Claude Developer Platform Release Notes

• We've raised the max_tokens cap to 300k on the Message Batches API for Claude Opus 4.6 and Sonnet 4.6. Include the output-300k-2026-03-24 beta header to generate longer single-turn outputs for long-form content, structured data, and large code generation tasks.

• We're retiring the 1M token context window beta for Claude Sonnet 4.5 and Claude Sonnet 4 on April 30, 2026. After that date, the context-1m-2025-08-07 beta header will have no effect on these models, and requests that exceed the standard 200k-token context window will return an error. To continue using 1M context windows, migrate to Claude Sonnet 4.6 or Claude Opus 4.6, which support the full 1M token context window at standard pricing with no beta header required.

Release notes

• The 1M token context window is now generally available for Claude Opus 4.6 and Sonnet 4.6 at standard pricing. Requests over 200k tokens work automatically for these models with no beta header required. The 1M token context window remains in beta for Claude Sonnet 4.5 and Sonnet 4.
• We've removed the dedicated 1M rate limits for all supported models. Your standard account limits now apply across every context length.
• We've raised the media limit from 100 to 600 images or PDF pages per request when using the 1M token context window.

Release notes

• We've launched automatic caching for the Messages API. Add a single cache_control field to your request body and the system automatically caches the last cacheable block, moving the cache point forward as conversations grow. No manual breakpoint management required. Works alongside existing block-level cache control for fine-grained optimization. Available on the Claude API and Azure AI Foundry (preview). Learn more in our prompt caching documentation.

• We've retired the Claude Sonnet 3.7 model (claude-3-7-sonnet-20250219) and the Claude Haiku 3.5 model (claude-3-5-haiku-20241022). All requests to these models will now return an error. We recommend upgrading to Claude Sonnet 4.6 and Claude Haiku 4.5 respectively. Researchers can request ongoing access through the External Researcher Access Program.

• We announced the deprecation of the Claude Haiku 3 model (claude-3-haiku-20240307), with retirement scheduled for April 19, 2026. We recommend migrating to Claude Haiku 4.5. Read more in model deprecations.

Release notes

• We've launched Claude Sonnet 4.6, our latest balanced model combining speed and intelligence for everyday tasks. Sonnet 4.6 delivers improved agentic search performance while consuming fewer tokens. Sonnet 4.6 supports extended thinking and a 1M token context window (beta). See Models & Pricing for details.

• API code execution is now free when used with web search or web fetch. Sandboxed code execution improves model capability and token efficiency. See the pricing details for standalone usage.

• The web search tool and programmatic tool calling are now generally available (no beta header required). Web search and web fetch now support dynamic filtering in public beta, which uses code execution to filter results before they reach the context window for better performance and reduced token cost.

• The code execution tool, web fetch tool, tool search tool, tool use examples, and memory tool are now generally available (no beta header required).

• We've launched Claude Opus 4.6, our most intelligent model for complex agentic tasks and long-horizon work. Opus 4.6 recommends adaptive thinking (thinking: {type: "adaptive"}); manual thinking (type: "enabled" with budget_tokens) is deprecated. Opus 4.6 does not support prefilling assistant messages. Learn more in What's new in Claude 4.6.

• The effort parameter is now generally available (no beta header required) and supports Claude Opus 4.6. Effort replaces budget_tokens for controlling thinking depth on new models.

• We've launched the compaction API in beta, providing server-side context summarization for effectively infinite conversations. Available on Opus 4.6.

• We've introduced data residency controls, allowing you to specify where model inference runs with the inference_geo parameter. US-only inference is available at 1.1x pricing for models released after February 1, 2026.

• The 1M token context window is now available in beta for Claude Opus 4.6, in addition to Sonnet 4.5 and Sonnet 4. Long context pricing applies to requests exceeding 200K input tokens.

• Fine-grained tool streaming is now generally available on all models and platforms (no beta header required). The output_format parameter for structured outputs has been moved to output_config.format.

Structured outputs

• Structured outputs are now generally available on the Claude API for Claude Sonnet 4.5, Claude Opus 4.5, and Claude Haiku 4.5. GA includes expanded schema support, improved grammar compilation latency, and a simplified integration path with no beta header required. The output_format parameter has moved to output_config.format. Existing beta users can continue using the beta header during the transition period. Structured outputs remain in public beta on Amazon Bedrock and Microsoft Foundry.