Anthropic Claude API

Anthropic Claude API provides Claude 3.5 Sonnet / Claude 3 Opus large language models — known for alignment safety and long context (200K tokens).

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Use it when

200K context (one of industry's longest — fits entire books)

Watch for

Not cheap (Sonnet $3/$15 per M tokens)

First check

Create API key at console.anthropic.com. POST https://api.anthropic.com/v1/messages with model: "claude-3-5-sonnet-20241022" + messages.

Auth

api_key

CORS

HTTPS

Yes

Signup

Latency

288 ms

Protocol

REST

Pricing

paid

Uptime · 30-day window

Probes: 1Uptime: 100%Avg latency: 288ms

About this API

Anthropic is an AI safety company founded 2021 by former OpenAI research lead Dario Amodei and sister Daniela, positioning itself as "more aligned, more honest" LLM alternative to OpenAI. Latest flagship: Claude 3.5 Sonnet (mid-tier, cost-effective, top-tier coding) and Claude 3 Opus (high-tier, complex reasoning). Two standout features: (1) 200K tokens ultra-long context — longer than GPT-4o's 128K, can fit an entire book or large codebase for QA in one call; (2) Constitutional AI training makes Claude more "compliant" — rarely generates inappropriate content, low hallucination rate. Claude 3.5 Sonnet is current SOTA on SWE-bench (real software engineering tasks), default in Cursor, Aider, and other code agent tools. API similar to OpenAI but has own schema (system is separate field outside messages array).

What you can build

1Enterprise chatbots (high compliance requirements)
2Long document analysis (fit 200K tokens in one call)
3Code generation (Claude 3.5 SOTA in coding)
4Content generation + safety review
5AI agents / tool use

Strengths & limitations

Strengths

200K context (one of industry's longest — fits entire books)
Strict alignment training (rarely hallucinates or goes out of bounds)
Top-tier coding in LLMs (claude-3-5-sonnet is current SWE-bench SOTA)

Limitations

Not cheap (Sonnet $3/$15 per M tokens)
Restricted access in some regions (parts of Europe and Asia)
Less rich ecosystem than OpenAI

Example request

Generic template — replace <endpoint> with the real path from the docs.

curl https://www.anthropic.com/<endpoint> \
  -H "Authorization: Bearer $API_KEY"
# Some providers use X-Api-Key instead — verify in the docs.

Getting started

Create API key at console.anthropic.com. POST https://api.anthropic.com/v1/messages with model: "claude-3-5-sonnet-20241022" + messages.

FAQ

Claude vs. GPT-4?+

Long docs / coding / alignment-sensitive → Claude. Mature ecosystem/function calling / slightly lower price → GPT-4.

Does Anthropic accept mainland China accounts?+

No direct service to mainland China. Accessible via AWS Bedrock or Google Vertex AI as intermediary.

Technical details

CORS: ?HTTPS: YesSignup: ?Open source: No

Auth type: api_key
Pricing: paid
Rate limit: tier 1 5 RPM；高 tier 4000 RPM
Protocols: REST
SDKs: python, typescript, go, java, ruby
Response time: 288 ms
Last health check: 5/12/2026, 7:36:35 AM