Nebius

Nebius API conversion guide - OpenAI-compatible format, parameter handling, streaming, embeddings, and special features

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

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

config.json

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

API

Refer to the API documentation for Provider Keys Management.

Go SDK

case schemas.Nebius:
    return []schemas.Key{{
        Name:   "nebius-key-1",
        Value:  *schemas.NewSecretVar("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

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"
  }'

Go SDK

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.

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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.

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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

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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.

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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)

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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.

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6. List Models

Lists available Nebius models with capabilities and context lengths.

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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

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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