POST/completions

Create a text completion

Creates a completion from a prompt using the specified model and generation parameters. Supply model and prompt; use stream to receive partial results as server-sent events instead of a single response. The response contains generated text choices and usage statistics.

  • IdempotentThe SDK sends Idempotency-Key, so a retried request is only applied once.

18 body fields

Prompt, model, and optional text completion generation settings. model and prompt are required.

modelstringrequired
ID of the model to use. You can use the [List models](https://developers.openai.com/api/reference/resources/models/methods/list) API to see all of your available models, or see our [Model overview](https://developers.openai.com/api/docs/models) for descriptions of them.
promptstringrequired
The prompt(s) to generate completions for, encoded as a string, array of strings, array of tokens, or array of token arrays. Note that <|endoftext|> is the document separator that the model sees during training, so if a prompt is not specified the model will generate as if from the beginning of a new document.
Default:<|endoftext|>
best_ofintegeroptional
Generates `best_of` completions server-side and returns the "best" (the one with the highest log probability per token). Results cannot be streamed. When used with `n`, `best_of` controls the number of candidate completions and `n` specifies how many to return – `best_of` must be greater than `n`. **Note:** Because this parameter generates many completions, it can quickly consume your token quota. Use carefully and ensure that you have reasonable settings for `max_tokens` and `stop`.
Default:1
echobooleanoptional
Echo back the prompt in addition to the completion
Default:false
frequency_penaltynumberoptional
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://developers.openai.com/api/docs/guides/text)
Default:0
logit_biasobjectoptional
Modify the likelihood of specified tokens appearing in the completion. Accepts a JSON object that maps tokens (specified by their token ID in the GPT tokenizer) to an associated bias value from -100 to 100. You can use this [tokenizer tool](https://platform.openai.com/tokenizer?view=bpe) to convert text to token IDs. 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. As an example, you can pass `{"50256": -100}` to prevent the <|endoftext|> token from being generated.
Default:null
logprobsintegeroptional
Include the log probabilities on the `logprobs` most likely output tokens, as well the chosen tokens. For example, if `logprobs` is 5, the API will return a list of the 5 most likely tokens. The API will always return the `logprob` of the sampled token, so there may be up to `logprobs+1` elements in the response. The maximum value for `logprobs` is 5.
Default:null
max_tokensintegeroptional
The maximum number of [tokens](https://platform.openai.com/tokenizer) that can be generated in the completion. The token count of your prompt plus `max_tokens` cannot exceed the model's context length. [Example Python code](https://cookbook.openai.com/examples/how_to_count_tokens_with_tiktoken) for counting tokens.
Default:16
nintegeroptional
How many completions to generate for each prompt. **Note:** Because this parameter generates many completions, it can quickly consume your token quota. Use carefully and ensure that you have reasonable settings for `max_tokens` and `stop`.
Default:1
presence_penaltynumberoptional
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://developers.openai.com/api/docs/guides/text)
Default:0
seedintegeroptional
If specified, our 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.
stopstringoptional
Not supported with latest reasoning models `o3` and `o4-mini`. Up to 4 sequences where the API will stop generating further tokens. The returned text will not contain the stop sequence.
Default:null
streambooleanoptional
Whether to stream back partial progress. If set, 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).
Default:false
stream_optionsobjectoptional
Options for the streamed response. Set this only when `stream` is true.
suffixstringoptional
The suffix that comes after a completion of inserted text. This parameter is only supported for `gpt-3.5-turbo-instruct`.
Default:null
temperaturenumberoptional
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.
Default:1
top_pnumberoptional
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.
Default:1
userstringoptional
A unique identifier representing your end-user, which can help OpenAI to monitor and detect abuse. [Learn more](https://developers.openai.com/api/docs/guides/safety-best-practices#implement-safety-identifiers).

8 status codes
200Returns a completion object containing generated text choices, the model, creation time, and usage statistics; with streaming enabled, returns completion events as server-sent events.
idstringrequired
A unique identifier for the completion.
choicesarray<object>required
The list of completion choices the model generated for the input prompt.
createdintegerrequired
The Unix timestamp (in seconds) of when the completion was created.
modelstringrequired
The model used for completion.
system_fingerprintstringoptional
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.
objectstringrequired
The object type, which is always "text_completion"
Allowed:text_completion
usageobjectoptional
Usage statistics for the completion request.
400Returned when the completion request is invalid or request parameters are incompatible.
errorobjectrequired
401Returned when the API key is missing or revoked, or the client IP is not authorized.
errorobjectrequired
403Returned when organization policy blocks access to a personal API organization.
404Returned when the requested model is not found, unavailable, or does not support this endpoint.
errorobjectrequired
429Returned when a rate limit is exceeded.

One documented failure

  • slow_down

    Your request rate increased too quickly. Please reduce the request rate and gradually increase it again.

    Traffic increased too quickly

errorobjectrequired
500Returned when an internal error prevents the completion from being processed.
errorobjectrequired
503Returned when the service is temporarily unavailable, including when the requested model is overloaded.

One documented failure

  • server_is_overloaded

    The model is temporarily overloaded. Please retry your request after a brief delay.

    The requested model is temporarily overloaded

errorobjectrequired

Error handling

A 400 is returned when model or prompt is missing or the request parameters are invalid; a 401 indicates a missing or revoked API key or an unauthorized client IP; a 403 indicates organization policy blocks access. A 404 is returned when the model is unavailable or does not support this endpoint; a 429 indicates a rate limit was exceeded; a 500 indicates an internal error; and a 503 indicates temporary service unavailability. best_of must be between 0 and 20, n between 1 and 128, and frequency_penalty and presence_penalty between -2 and 2 when provided.