OpenAI Chat completion

https://api.ajan.io/openai/{region}/v1/chat/completions

from openai import OpenAI
client = OpenAI(
  base_url="https://api.ajan.io/openai/eu/v1",
  api_key="<YOUR_AJAN_API_KEY>"
)

completion = client.chat.completions.create(
  model="gpt-5-mini",
  messages=[
    {"role": "user", "content": "Write a short poem about cats."}
  ]
)

print(completion.choices[0].message.content)

import { streamText } from "ai";
import { createOpenAI } from "@ai-sdk/openai";

const ajanProvider = createOpenAI({
  baseURL: "https://api.ajan.io/openai/eu/v1",
  apiKey: "<YOUR_AJAN_API_KEY>",
});

const result = await streamText({
  model: ajanProvider("gpt-5-mini"),
  prompt: "Write a short poem about cats",
});

for await (const textPart of result.textStream) {
  process.stdout.write(textPart);
}

openapi: 3.0.0
info:
  title: ajan API
  version: 3.0.0
servers:
  - url: https://api.ajan.io
    description: Production
security:
  - bearerAuth: []
paths:
  /openai/{region}/v1/chat/completions:
    post:
      tags:
        - Chat
      summary: Creates a model response for the given chat conversation.
      parameters:
        - name: region
          in: path
          required: true
          description: The region of the API to use.
          schema:
            type: string
            enum:
              - eu
              - us
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateChatCompletionRequest'
            example:
              model: gpt-4o-mini
              messages:
                - role: system
                  content: You are a helpful agent.
                - role: user
                  content: Write a short poem about cats.
      responses:
        '200':
          description: OK
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CreateChatCompletionResponse'
              example:
                choices:
                  - message:
                      content: |-
                        In moonlit shadows soft they prowl,
                        With eyes aglow in night's dark cowl.
                      role: assistant
                    index: 0
                    finish_reason: stop
                    logprobs: null
                created: 1721722200
                id: chatcmpl-8o4sq3sSzGVqS0aQyjlXuuEGVZnSj
                model: gpt-4o-2024-05-13
                object: chat.completion
                system_fingerprint: fp_asd28019bf
                usage:
                  completion_tokens: 34
                  prompt_tokens: 14
                  total_tokens: 48
      security:
        - bearerAuth: []
components:
  schemas:
    CreateChatCompletionRequest:
      type: object
      properties:
        messages:
          description: >-
            A list of messages comprising the conversation so far. [Example
            Python
            code](https://cookbook.openai.com/examples/how_to_format_inputs_to_chatgpt_models).
          type: array
          minItems: 1
          items:
            $ref: '#/components/schemas/ChatCompletionRequestMessage'
        model:
          description: >-
            ID of the model to use. See the [model endpoint
            compatibility](https://platform.openai.com/docs/models/model-endpoint-compatibility)
            table for details on which models work with the Chat API.
          example: gpt-4-turbo
          anyOf:
            - type: string
            - type: string
              enum:
                - gpt-4o
                - gpt-4o-mini
                - gpt-4
                - gpt-3.5-turbo
          x-oaiTypeLabel: string
        frequency_penalty:
          type: number
          default: 0
          minimum: -2
          maximum: 2
          nullable: true
          description: >
            Number between -2.0 and 2.0. Positive values penalize new tokens
            based on their existing frequency in the text so far, decreasing the
            model's likelihood to repeat the same line verbatim.

            [See more information about frequency and presence
            penalties.](https://platform.openai.com/docs/guides/text-generation/parameter-details)
        logit_bias:
          type: object
          x-oaiTypeLabel: map
          default: null
          nullable: true
          additionalProperties:
            type: integer
          description: >
            Modify the likelihood of specified tokens appearing in the
            completion.

