Anthropic TypeScript API Library

This library provides convenient access to the Anthropic REST API from server-side TypeScript or JavaScript.

For the AWS Bedrock API, see @anthropic-ai/bedrock-sdk.

Migration from v0.4.x and below

In v0.5.0, we introduced a fully rewritten SDK. The new version offers better error handling, a more robust and intuitive streaming implementation, and more.

Key interface changes:

1. new Client(apiKey) → new Anthropic({ apiKey })
2. client.complete() → client.completions.create()
3. client.completeStream() → client.completions.create({ stream: true })
   1. onUpdate callback → for await (const x of stream)
   2. full message in stream → delta of message in stream

  // Import "Anthropic" instead of "Client":
- import { Client, HUMAN_PROMPT, AI_PROMPT } from '@anthropic-ai/sdk';
+ import Anthropic, { HUMAN_PROMPT, AI_PROMPT } from '@anthropic-ai/sdk';

  // Instantiate with "apiKey" as an object property:
- const client = new Client(apiKey);
+ const client = new Anthropic({ apiKey });
  // or, simply provide an ANTHROPIC_API_KEY environment variable:
+ const client = new Anthropic();

  async function main() {
    // Request & response types are the same as before, but better-typed.
    const params = {
      prompt: `${HUMAN_PROMPT} How many toes do dogs have?${AI_PROMPT}`,
      max_tokens_to_sample: 200,
      model: "claude-1",
    };

    // Instead of "client.complete()", you now call "client.completions.create()":
-   await client.complete(params);
+   await client.completions.create(params);

    // Streaming requests now use async iterators instead of callbacks:
-   client.completeStream(params, {
-     onUpdate: (completion) => {
-       console.log(completion.completion); // full text
-     },
-   });
+   const stream = await client.completions.create({ ...params, stream: true });
+   for await (const completion of stream) {
+     process.stdout.write(completion.completion); // incremental text
+   }

    // And, since this library uses `Anthropic-Version: 2023-06-01`,
    // completion streams are now incremental diffs of text
    // rather than sending the whole message every time:
    let text = '';
-   await client.completeStream(params, {
-     onUpdate: (completion) => {
-       const diff = completion.completion.replace(text, "");
-       text = completion.completion;
-       process.stdout.write(diff);
-     },
-   });
+   const stream = await client.completions.create({ ...params, stream: true });
+   for await (const completion of stream) {
+     const diff = completion.completion;
+     text += diff;
+     process.stdout.write(diff);
+   }
    console.log('Done; final text is:')
    console.log(text)
  }
  main();

The API documentation can be found here.

Installation

npm install --save @anthropic-ai/sdk
# or
yarn add @anthropic-ai/sdk

Usage

The full API of this library can be found in api.md.

import Anthropic from '@anthropic-ai/sdk';

const anthropic = new Anthropic({
  apiKey: 'my api key', // defaults to process.env["ANTHROPIC_API_KEY"]
});

async function main() {
  const completion = await anthropic.completions.create({
    model: 'claude-2',
    max_tokens_to_sample: 300,
    prompt: `${Anthropic.HUMAN_PROMPT} how does a court case get to the Supreme Court?${Anthropic.AI_PROMPT}`,
  });
}

main();

Streaming Responses

We provide support for streaming responses using Server Sent Events (SSE).

import Anthropic from '@anthropic-ai/sdk';

const anthropic = new Anthropic();

const stream = await anthropic.completions.create({
  prompt: `${Anthropic.HUMAN_PROMPT} Your prompt here${Anthropic.AI_PROMPT}`,
  model: 'claude-2',
  stream: true,
  max_tokens_to_sample: 300,
});
for await (const completion of stream) {
  console.log(completion.completion);
}

If you need to cancel a stream, you can break from the loop or call stream.controller.abort().

Request & Response types

This library includes TypeScript definitions for all request params and response fields. You may import and use them like so:

import Anthropic from '@anthropic-ai/sdk';

const anthropic = new Anthropic({
  apiKey: 'my api key', // defaults to process.env["ANTHROPIC_API_KEY"]
});

async function main() {
  const params: Anthropic.CompletionCreateParams = {
    prompt: `${Anthropic.HUMAN_PROMPT} how does a court case get to the Supreme Court?${Anthropic.AI_PROMPT}`,
    max_tokens_to_sample: 300,
    model: 'claude-2',
  };
  const completion: Anthropic.Completion = await anthropic.completions.create(params);
}

main();

Documentation for each method, request param, and response field are available in docstrings and will appear on hover in most modern editors.

Counting Tokens

We provide a separate package for counting how many tokens a given piece of text contains.

See the repository documentation for more details.

