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Create Completion (Legacy)

POST /v1/completions
This is a compatibility endpoint, not the primary recommended path. For new integrations, prefer /v1/chat/completions or /v1/responses.

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Current Production Status

As of March 23, 2026, Crazyrouter production confirms:
  • the route still exists
  • a request using the classic example model gpt-3.5-turbo-instruct returned 503
  • the error code was model_not_found
  • the message said the model was temporarily unavailable
In practice, this means the endpoint should be treated as legacy-client compatibility only, not as the default path for new work.

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Current Recommendation

  1. Use Chat Completions for new chat-style integrations
  2. Use Responses when you need GPT-5 reasoning, web search, or newer response shapes
  3. Only keep testing /v1/completions if you already depend on a legacy client and have confirmed that your legacy model is currently available

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Retest Template

If you must verify whether a legacy model still works on this endpoint, first confirm the model ID through /v1/models, then send a minimal request: 
curl https://crazyrouter.com/v1/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "YOUR_LEGACY_MODEL",
    "prompt": "Say hello in three words.",
    "max_tokens": 16
  }'
Observed production error example: 
{
  "error": {
    "code": "model_not_found",
    "message": "Model gpt-3.5-turbo-instruct is temporarily unavailable",
    "type": "new_api_error"
  }
}