curl -X POST 'https://api.anthropic.com/v1/complete' \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H 'anthropic-version: 2023-06-01' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "example-model",
  "prompt": "example-prompt",
  "max_tokens_to_sample": 0
}'

# POST /v1/complete (Claude API)
Base URL: https://api.anthropic.com
Auth: x-api-key; Anthropic API key; required.
Status: Beta.
Request formats: application/json.
Last verified: 2026-10-20

> Create a Text Completion

## Critical Gotchas
* Authentication uses the `x-api-key` header and requests also require an `anthropic-version` header.
* The official OpenAPI URL is discovered from the SDK repository manifest and must remain under Anthropic's trusted Stainless storage prefix.

## cURL
curl -X POST 'https://api.anthropic.com/v1/complete' \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H 'anthropic-version: 2023-06-01' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "example-model",
  "prompt": "example-prompt",
  "max_tokens_to_sample": 0
}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| model | body | string | Yes | The model that will complete your prompt.  See [models](https://docs.anthropi... |
| prompt | body | string | Yes | The prompt that you want Claude to complete.  For proper response generation... |
| max_tokens_to_sample | body | integer | Yes | The maximum number of tokens to generate before stopping.  Note that our mode... |
| stop_sequences | body | string[] | No | Sequences that will cause the model to stop generating.  Our models stop on `... |
| temperature | body | number | No | Amount of randomness injected into the response.  Defaults to `1.0`. Ranges f... |
| top_p | body | number | No | Use nucleus sampling.  In nucleus sampling, we compute the cumulative distrib... |
| top_k | body | integer | No | Only sample from the top K options for each subsequent token.  Used to remove... |
| metadata | body | object | No | Request body field metadata. |
Other params: stream

## Response example
{"completion":" Hello! My name is Claude.","id":"compl_018CKm6gsux7P8yMcwZbeCPw"}

---
Need an API key? Get one at https://console.anthropic.com/settings/keys

POST

POST /v1/complete — Claude API

Beta

Anthropic API key (required); https://api.anthropic.com

Claude API

Create a Text Completion

Base URL: https://api.anthropic.com
Auth: x-api-key: <ANTHROPIC_API_KEY>
Last verified: 2026-10-20 · upstream hash matched

Actions Try in browser→

Agents: curl -H "Accept: text/markdown" this URL
→ 398 tokens · Vary: Accept

Critical gotchas

Authentication uses the x-api-key header and requests also require an anthropic-version header.

The official OpenAPI URL is discovered from the SDK repository manifest and must remain under Anthropic's trusted Stainless storage prefix.

cURL

curl -X POST 'https://api.anthropic.com/v1/complete' \  -H "x-api-key: $ANTHROPIC_API_KEY" \  -H 'anthropic-version: 2023-06-01' \  -H 'Content-Type: application/json' \  -d '{  "model": "example-model",  "prompt": "example-prompt",  "max_tokens_to_sample": 0}'

Parameters

Name	In	Type	Required	Description
model	body	string	Yes	The model that will complete your prompt. See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.
prompt	body	string	Yes	The prompt that you want Claude to complete. For proper response generation you will need to format your prompt using alternating `\n\nHuman:` and `\n\nAssistant:` conversational turns. For example: ``` "\n\nHuman: {userQuestion}\n\nAssistant:" ``` See [prompt validation](https://platform.claude.com/docs/en/build-with-claude/working-with-messages) and our guide to [prompt design](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/overview) for more details.
max_tokens_to_sample	body	integer	Yes	The maximum number of tokens to generate before stopping. Note that our models may stop _before_ reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate.
stop_sequences	body	string[]	No	Sequences that will cause the model to stop generating. Our models stop on `"\n\nHuman:"`, and may include additional built-in stop sequences in the future. By providing the stop_sequences parameter, you may include additional strings that will cause the model to stop generating.
temperature	body	number	No	Amount of randomness injected into the response. Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0` for analytical / multiple choice, and closer to `1.0` for creative and generative tasks. Note that even with `temperature` of `0.0`, the results will not be fully deterministic.
top_p	body	number	No	Use nucleus sampling. In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by `top_p`. Recommended for advanced use cases only.
top_k	body	integer	No	Only sample from the top K options for each subsequent token. Used to remove "long tail" low probability responses. [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277). Recommended for advanced use cases only.
metadata	body	object	No	Request body field metadata.
stream	body	boolean	No	Whether to incrementally stream the response using server-sent events. See [streaming](https://platform.claude.com/docs/en/build-with-claude/streaming) for details.

Response 200 OK

{
  "completion": " Hello! My name is Claude.",
  "id": "compl_018CKm6gsux7P8yMcwZbeCPw",
  "model": "claude-2.1",
  "stop_reason": "stop_sequence",
  "type": "completion"
}

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