            Accepts a JSON object that maps tokens (specified by their token ID
            in the tokenizer) to an associated bias value from -100 to 100.
            Mathematically, the bias is added to the logits generated by the
            model prior to sampling. The exact effect will vary per model, but
            values between -1 and 1 should decrease or increase likelihood of
            selection; values like -100 or 100 should result in a ban or
            exclusive selection of the relevant token.
        logprobs:
          description: >-
            Whether to return log probabilities of the output tokens or not. If
            true, returns the log probabilities of each output token returned in
            the `content` of `message`.
          type: boolean
          default: false
          nullable: true
        top_logprobs:
          description: >-
            An integer between 0 and 20 specifying the number of most likely
            tokens to return at each token position, each with an associated log
            probability. `logprobs` must be set to `true` if this parameter is
            used.
          type: integer
          minimum: 0
          maximum: 20
          nullable: true
        max_tokens:
          description: >
            The maximum number of tokens that can be generated in the chat
            completion.

            The total length of input tokens and generated tokens is limited by
            the model's context length. [Example Python
            code](https://cookbook.openai.com/examples/how_to_count_tokens_with_tiktoken)
            for counting tokens.
          type: integer
          nullable: true
        presence_penalty:
          type: number
          default: 0
          minimum: -2
          maximum: 2
          nullable: true
          description: >
            Number between -2.0 and 2.0. Positive values penalize new tokens
            based on whether they appear in the text so far, increasing the
            model's likelihood to talk about new topics.

            [See more information about frequency and presence
            penalties.](https://platform.openai.com/docs/guides/text-generation/parameter-details)
        response_format:
          type: object
          description: >
            An object specifying the format that the model must output.
            Compatible with GPT-4 Turbo and all GPT-3.5 Turbo models newer than
            `gpt-3.5-turbo-1106`.

            Setting to `{ "type": "json_object" }` enables JSON mode, which
            guarantees the message the model generates is valid JSON.

            **Important:** when using JSON mode, you **must** also instruct the
            model to produce JSON yourself via a system or user message. Without
            this, the model may generate an unending stream of whitespace until
            the generation reaches the token limit, resulting in a long-running
            and seemingly "stuck" request. Also note that the message content
            may be partially cut off if `finish_reason="length"`, which
            indicates the generation exceeded `max_tokens` or the conversation
            exceeded the max context length.
          properties:
            type:
              type: string
              enum:
                - text
                - json_object
              example: json_object
              default: text
              description: Must be one of `text` or `json_object`.
        seed:
          type: integer
          minimum: -9223372036854776000
          maximum: 9223372036854776000
          nullable: true
          description: >
            This feature is in Beta.

            If specified, OpenAI's system will make a best effort to sample
            deterministically, such that repeated requests with the same `seed`
            and parameters should return the same result.

            Determinism is not guaranteed, and you should refer to the
            `system_fingerprint` response parameter to monitor changes in the
            backend.
          x-oaiMeta:
            beta: true
        stop:
          description: |
            Up to 4 sequences where the API will stop generating further tokens.
          default: null
          oneOf:
            - type: string
              nullable: true
            - type: array
              minItems: 1
              maxItems: 4
              items:
                type: string
        stream:
          description: >
            If set, partial message deltas will be sent, like in ChatGPT. Tokens
            will be sent as data-only [server-sent
            events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#Event_stream_format)
            as they become available, with the stream terminated by a `data:
            [DONE]` message. [Example Python
            code](https://cookbook.openai.com/examples/how_to_stream_completions).
          type: boolean
          nullable: true
          default: false
        temperature:
          type: number
          minimum: 0
          maximum: 2
          default: 1
          example: 1
          nullable: true
          description: >
            What sampling temperature to use, between 0 and 2. Higher values
            like 0.8 will make the output more random, while lower values like
            0.2 will make it more focused and deterministic.

            We generally recommend altering this or `top_p` but not both.
        top_p:
          type: number
          minimum: 0
          maximum: 1
          default: 1
          example: 1
          nullable: true
          description: >
            An alternative to sampling with temperature, called nucleus
            sampling, where the model considers the results of the tokens with
            top_p probability mass. So 0.1 means only the tokens comprising the
            top 10% probability mass are considered.

