5.6 KiB
Claude API — cURL / Raw HTTP
Use these examples when the user needs raw HTTP requests or is working in a language without an official SDK.
Setup
```bash export ANTHROPIC_API_KEY="your-api-key" ```
Basic Message Request
```bash curl https://api.anthropic.com/v1/messages \ -H "Content-Type: application/json" \ -H "x-api-key: $ANTHROPIC_API_KEY" \ -H "anthropic-version: 2023-06-01" \ -d '{ "model": "{{OPUS_ID}}", "max_tokens": 1024, "messages": [ {"role": "user", "content": "What is the capital of France?"} ] }' ```
Parsing the response
Use `jq` to extract fields from the JSON response. Do not use `grep`/`sed` — JSON strings can contain any character and regex parsing will break on quotes, escapes, or multi-line content.
```bash
Capture the response, then extract fields
response=$(curl -s https://api.anthropic.com/v1/messages \ -H "Content-Type: application/json" \ -H "x-api-key: $ANTHROPIC_API_KEY" \ -H "anthropic-version: 2023-06-01" \ -d '{"model":"{{OPUS_ID}}","max_tokens":1024,"messages":[{"role":"user","content":"Hello"}]}')
Print the first text block (-r strips the JSON quotes)
echo "$response" | jq -r '.content[0].text'
Read usage fields
input_tokens=$(echo "$response" | jq -r '.usage.input_tokens') output_tokens=$(echo "$response" | jq -r '.usage.output_tokens')
Read stop reason (for tool-use loops)
stop_reason=$(echo "$response" | jq -r '.stop_reason')
Extract all text blocks (content is an array; filter to type=="text")
echo "$response" | jq -r '.content[] | select(.type == "text") | .text' ```
Streaming (SSE)
```bash 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": "{{OPUS_ID}}", "max_tokens": 1024, "stream": true, "messages": [{"role": "user", "content": "Write a haiku"}] }' ```
The response is a stream of Server-Sent Events:
``` event: message_start data: {"type":"message_start","message":{"id":"msg_...","type":"message",...}}
event: content_block_start data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}
event: content_block_delta data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Hello"}}
event: content_block_stop data: {"type":"content_block_stop","index":0}
event: message_delta data: {"type":"message_delta","delta":{"stop_reason":"end_turn"},"usage":{"output_tokens":12}}
event: message_stop data: {"type":"message_stop"} ```
Tool Use
```bash 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": "{{OPUS_ID}}", "max_tokens": 1024, "tools": [{ "name": "get_weather", "description": "Get current weather for a location", "input_schema": { "type": "object", "properties": { "location": {"type": "string", "description": "City name"} }, "required": ["location"] } }], "messages": [{"role": "user", "content": "What is the weather in Paris?"}] }' ```
When Claude responds with a `tool_use` block, send the result back:
```bash 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": "{{OPUS_ID}}", "max_tokens": 1024, "tools": [{ "name": "get_weather", "description": "Get current weather for a location", "input_schema": { "type": "object", "properties": { "location": {"type": "string", "description": "City name"} }, "required": ["location"] } }], "messages": [ {"role": "user", "content": "What is the weather in Paris?"}, {"role": "assistant", "content": [ {"type": "text", "text": "Let me check the weather."}, {"type": "tool_use", "id": "toolu_abc123", "name": "get_weather", "input": {"location": "Paris"}} ]}, {"role": "user", "content": [ {"type": "tool_result", "tool_use_id": "toolu_abc123", "content": "72°F and sunny"} ]} ] }' ```
Extended Thinking
Opus 4.6 and Sonnet 4.6: Use adaptive thinking. `budget_tokens` is deprecated on both Opus 4.6 and Sonnet 4.6. Older models: Use `"type": "enabled"` with `"budget_tokens": N` (must be < `max_tokens`, min 1024).
```bash
Opus 4.6: adaptive thinking (recommended)
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": "{{OPUS_ID}}", "max_tokens": 16000, "thinking": { "type": "adaptive" }, "output_config": { "effort": "high" }, "messages": [{"role": "user", "content": "Solve this step by step..."}] }' ```
Required Headers
| Header | Value | Description |
|---|---|---|
| `Content-Type` | `application/json` | Required |
| `x-api-key` | Your API key | Authentication |
| `anthropic-version` | `2023-06-01` | API version |
| `anthropic-beta` | Beta feature IDs | Required for beta features |