Create a Text Completion

POST /v1/complete

[Legacy] Create a Text Completion.

The Text Completions API is a legacy API. We recommend using the Messages API going forward.

Future models and features will not be compatible with Text Completions. See our migration guide for guidance in migrating from Text Completions to Messages.

Headers

• "anthropic-beta": optional array of AnthropicBeta

  Optional header to specify the beta version(s) you want to use.

  • string

  • "message-batches-2024-09-24" or "prompt-caching-2024-07-31" or "computer-use-2024-10-22" or 42 more

    • "message-batches-2024-09-24"

    • "prompt-caching-2024-07-31"

    • "computer-use-2024-10-22"

    • "computer-use-2025-01-24"

    • "pdfs-2024-09-25"

    • "token-counting-2024-11-01"

    • "token-efficient-tools-2025-02-19"

    • "output-128k-2025-02-19"

    • "files-api-2025-04-14"

    • "mcp-client-2025-04-04"

    • "mcp-client-2025-11-20"

    • "dev-full-thinking-2025-05-14"

    • "interleaved-thinking-2025-05-14"

    • "code-execution-2025-05-22"

    • "extended-cache-ttl-2025-04-11"

    • "context-1m-2025-08-07"

    • "context-management-2025-06-27"

    • "model-context-window-exceeded-2025-08-26"

    • "skills-2025-10-02"

    • "fast-mode-2026-02-01"

    • "output-300k-2026-03-24"

    • "user-profiles-2026-03-24"

    • "user-profiles-2026-08-18"

    • "user-profiles-2026-09-04"

    • "advisor-tool-2026-03-01"

    • "managed-agents-2026-04-01"

    • "cache-diagnosis-2026-04-07"

    • "dreaming-2026-04-21"

    • "thinking-token-count-2026-05-13"

    • "server-side-fallback-2026-06-01"

    • "server-side-fallback-2026-07-01"

    • "fallback-credit-2026-06-01"

    • "fallback-credit-2026-07-01"

    • "agent-memory-2026-07-22"

    • "mid-conversation-tool-changes-2026-07-01"

    • "compact-2026-01-12"

    • "computer-use-2025-11-24"

    • "mcp-tunnels-2026-06-22"

    • "structured-outputs-2025-11-13"

    • "task-budgets-2026-03-13"

    • "thinking-display-updates-2026-08-18"

    • "ce-user-management-2026-07-13"

    • "mid-conversation-output-config-2026-07-01"

    • "thinking-binding-controls-2026-08-01"

    • "mid-conversation-system-clear-at-2026-08-21"

• "anthropic-workspace-id": optional string

Body parameters

• max_tokens_to_sample: number

  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.

  minimum: 1

• model: Model

  The model that will complete your prompt.

  See models for additional details and options.

  • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1"

      Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

    • "claude-mythos-5-1"

      Our most capable model for cybersecurity and biology research, available through trusted access programs

    • "claude-sonnet-5"

      High-performance model for coding and agents

    • "claude-fable-5"

      Next generation of intelligence for the hardest knowledge work and coding problems

    • "claude-mythos-5"

      Most capable model for cybersecurity and biology research

    • "claude-opus-5"

      Powerful intelligence for long-running agents and coding

    • "claude-opus-4-8"

      Powerful intelligence for long-running agents and coding

    • "claude-opus-4-7"

      Powerful intelligence for long-running agents and coding

    • "claude-mythos-preview"

      New class of intelligence, strongest in coding and cybersecurity

    • "claude-opus-4-6"

      Powerful intelligence for long-running agents and coding

    • "claude-sonnet-4-6"

      Best combination of speed and intelligence

    • "claude-haiku-4-5"

      Fastest model with near-frontier intelligence

    • "claude-haiku-4-5-20251001"

      Fastest model with near-frontier intelligence

    • "claude-opus-4-5"

      Powerful intelligence for long-running agents and coding

    • "claude-opus-4-5-20251101"

      Powerful intelligence for long-running agents and coding

    • "claude-sonnet-4-5"

      High-performance model for agents and coding

    • "claude-sonnet-4-5-20250929"

      High-performance model for agents and coding

  • string

• prompt: string

  The prompt that you want Claude to complete.