            We generally recommend altering this or `temperature` but not both.
        tools:
          type: array
          description: >
            A list of tools the model may call. Currently, only functions are
            supported as a tool. Use this to provide a list of functions the
            model may generate JSON inputs for. A max of 128 functions are
            supported.
          items:
            $ref: '#/components/schemas/ChatCompletionTool'
        tool_choice:
          $ref: '#/components/schemas/ChatCompletionToolChoiceOption'
        reasoning_effort:
          type: string
          nullable: true
          description: >
            Constrains how much effort the model spends on reasoning before
            responding. Lower values produce faster, cheaper responses; higher
            values produce more thorough reasoning. Supported values are `none`,
            `minimal`, `low`, `medium`, `high`, and `xhigh`. Not all values are
            supported by all models.
          enum:
            - none
            - minimal
            - low
            - medium
            - high
            - xhigh
        user:
          type: string
          example: user-1234
          description: >
            A unique identifier representing your end-user, which can help
            OpenAI to monitor and detect abuse. [Learn
            more](https://platform.openai.com/docs/guides/safety-best-practices/end-user-ids).
        function_call:
          deprecated: true
          description: >
            Deprecated in favor of `tool_choice`.

            Controls which (if any) function is called by the model.

            `none` means the model will not call a function and instead
            generates a message.

            `auto` means the model can pick between generating a message or
            calling a function.

            Specifying a particular function via `{"name": "my_function"}`
            forces the model to call that function.

            `none` is the default when no functions are present. `auto` is the
            default if functions are present.
          oneOf:
            - type: string
              description: >
                `none` means the model will not call a function and instead
                generates a message. `auto` means the model can pick between
                generating a message or calling a function.
              enum:
                - none
                - auto
            - $ref: '#/components/schemas/ChatCompletionFunctionCallOption'
          x-oaiExpandable: true
        functions:
          deprecated: true
          description: |
            Deprecated in favor of `tools`.

            A list of functions the model may generate JSON inputs for.
          type: array
          minItems: 1
          maxItems: 128
          items:
            $ref: '#/components/schemas/ChatCompletionFunctions'
      required:
        - model
        - messages
    CreateChatCompletionResponse:
      type: object
      description: >-
        Represents a chat completion response returned by model, based on the
        provided input.
      properties:
        id:
          type: string
          description: A unique identifier for the chat completion.
        choices:
          type: array
          description: >-
            A list of chat completion choices. Can be more than one if `n` is
            greater than 1.
          items:
            type: object
            required:
              - finish_reason
              - index
              - message
              - logprobs
            properties:
              finish_reason:
                type: string
                description: >
                  The reason the model stopped generating tokens. This will be
                  `stop` if the model hit a natural stop point or a provided
                  stop sequence,

                  `length` if the maximum number of tokens specified in the
                  request was reached,

                  `content_filter` if content was omitted due to a flag from
                  OpenAI's content filters,

                  `tool_calls` if the model called a tool, or `function_call`
                  (deprecated) if the model called a function.
                enum:
                  - stop
                  - length
                  - tool_calls
                  - content_filter
                  - function_call
              index:
                type: integer
                description: The index of the choice in the list of choices.
              message:
                $ref: '#/components/schemas/ChatCompletionResponseMessage'
              logprobs:
                description: Log probability information for the choice.
                type: object
                nullable: true
                properties:
                  content:
                    description: >-
                      A list of message content tokens with log probability
                      information.
                    type: array
                    items:
                      $ref: '#/components/schemas/ChatCompletionTokenLogprob'
                    nullable: true
                required:
                  - content
        created:
          type: integer
          description: >-
            The Unix timestamp (in seconds) of when the chat completion was
            created.
        model:
          type: string
          description: The model used for the chat completion.
        system_fingerprint:
          type: string
          description: >
            This fingerprint represents the backend configuration that the model
            runs with.

