Claude SDK for TypeScript

The Claude SDK for TypeScript provides access to the Claude API from server-side TypeScript or JavaScript applications.

Documentation

SDK helpers (streaming, structured outputs, tool helpers and the tool runner) are documented in helpers.md. The browser and computer toolset classes have their own guides, browser-toolset.md and computer-toolset.md.

Full documentation is available at platform.claude.com/docs/en/api/sdks/typescript.

Installation

npm install @anthropic-ai/sdk

Getting started

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

const client = new Anthropic({
  apiKey: process.env['ANTHROPIC_API_KEY'], // This is the default and can be omitted
});

const message = await client.messages.create({
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Hello, Claude' }],
  model: 'claude-opus-5-5',
});

console.log(message.content);

Requirements

TypeScript >= 5.0 is supported.

The following runtimes are supported:

• Node.js 20 LTS or later (non-EOL) versions.
• Deno v1.28.0 or higher.
• 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.
• Web browsers: disabled by default to avoid exposing your secret API credentials (see API key best practices). Enable browser support by explicitly setting dangerouslyAllowBrowser to true.

Note that React Native is not supported at this time.

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

OpenTelemetry

The SDK reports each API call as an OpenTelemetry span once your application has registered a tracer provider with @opentelemetry/api, which the SDK depends on. Spans are on by default, so there is nothing to enable on the client. The openTelemetry client option selects another tracer provider, turns the spans or the trace headers off, or, with traces.contentMode: 'content', adds the content of requests and responses to them.

const client = new Anthropic({ openTelemetry: { tracerProvider } }); // a provider other than the registered one
const quiet = new Anthropic({ openTelemetry: false }); // no spans
const detailed = new Anthropic({
  openTelemetry: { traces: { contentMode: 'content', maxContentBytes: 65_536 } }, // content, up to about 64 KiB a span
});
const unpropagated = new Anthropic({ openTelemetry: { propagation: false } }); // spans, and no trace headers on the requests

await client.messages.create(params, { openTelemetry: { conversationId } }); // sets gen_ai.conversation.id

traces is a boolean, or an object with enabled, contentMode and maxContentBytes. With each request the client sends the trace context of its span, as the headers that your registered propagator writes: traceparent, and tracestate and baggage when it writes them. propagation: false sends none of them and leaves the spans as they are, for an application whose HTTP client instrumentation already propagates the trace context, so that a request does not carry it twice. A field that the option leaves unset has its default.

A client without the option reads these environment variables once, when it is constructed: ANTHROPIC_OPEN_TELEMETRY=false turns its spans off, ANTHROPIC_OPEN_TELEMETRY_PROPAGATION=false turns propagation off, and ANTHROPIC_OPEN_TELEMETRY_TRACES_CONTENT_MODE and ANTHROPIC_OPEN_TELEMETRY_TRACES_MAX_CONTENT_BYTES give contentMode and maxContentBytes. A client with the option does not read them.

client.openTelemetry is the option as the client settled it. A withOptions() copy that passes openTelemetry uses that in place of the client's whole option, so spread the settled one to change a single setting:

const { openTelemetry } = client;
const withContent = client.withOptions({
  openTelemetry: { ...openTelemetry, traces: { ...openTelemetry.traces, contentMode: 'content' } },
});

Contributing

See CONTRIBUTING.md.

License

This project is licensed under the Apache License, Version 2.0. See the LICENSE file for details. Versions released before the change from the MIT License, and third-party contributions merged before it, remain under the MIT License. See LICENSE-MIT.