Anthropic's Claude API provides access to the Claude 4.x family of models. Claude Sonnet 4.6 is ideal for most tasks; Claude Opus 4.6 handles the most complex reasoning; Claude Haiku 4.5 is fastest and most affordable. All models support extended context windows, vision inputs, tool use, and computer use. Batch API (50% off) and prompt caching (90% off cached inputs) are available.
https://api.anthropic.com/v1
Auth type
API Key Header
Auth header
x-api-key: sk-ant-api03-...
anthropic-version: 2023-06-01
Rate limit
2,000 RPM · 160,000 TPM (default)
Pricing
Pay per use
Free quota
None
Documentation
https://docs.anthropic.com
Endpoint status
Server online — HTTP 404 — server is online but path returned an error (may require auth)119ms
(checked Mar 29, 2026)
Builder score
C
64%
builder-friendly
Pass your Anthropic API key in the x-api-key header. Also include the anthropic-version header.
x-api-key: sk-ant-api03-... anthropic-version: 2023-06-01
| Plan | Price/mo | Included |
|---|---|---|
| PAYG | Free | No minimum, pay per token |
Claude Haiku 4.5: $1/M input, $5/M output. Claude Sonnet 4.6: $3/M in, $15/M out. Claude Opus 4.6: $5/M in, $25/M out. Batch API: 50% off. Prompt caching: 90% off cached inputs.
| Method | Path | Description |
|---|---|---|
| POST | /messages |
Send a message and receive a response |
| POST | /messages (streaming) |
Stream response tokens as SSE |
| GET | /models |
List available Claude models |
curl https://api.anthropic.com/v1/messages \
-H "Content-Type: application/json" \
-H "x-api-key: $ANTHROPIC_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-d '{
"model": "claude-3-5-sonnet-20241022",
"max_tokens": 1024,
"messages": [
{"role": "user", "content": "What is the capital of France?"}
]
}'
{
"id": "msg_01XFDUDYJgAACzvnptvVoYEL",
"type": "message",
"role": "assistant",
"content": [{
"type": "text",
"text": "The capital of France is Paris."
}],
"model": "claude-3-5-sonnet-20241022",
"stop_reason": "end_turn",
"usage": {
"input_tokens": 14,
"output_tokens": 10
}
}
Data sourced from API Map. Always verify pricing and rate limits against the official Anthropic documentation.