Anthropic launched Claude Sonnet 5.5 and Claude Haiku 5.5, lowered Sonnet 5.5 prompt cache

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Oct 27, 2026 18:18 UTC docs https://platform.claude.com/docs/en/release-notes/api

Anthropic launched Claude Sonnet 5.5 and Claude Haiku 5.5, lowered Sonnet 5.5 prompt cache read prices, and added new webhook event types and capabilities to their API.

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anthropic just dropped claude sonnet 5.5 and haiku 5.5! new models are always exciting for builders.

big api updates from anthropic: new models and cheaper prompt cache reads for sonnet 5.5. also, some interesting new webhooks for user profiles and org-wide web fetch controls.

Anthropic API changelog changed: https://platform.claude.com/docs/en/release-notes/api 240 added lines --- +++ @@ -71,3 +71,3 @@  -We've launched +We’ve launched Claude Models on Google Cloud (Anthropic managed) @@ -78,3 +78,3 @@  -We've released API version +We’ve released API version 2026-10-21 @@ -83,3 +83,3 @@ shows how to upgrade. -We've released new versions of the +We’ve released new versions of the client SDKs @@ -95,6 +95,6 @@ . -The new SDK and CLI versions also have breaking changes that don't depend on the API version, and they are licensed under Apache 2.0 instead of the MIT License. See +The new SDK and CLI versions also have breaking changes that don’t depend on the API version, and they are licensed under Apache 2.0 instead of the MIT License. See SDK and CLI changes . -We've added the +We’ve added the enforcement_status @@ -115,3 +115,3 @@ are out of beta for Claude Enterprise organizations. -We've launched +We’ve launched user profiles @@ -123,3 +123,3 @@ . -We've added +We’ve added organization webhooks @@ -132,3 +132,3 @@ endpoints -register webhook endpoints for two event types: one for when Anthropic restricts or bans one of your organization's user profiles, and one for when the restriction or ban ends. To request access, contact your Anthropic account team. +register webhook endpoints for two event types: one for when Anthropic restricts or bans one of your organization’s user profiles, and one for when the restriction or ban ends. To request access, contact your Anthropic account team. Organization admins can now turn off web fetch for their organization on the @@ -145,5 +145,5 @@ tool -now follows your organization's web fetch domain restrictions set on the +now follows your organization’s web fetch domain restrictions set on the Capabilities -page of the Claude Console. A URL, including one reached by a redirect, must pass both the organization's list and the +page of the Claude Console. A URL, including one reached