Anthropic ships Claude API 2026-10-21 with user profiles and Apache 2.0 SDKs
Anthropic released Claude API version 2026-10-21 on October 21, 2026, according to the Claude Platform release notes. A migration guide covers upgrading existing integrations, and new versions of every official client library now send the 2026-10-21 version header by default.
The client releases span Python SDK 2.0.0, TypeScript SDK 1.0.0, C# SDK 13.0.0, Go SDK 2.0.0, Java SDK 3.0.0, PHP SDK 1.0.0, Ruby SDK 2.0.0 and the ant CLI 2.0.0. These versions include breaking changes that do not depend on the API version, and all of them move from the MIT License to Apache 2.0, which gives enterprises clearer patent and contributor terms when embedding the SDKs in commercial distributions.
The headline feature is the launch of user profiles. Platforms, gateways and API resellers can now tell Anthropic which of their end customers each API request is for, so a safety enforcement action can apply to a single end customer instead of the provider's entire organization. The SDKs and the ant CLI support the new /v1/user_profiles endpoints.
Alongside profiles, new enforcement_status and enforcement_actions fields show whether Anthropic has restricted or banned an end customer. Developers can list profiles with the new enforcement_status[] filter to find accounts with an open restriction, giving multi-tenant products a way to isolate abuse without platform-wide outages.
Anthropic also added organization webhooks to the Admin API, in beta under the webhooks-2026-10-07 header. The /v1/organizations/webhooks endpoints register webhook URLs for two event types - one fired when Anthropic restricts or bans one of an organization's user profiles, and one when that restriction or ban ends. Access requires contacting an Anthropic account team.
For SaaS builders and AI gateway operators, the update resolves a longstanding multi-tenancy risk: one rogue end customer triggering action against a provider's whole API access. Teams planning to upgrade should read the 2026-10-21 migration guide first, since both the API version and the new SDK majors carry breaking changes.