features don’t work Code: Stripped during JSON marshaling

Parameter Filtering

Severity: Low Behavior: OpenAI-specific fields filtered out Impact: prompt_cache_key, verbosity, store removed Code: filterOpenAISpecificParameters

User Field Size Limit

Severity: Low Behavior: User field > 64 characters silently dropped Impact: Longer user identifiers are lost Code: SanitizeUserField enforces 64-char max

​Overview

​Supported Operations

​Setup & Configuration

​1. Chat Completions

​Request Parameters

​Nebius-Specific Parameters

​Filtered Parameters

​2. Responses API

​3. Text Completions

​4. Embeddings

​5. Image Generation

​6. List Models

​Unsupported Features

​Caveats

Overview

Supported Operations

Setup & Configuration

1. Chat Completions

Request Parameters

Nebius-Specific Parameters

Filtered Parameters

2. Responses API

3. Text Completions

4. Embeddings

5. Image Generation

6. List Models

Unsupported Features

Caveats