            Can be used in conjunction with the `seed` request parameter to
            understand when backend changes have been made that might impact
            determinism.
        object:
          type: string
          description: The object type, which is always `chat.completion`.
          enum:
            - chat.completion
        usage:
          $ref: '#/components/schemas/CompletionUsage'
      required:
        - choices
        - created
        - id
        - model
        - object
      x-oaiMeta:
        name: The chat completion object
        group: chat
        example: |
          {
            "id": "chatcmpl-123",
            "object": "chat.completion",
            "created": 1677652288,
            "model": "gpt-4o-mini",
            "system_fingerprint": "fp_44709d6fcb",
            "choices": [{
              "index": 0,
              "message": {
                "role": "assistant",
                "content": "\n\nHello there, how may I assist you today?",
              },
              "logprobs": null,
              "finish_reason": "stop"
            }],
            "usage": {
              "prompt_tokens": 9,
              "completion_tokens": 12,
              "total_tokens": 21
            }
    ChatCompletionRequestMessage:
      oneOf:
        - $ref: '#/components/schemas/ChatCompletionRequestSystemMessage'
        - $ref: '#/components/schemas/ChatCompletionRequestUserMessage'
        - $ref: '#/components/schemas/ChatCompletionRequestAssistantMessage'
        - $ref: '#/components/schemas/ChatCompletionRequestToolMessage'
        - $ref: '#/components/schemas/ChatCompletionRequestFunctionMessage'
      x-oaiExpandable: true
    ChatCompletionTool:
      type: object
      properties:
        type:
          type: string
          enum:
            - function
          description: The type of the tool. Currently, only `function` is supported.
        function:
          $ref: '#/components/schemas/FunctionObject'
      required:
        - type
        - function
    ChatCompletionToolChoiceOption:
      description: >
        Controls which (if any) tool is called by the model.

        `none` means the model will not call any tool and instead generates a
        message.

        `auto` means the model can pick between generating a message or calling
        one or more tools.

        `required` means the model must call one or more tools.

        Specifying a particular tool via `{"type": "function", "function":
        {"name": "my_function"}}` forces the model to call that tool.

