Chat Completion Chunk Object
Claude Chat Completion Chunk Object#
Claude's native streaming response emits content incrementally as event chunks, typically over SSE or a continuous event stream.Common Event Types#
message_start: The message begins
content_block_start: A content block begins
content_block_delta: Incremental update to a content block
message_delta: Update to message-level fields
message_stop: The message ends
Usage Tips#
Assemble the text content in event order
If tool calls or thinking segments are present, handle them block by block as well
Only treat the response as complete after receiving the stop event
Last verified/modified: 2026-09-28 (reviewed, no changes needed)
Modified at 2026-09-28 12:54:51