Handling errors

When the library is unable to connect to the API, or if the API returns a non-success status code (i.e., 4xx or 5xx response), a subclass of APIError will be thrown:

async function main() {
  const completion = await anthropic.completions
    .create({
      prompt: `${Anthropic.HUMAN_PROMPT} Your prompt here${Anthropic.AI_PROMPT}`,
      max_tokens_to_sample: 300,
      model: 'claude-2',
    })
    .catch((err) => {
      if (err instanceof Anthropic.APIError) {
        console.log(err.status); // 400
        console.log(err.name); // BadRequestError
        console.log(err.headers); // {server: 'nginx', ...}
      } else {
        throw err;
      }
    });
}

main();

Error codes are as followed:

Retries

Certain errors will be automatically retried 2 times by default, with a short exponential backoff. Connection errors (for example, due to a network connectivity problem), 408 Request Timeout, 409 Conflict, 429 Rate Limit, and >=500 Internal errors will all be retried by default.

You can use the maxRetries option to configure or disable this:

// Configure the default for all requests:
const anthropic = new Anthropic({
  maxRetries: 0, // default is 2
});

// Or, configure per-request:
await anthropic.completions.create(
  {
    prompt: `${Anthropic.HUMAN_PROMPT} Can you help me effectively ask for a raise at work?${Anthropic.AI_PROMPT}`,
    max_tokens_to_sample: 300,
    model: 'claude-2',
  },
  {
    maxRetries: 5,
  },
);

Timeouts

Requests time out after 10 minutes by default. You can configure this with a timeout option:

// Configure the default for all requests:
const anthropic = new Anthropic({
  timeout: 20 * 1000, // 20 seconds (default is 10 minutes)
});

// Override per-request:
await anthropic.completions.create(
  {
    prompt: `${Anthropic.HUMAN_PROMPT} Where can I get a good coffee in my neighbourhood?${Anthropic.AI_PROMPT}`,
    max_tokens_to_sample: 300,
    model: 'claude-2',
  },
  {
    timeout: 5 * 1000,
  },
);

On timeout, an APIConnectionTimeoutError is thrown.

Note that requests which time out will be retried twice by default.

Advanced Usage

Accessing raw Response data (e.g., headers)

The "raw" Response returned by fetch() can be accessed through the .asResponse() method on the APIPromise type that all methods return.

You can also use the .withResponse() method to get the raw Response along with the parsed data.

const anthropic = new Anthropic();

const response = await anthropic.completions
  .create({
    prompt: `${Anthropic.HUMAN_PROMPT} Can you help me effectively ask for a raise at work?${Anthropic.AI_PROMPT}`,
    max_tokens_to_sample: 300,
    model: 'claude-2',
  })
  .asResponse();
console.log(response.headers.get('X-My-Header'));
console.log(response.raw.statusText); // access the underlying Response object

// parses the response body, returning an object if the API responds with JSON
const completion: Completions.Completion = await response.parse();
console.log(completion.completion);

Configuring an HTTP(S) Agent (e.g., for proxies)

By default, this library uses a stable agent for all http/https requests to reuse TCP connections, eliminating many TCP & TLS handshakes and shaving around 100ms off most requests.

If you would like to disable or customize this behavior, for example to use the API behind a proxy, you can pass an httpAgent which is used for all requests (be they http or https), for example:

import http from 'http';
import Anthropic from '@anthropic-ai/sdk';
import HttpsProxyAgent from 'https-proxy-agent';

// Configure the default for all requests:
const anthropic = new Anthropic({
  httpAgent: new HttpsProxyAgent(process.env.PROXY_URL),
});

// Override per-request:
await anthropic.completions.create(
  {
    prompt: `${Anthropic.HUMAN_PROMPT} How does a court case get to the Supreme Court?${Anthropic.AI_PROMPT}`,
    max_tokens_to_sample: 300,
    model: 'claude-2',
  },
  {
    baseURL: 'http://localhost:8080/test-api',
    httpAgent: new http.Agent({ keepAlive: false }),
  },
);

Semantic Versioning

This package generally follows SemVer conventions, though certain backwards-incompatible changes may be released as minor versions:

1. Changes that only affect static types, without breaking runtime behavior.
2. Changes to library internals which are technically public but not intended or documented for external use. (Please open a GitHub issue to let us know if you are relying on such internals).
3. Changes that we do not expect to impact the vast majority of users in practice.

We take backwards-compatibility seriously and work hard to ensure you can rely on a smooth upgrade experience.

We are keen for your feedback; please open an issue with questions, bugs, or suggestions.

Requirements

TypeScript >= 4.5 is supported.

The following runtimes are supported:

• Node.js 18 LTS or later (non-EOL) versions.
• Deno v1.28.0 or higher, using import Anthropic from "npm:@anthropic-ai/sdk".
• Bun 1.0 or later.
• Cloudflare Workers.
• Vercel Edge Runtime.
• Jest 28 or greater with the "node" environment ("jsdom" is not supported at this time).
• Nitro v2.6 or greater.

Note that React Native is not supported at this time.

If you are interested in other runtime environments, please open or upvote an issue on GitHub.