Anthropic Streaming

Anthropic-compatible streaming

Endpoint: POST /api/anthropic/v1/messages

This endpoint accepts Anthropic Messages API payloads and streams Anthropic SSE events (message_start, content_block_start, content_block_delta, message_delta, message_stop). It is compatible with tools like Claude Code.

Request schema

  • model (string) – required
  • messages (array) – required, Anthropic-style content blocks are supported (text, image, tool_use, tool_result)
  • stream (boolean) – optional, must be boolean
  • max_tokens (int > 0) – required by Anthropic models
  • temperature (0..1), top_p (0..1), top_k (int > 0)
  • stop_sequences (string[]), metadata (object)
  • thinking (object), cache_control (object)
  • tool_choice (string | object), tools (array)
  • parallel_tool_calls (boolean)

Invalid shapes or incompatible values return HTTP 400 with a descriptive error.

Headers

  • x-api-key: $API_KEY or Authorization: Bearer $API_KEY
  • anthropic-version: 2023-06-01 (recommended)
  • Optional: anthropic-beta if you are opting into beta features

cURL (streaming)

curl -N -X POST "https://api.kushrouter.com/api/anthropic/v1/messages" \
  -H "x-api-key: $API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-3-5-sonnet-20241022",
    "messages": [{"role":"user","content":[{"type":"text","text":"Write a haiku about routers"}]}],
    "max_tokens": 256,
    "stream": true
  }'

Streaming frames

Events are emitted with explicit event: names per Anthropic spec. Example sequence:

:event: message_start
:data: {"type":"message_start","message":{...}}

:event: content_block_start
:data: {"type":"content_block_start","index":0,"content_block":{"type":"text"}}

:event: content_block_delta
:data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"..."}}

:event: message_delta
:data: {"type":"message_delta","delta":{}} 

:event: message_stop
:data: {"type":"message_stop"}

Tool use is reported via content/tool events. If tools are invoked, you'll receive tool ids and JSON arguments in subsequent events; then send a follow-up request with tool_result blocks to continue the conversation.

Errors

  • 400 – invalid JSON or unknown/unsupported parameters
  • 401 – missing or invalid API key
  • 413 – payload too large
  • 429 – rate limit exceeded (key or IP)
  • 5xx – transient errors
OverviewAPI Keys