        `none` is the default when no tools are present. `auto` is the default
        if tools are present.
      oneOf:
        - type: string
          description: >
            `none` means the model will not call any tool and instead generates
            a message. `auto` means the model can pick between generating a
            message or calling one or more tools. `required` means the model
            must call one or more tools.
          enum:
            - none
            - auto
            - required
        - $ref: '#/components/schemas/ChatCompletionNamedToolChoice'
      x-oaiExpandable: true
    ChatCompletionFunctionCallOption:
      type: object
      description: >
        Specifying a particular function via `{"name": "my_function"}` forces
        the model to call that function.
      properties:
        name:
          type: string
          description: The name of the function to call.
      required:
        - name
    ChatCompletionFunctions:
      type: object
      deprecated: true
      properties:
        description:
          type: string
          description: >-
            A description of what the function does, used by the model to choose
            when and how to call the function.
        name:
          type: string
          description: >-
            The name of the function to be called. Must be a-z, A-Z, 0-9, or
            contain underscores and dashes, with a maximum length of 64.
        parameters:
          $ref: '#/components/schemas/FunctionParameters'
      required:
        - name
    ChatCompletionResponseMessage:
      type: object
      description: A chat completion message generated by the model.
      properties:
        content:
          type: string
          description: The contents of the message.
          nullable: true
        tool_calls:
          $ref: '#/components/schemas/ChatCompletionMessageToolCalls'
        role:
          type: string
          enum:
            - assistant
          description: The role of the author of this message.
        function_call:
          type: object
          deprecated: true
          description: >-
            Deprecated and replaced by `tool_calls`. The name and arguments of a
            function that should be called, as generated by the model.
          properties:
            arguments:
              type: string
              description: >-
                The arguments to call the function with, as generated by the
                model in JSON format. Note that the model does not always
                generate valid JSON, and may hallucinate parameters not defined
                by your function schema. Validate the arguments in your code
                before calling your function.
            name:
              type: string
              description: The name of the function to call.
          required:
            - name
            - arguments
      required:
        - role
        - content
    ChatCompletionTokenLogprob:
      type: object
      properties:
        token:
          description: The token.
          type: string
        logprob:
          description: >-
            The log probability of this token, if it is within the top 20 most
            likely tokens. Otherwise, the value `-9999.0` is used to signify
            that the token is very unlikely.
          type: number
        bytes:
          description: >-
            A list of integers representing the UTF-8 bytes representation of
            the token. Useful in instances where characters are represented by
            multiple tokens and their byte representations must be combined to
            generate the correct text representation. Can be `null` if there is
            no bytes representation for the token.
          type: array
          items:
            type: integer
          nullable: true
        top_logprobs:
          description: >-
            List of the most likely tokens and their log probability, at this
            token position. In rare cases, there may be fewer than the number of
            requested `top_logprobs` returned.
          type: array
          items:
            type: object
            properties:
              token:
                description: The token.
                type: string
              logprob:
                description: >-
                  The log probability of this token, if it is within the top 20
                  most likely tokens. Otherwise, the value `-9999.0` is used to
                  signify that the token is very unlikely.
                type: number
              bytes:
                description: >-
                  A list of integers representing the UTF-8 bytes representation
                  of the token. Useful in instances where characters are
                  represented by multiple tokens and their byte representations
                  must be combined to generate the correct text representation.
                  Can be `null` if there is no bytes representation for the
                  token.
                type: array
                items:
                  type: integer
                nullable: true
            required:
              - token
              - logprob
              - bytes
      required:
        - token
        - logprob
        - bytes
        - top_logprobs
    CompletionUsage:
      type: object
      description: Usage statistics for the completion request.
      properties:
        completion_tokens:
          type: integer
          description: Number of tokens in the generated completion.
        prompt_tokens:
          type: integer
          description: Number of tokens in the prompt.
        prompt_tokens_details:
          type: object
          description: Breakdown of tokens used in the prompt.
          properties:
            cached_tokens:
              type: integer
              description: Number of prompt tokens served from the provider's prompt cache.
              example: 0
          additionalProperties: true
        total_tokens:
          type: integer
          description: Total number of tokens used in the request (prompt + completion).
      required:
        - prompt_tokens
        - completion_tokens
        - total_tokens
    ChatCompletionRequestSystemMessage:
      type: object
      title: System message
      properties:
        content:
          description: The contents of the system message.
          type: string
        role:
          type: string
          enum:
            - system
          description: The role of the messages author, in this case `system`.
        name:
          type: string
          description: >-
            An optional name for the participant. Provides the model information
            to differentiate between participants of the same role.
      required:
        - content
        - role
    ChatCompletionRequestUserMessage:
      type: object
      title: User message
      properties:
        content:
          description: |
            The contents of the user message.
          oneOf:
            - type: string
              description: The text contents of the message.
              title: Text content
            - type: array
              description: >-
                An array of content parts with a defined type, each can be of
                type `text` or `image_url` when passing in images. You can pass
                multiple images by adding multiple `image_url` content parts.
                Image input is only supported when using the
                `gpt-4-visual-preview` model.
              title: Array of content parts
              items:
                $ref: '#/components/schemas/ChatCompletionRequestMessageContentPart'
              minItems: 1
          x-oaiExpandable: true
        role:
          type: string
          enum:
            - user
          description: The role of the messages author, in this case `user`.
        name:
          type: string
          description: >-
            An optional name for the participant. Provides the model information
            to differentiate between participants of the same role.
      required:
        - content
        - role
    ChatCompletionRequestAssistantMessage:
      type: object
      title: Assistant message
      properties:
        content:
          nullable: true
          type: string
          description: >
            The contents of the assistant message. Required unless `tool_calls`
            or `function_call` is specified.
        role:
          type: string
          enum:
            - assistant
          description: The role of the messages author, in this case `assistant`.
        name:
          type: string
          description: >-
            An optional name for the participant. Provides the model information
            to differentiate between participants of the same role.
        tool_calls:
          $ref: '#/components/schemas/ChatCompletionMessageToolCalls'
        function_call:
          type: object
          deprecated: true
          description: >-
            Deprecated and replaced by `tool_calls`. The name and arguments of a
            function that should be called, as generated by the model.
          nullable: true
          properties:
            arguments:
              type: string
              description: >-
                The arguments to call the function with, as generated by the
                model in JSON format. Note that the model does not always
                generate valid JSON, and may hallucinate parameters not defined
                by your function schema. Validate the arguments in your code
                before calling your function.
            name:
              type: string
              description: The name of the function to call.
          required:
            - arguments
            - name
      required:
        - role
    ChatCompletionRequestToolMessage:
      type: object
      title: Tool message
      properties:
        role:
          type: string
          enum:
            - tool
          description: The role of the messages author, in this case `tool`.
        content:
          type: string
          description: The contents of the tool message.
        tool_call_id:
          type: string
          description: Tool call that this message is responding to.
      required:
        - role
        - content
        - tool_call_id
    ChatCompletionRequestFunctionMessage:
      type: object
      title: Function message
      deprecated: true
      properties:
        role:
          type: string
          enum:
            - function
          description: The role of the messages author, in this case `function`.
        content:
          nullable: true
          type: string
          description: The contents of the function message.
        name:
          type: string
          description: The name of the function to call.
      required:
        - role
        - content
        - name
    FunctionObject:
      type: object
      properties:
        description:
          type: string
          description: >-
            A description of what the function does, used by the model to choose
            when and how to call the function.
        name:
          type: string
          description: >-
            The name of the function to be called. Must be a-z, A-Z, 0-9, or
            contain underscores and dashes, with a maximum length of 64.
        parameters:
          $ref: '#/components/schemas/FunctionParameters'
      required:
        - name
    ChatCompletionNamedToolChoice:
      type: object
      description: >-
        Specifies a tool the model should use. Use to force the model to call a
        specific function.
      properties:
        type:
          type: string
          enum:
            - function
          description: The type of the tool. Currently, only `function` is supported.
        function:
          type: object
          properties:
            name:
              type: string
              description: The name of the function to call.
          required:
            - name
      required:
        - type
        - function
    FunctionParameters:
      type: object
      description: >-
        The parameters the functions accepts, described as a JSON Schema object.
        See the
        [guide](https://platform.openai.com/docs/guides/function-calling) for
        examples, and the [JSON Schema
        reference](https://json-schema.org/understanding-json-schema/reference)
        for documentation about the format. 

