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Migrate from OpenAI

Allternit’s /v1/chat/completions endpoint is wire-compatible with OpenAI. In most cases you only need to change the base URL and API key.

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Base URL and authentication

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Chat completions

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Model mapping

Allternit exposes normalized model IDs. You can also use policy aliases and let the gateway route to the best connected model. Use GET /v1/models to list available models for your workspace.

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Feature parity notes

  • Function calling: Allternit supports tools, tool_choice, and parallel_tool_calls.
  • Streaming: Server-sent events use the same format as OpenAI.
  • JSON mode / structured outputs: Pass response_format: { "type": "json_object" } or a JSON Schema.
  • Vision: Image URLs and base64 inputs are supported.
  • Assistants API: Use Allternit Sessions and Agents for equivalent behavior.

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BYOK and self-hosted models

If you want to keep using your existing provider contracts, add an external key in the dashboard and route requests through Allternit for governance and audit.