  For proper response generation you will need to format your prompt using alternating `

  Human:and

  Assistant:` conversational turns. For example:

  "
  
  Human: {userQuestion}
  
  Assistant:"

  See prompt validation and our guide to prompt design for more details.

  minLength: 1

• metadata: optional Metadata

  An object describing metadata about the request.

  • user_id: optional string or null

    An external identifier for the user who is associated with the request.

    This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

    maxLength: 512

• stop_sequences: optional array of string

  Sequences that will cause the model to stop generating.

  Our models stop on `"

  Human:"`, 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.

• stream: optional boolean

  Whether to incrementally stream the response using server-sent events.

  See streaming for details.

• temperature: optional number

  Deprecated: Deprecated. Models released after Claude Opus 4.6 do not support setting temperature. A value of 1.0 of will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

  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.

  maximum: 1, minimum: 0

• top_k: optional number

  Deprecated: Deprecated. Models released after Claude Opus 4.6 do not accept top_k; any value will be rejected with a 400 error.

  Only sample from the top K options for each subsequent token.

  Used to remove "long tail" low probability responses. Learn more technical details here.

  Recommended for advanced use cases only.

  minimum: 0

• top_p: optional number

  Deprecated: Deprecated. Models released after Claude Opus 4.6 do not support setting top_p. A value >= 0.99 will be accepted for backwards compatibility, all other values will be rejected with a 400 error.

  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.

  maximum: 1, minimum: 0

Returns

• Completion object

  • type: "completion"

    Object type.

    For Text Completions, this is always "completion".

    default: completion

  • id: string

    Unique object identifier.

    The format and length of IDs may change over time.

  • completion: string

    The resulting completion up to and excluding the stop sequences.

  • model: Model

    The model that will complete your prompt.

    See models for additional details and options.

    • "claude-fable-5-1" or "claude-mythos-5-1" or "claude-sonnet-5" or 14 more

      The model that will complete your prompt.

      See models for additional details and options.

      • "claude-fable-5-1"

        Frontier intelligence for ambitious tasks across coding, scientific discovery, and enterprise workflows

      • "claude-mythos-5-1"

        Our most capable model for cybersecurity and biology research, available through trusted access programs

      • "claude-sonnet-5"

        High-performance model for coding and agents

      • "claude-fable-5"

        Next generation of intelligence for the hardest knowledge work and coding problems

      • "claude-mythos-5"

        Most capable model for cybersecurity and biology research

      • "claude-opus-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-8"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-7"

        Powerful intelligence for long-running agents and coding

      • "claude-mythos-preview"

        New class of intelligence, strongest in coding and cybersecurity

      • "claude-opus-4-6"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-6"

        Best combination of speed and intelligence

      • "claude-haiku-4-5"

        Fastest model with near-frontier intelligence

      • "claude-haiku-4-5-20251001"

        Fastest model with near-frontier intelligence

      • "claude-opus-4-5"

        Powerful intelligence for long-running agents and coding

      • "claude-opus-4-5-20251101"

        Powerful intelligence for long-running agents and coding

      • "claude-sonnet-4-5"

        High-performance model for agents and coding

      • "claude-sonnet-4-5-20250929"

        High-performance model for agents and coding

    • string

  • stop_reason: string or null

    The reason that we stopped.

    This may be one the following values:

    • "stop_sequence": we reached a stop sequence — either provided by you via the stop_sequences parameter, or a stop sequence built into the model
    • "max_tokens": we exceeded max_tokens_to_sample or the model's maximum

Example

curl https://api.anthropic.com/v1/complete \
    -H 'Content-Type: application/json' \
    -H 'anthropic-version: 2023-06-01' \
    -H "X-Api-Key: $ANTHROPIC_API_KEY" \
    --max-time 600 \
    -d '{
          "max_tokens_to_sample": 256,
          "model": "claude-2.1",
          "prompt": "\n\nHuman: Hello, world!\n\nAssistant:",
          "temperature": 1,
          "top_k": 5,
          "top_p": 0.7
        }'

Response (200)

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