        Omitting `parameters` defines a function with an empty parameter list.
      additionalProperties: true
    ChatCompletionMessageToolCalls:
      type: array
      description: The tool calls generated by the model, such as function calls.
      items:
        $ref: '#/components/schemas/ChatCompletionMessageToolCall'
    ChatCompletionRequestMessageContentPart:
      oneOf:
        - $ref: '#/components/schemas/ChatCompletionRequestMessageContentPartText'
        - $ref: '#/components/schemas/ChatCompletionRequestMessageContentPartImage'
      x-oaiExpandable: true
    ChatCompletionMessageToolCall:
      type: object
      properties:
        id:
          type: string
          description: The ID of the tool call.
        type:
          type: string
          enum:
            - function
          description: The type of the tool. Currently, only `function` is supported.
        function:
          type: object
          description: The function that the model called.
          properties:
            name:
              type: string
              description: The name of the function to call.
            arguments:
              type: string
              description: >-
                The arguments to call the function with, as generated by the
                model in JSON format. Note that the model does not always
                generate valid JSON, and may hallucinate parameters not defined
                by your function schema. Validate the arguments in your code
                before calling your function.
          required:
            - name
            - arguments
      required:
        - id
        - type
        - function
    ChatCompletionRequestMessageContentPartText:
      type: object
      title: Text content part
      properties:
        type:
          type: string
          enum:
            - text
          description: The type of the content part.
        text:
          type: string
          description: The text content.
      required:
        - type
        - text
    ChatCompletionRequestMessageContentPartImage:
      type: object
      title: Image content part
      properties:
        type:
          type: string
          enum:
            - image_url
          description: The type of the content part.
        image_url:
          type: object
          properties:
            url:
              type: string
              description: Either a URL of the image or the base64 encoded image data.
              format: uri
            detail:
              type: string
              description: >-
                Specifies the detail level of the image. Learn more in the
                [Vision
                guide](https://platform.openai.com/docs/guides/vision/low-or-high-fidelity-image-understanding).
              enum:
                - auto
                - low
                - high
              default: auto
          required:
            - url
      required:
        - type
        - image_url
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API Key
      description: API key as Bearer token. Format "Bearer YOUR_API_KEY"