Latest Claude Model Version (Sept 2026)

Q: What is the API model ID for Claude Opus 5.5?

The API model ID is claude-opus-5-5. It shipped 22 September 2026 and is available to Pro, Max, and API subscribers, including automatic availability in Claude Code.

Q: Which Claude model should I use right now?

Start with Opus 5.5 for most workloads. For the best speed-and-intelligence balance: Sonnet 5.5. For the hardest reasoning and long-horizon agentic work: Fable 5.1. For high-volume simple tasks: Haiku 5.5.

Last refreshed: November 5, 2026

Direct Answer: The current Claude model lineup (November 2026) is Claude Fable 5.1 (top capability tier, 1M context), Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 — with Claude Opus 5, Sonnet 5, and Haiku 4.5 still available, and Claude Mythos 5.1 alongside Fable at the top tier. New releases ship automatically to Claude Code.

Anthropic ships new models roughly every few months, so the “latest model” question is really two questions: which model was released most recently, and which one should you be using. This page tracks both. The model releases below are listed newest first, and every entry is sourced from Anthropic’s official announcements or the Claude docs model overview.

Updated September 3, 2026

The two Claude Opus 5.5 models (standard + Extended Thinking) now ship automatically in Claude Code to Pro, Max, and API subscribers. This page reflects the current lineup. Correction (November 5, 2026): this note was originally dated September 3; Anthropic’s release notes date the Opus 5.5 launch to September 22, 2026.

Current Lineup (newest first)

Claude Haiku 5.5

Released: October 7, 2026 (claude-haiku-5-5). Anthropic’s fastest, cheapest model — high-volume, latency-sensitive work like classification, extraction, and routing. 1M-token context window, from $0.10 / $0.50 per million tokens. Available through the API, Claude Code, and Claude in Chrome.

Claude Sonnet 5.5

Released: September 28, 2026 (claude-sonnet-5-5). What Anthropic calls the best combination of speed and intelligence — the everyday workhorse at $2 / $10 per million tokens, with a 1M-token context window. Available through the API, Claude Code, and Claude in Chrome.

Claude Opus 5.5 (standard + Extended Thinking)

Released: September 22, 2026 (with Claude Opus 5.5 Extended Thinking). Anthropic’s recommended default for most workloads — long-running agentic coding and knowledge work. Available through the Claude API, Claude Code, and Claude in Chrome.

Claude Fable 5.1

Released: August 27, 2026. Anthropic’s most capable Claude model for complex reasoning, agentic coding, and long-context analysis at launch, still Anthropic’s top capability tier — the model its docs point to when Opus 5.5 at higher effort falls short. Its sibling model, Claude Mythos 5.1, shares the tier and its rate limits. 1M-token context window. Available through the API, Claude Code, and Claude in Chrome.

Claude Sonnet 5

Released: August 2026. The balanced workhorse — strong reasoning at lower cost and latency than the flagship tier. Default model for many Claude Code workflows. Succeeded by Claude Sonnet 5.5 (September 28, 2026); Sonnet 5 remains available.

Claude Haiku 4.5

Released: October 1, 2025 (claude-haiku-4-5-20251001). Fast, cheap, 200K context. The model for high-volume simple tasks — classification, extraction, quick answers. Succeeded by Claude Haiku 5.5 (October 7, 2026); Haiku 4.5 remains available.

How Claude Code Gets New Models

New Claude models ship automatically in Claude Code — no manual upgrade step. When Anthropic releases a model (like Opus 5.5 on September 22), it appears in Claude Code for eligible subscribers without reinstalling or reconfiguring. This is why the “current model” question matters: your tooling quietly changes underneath you.

Models Anthropic Retired in 2026

Claude Sonnet 4 / Opus 4 (original 4.0-generation): retired June 15, 2026. If your integrations still reference 20250514 date-string IDs, they’re broken — migrate.
Claude Opus 4.1: retired September 2026 alongside the Opus 5.5 launch.

Frequently Asked Questions

What is the API model ID for Claude Opus 5.5?

The API model ID is claude-opus-5-5. It shipped 22 September 2026 and is available to Pro, Max, and API subscribers, including automatic availability in Claude Code.

Is Claude Haiku 4.5 being retired?

Anthropic’s 2026 consolidation removed older models (Sonnet 4 and Opus 4 on 15 June 2026, Opus 4.1 in September), but Haiku 4.5 was succeeded as the fast model by Claude Haiku 5.5 on October 7, 2026. Haiku 4.5 remains available, and Anthropic has not announced a retirement date for it.

Is Claude Opus 5 still the current flagship model?

No. Anthropic’s top capability tier is now Claude Fable 5.1, and Claude Opus 5.5 (released 22 September 2026) is its recommended default for most workloads. Opus 5 remains available. See our Claude Opus 5.5 pricing guide for plan and API details.

Which Claude model should I use right now?

Anthropic’s own guidance: start with Opus 5.5 for most workloads. For the best speed-and-intelligence balance: Sonnet 5.5. For the hardest reasoning and long-horizon agentic work: Fable 5.1. For high-volume simple tasks: Haiku 5.5. New models appear automatically in Claude Code when released.

Do new Claude models require reinstalling Claude Code?

No. New models ship automatically to eligible subscribers — no reinstall, no config change.

Where is the official model list?

Anthropic maintains the canonical list at platform.claude.com/docs/en/about-claude/models/overview.

Tracking Claude Models for Your Team?

At Tygart Media, we build AI systems that stay current with Anthropic’s releases. See our Claude implementation services or browse the full Claude pricing and plans guide.

Part of the complete guide: Claude Pricing, Plans & Limits