Claude Model History

Anthropic released the first Claude model on Mar 14, 2023 and has shipped more than 30 since, through Claude 2, the Claude 3, 3.5 and 3.7 models, the Claude 4 family and the Claude 5 family that is current in Nov 2026. This page lists every release with its date, what it added and when it was retired.

The first Claude model was released on Mar 14, 2023, in two versions, Claude and the lighter Claude Instant (Introducing Claude, Anthropic, Mar 14, 2023), and by Nov 6, 2026 Anthropic had reached Claude Fable 5.1, Opus 5.5, Sonnet 5.5 and Haiku 5.5. Along the way the context window grew from 9K tokens to 1M, prices for the top tier fell from $15 and $75 per million tokens (Claude 3 Opus) to $4 and $20 (Opus 5.5), and the naming settled on Haiku, Sonnet and Opus, with Fable above them since Jun 2026. Every date below is from Anthropic's own posts; retirement dates are from its Model deprecations page, read Nov 6, 2026.

Quick facts

First release	Claude and Claude Instant, Mar 14, 2023
Latest release	Claude Haiku 5.5, Oct 7, 2026 (as of Nov 6, 2026)
Generations	Claude 1, 2, 3 (with 3.5 and 3.7), 4 (4 to 4.8), 5 (5 to 5.5)
Context window	9K tokens in Mar 2023; 1M on current models
First reasoning model	Claude 3.7 Sonnet, Feb 24, 2025
Never released	Claude 3.5 Opus, promised in Jun 2024
Oldest model still on the API	Claude Haiku 4.5, Oct 15, 2025 (as of Nov 6, 2026)

Sources: Models, Anthropic, read Nov 6, 2026; Introducing 100K Context Windows, Anthropic, May 11, 2023; Model deprecations, Anthropic docs, read Nov 6, 2026.

Claude 1 and Claude 2 (2023)

Mar 14, 2023: Claude and Claude Instant. Offered through a chat interface and an API after a closed alpha. Launch partners included Quora's Poe, Notion AI and DuckDuckGo's DuckAssist (Introducing Claude).
May 11, 2023: 100K context. The context window grew "from 9K to 100K tokens", about 75,000 words (Introducing 100K Context Windows).
Jul 11, 2023: Claude 2. 76.5% on the bar exam's multiple choice section and 71.2% on Codex HumanEval, and the public claude.ai beta in the US and UK.
Aug 9, 2023: Claude Instant 1.2. A faster, cheaper model (Releasing Claude Instant 1.2).
Nov 21, 2023: Claude 2.1. A 200K-token context window, about 150,000 words, half as many false statements as Claude 2.0, and system prompts.

Claude 1.x and Instant 1.x were retired on Nov 6, 2024; Claude 2.0 and 2.1 on Jul 21, 2025.

Claude 3, 3.5 and 3.7 (2024 to early 2025)

Mar 4, 2024: Claude 3 Opus and Sonnet, with Haiku announced; Haiku followed on Mar 13. The names Haiku, Sonnet and Opus begin here, all with 200K context and image input.
Jun 21, 2024: Claude 3.5 Sonnet, with Artifacts on Claude.ai.
Oct 22, 2024: an upgraded Claude 3.5 Sonnet, Claude 3.5 Haiku and computer use in public beta.
Feb 24, 2025: Claude 3.7 Sonnet, Anthropic's first model with extended thinking, launched with a research preview of Claude Code.

Details, benchmarks and retirement dates are on Claude 3 Models. The last of them, Claude 3 Haiku, retired on Apr 20, 2026.

Claude 4 (May 2025 to May 2026)

May 22, 2025: Claude Opus 4 and Sonnet 4, "hybrid models" with instant answers and extended thinking; Claude Code generally available.
Aug 5, 2025: Claude Opus 4.1.
Sep 29, 2025: Claude Sonnet 4.5, with the Claude Agent SDK.
Oct 15, 2025: Claude Haiku 4.5.
Nov 24, 2025: Claude Opus 4.5, with Opus prices cut to $5 and $25 and the effort setting.
Feb 5, 2026: Claude Opus 4.6, the first Opus with a 1M-token window and adaptive thinking.
Feb 17, 2026: Claude Sonnet 4.6.
Apr 7, 2026: Claude Mythos Preview, restricted to Project Glasswing.
Apr 16, 2026: Claude Opus 4.7, with a new tokenizer and the xhigh effort level.
May 28, 2026: Claude Opus 4.8.

Claude 5 (Jun 2026 to now)

Date	Model	What it added
Jun 9, 2026	Claude Fable 5 and Claude Mythos 5	A new tier above Opus at $10 and $50 per million tokens; suspended Jun 12 to Jul 1 under US export controls
Jun 30, 2026	Claude Sonnet 5	"The most agentic Sonnet model yet", $2 and $10
Jul 24, 2026	Claude Opus 5	Close to Fable 5 at half the price, $5 and $25
Sep 1, 2026	Claude Fable 5.1 and Claude Mythos 5.1	Cheaper cache reads, looser safeguards; Anthropic's newsroom lists it on Sep 15
Sep 22, 2026	Claude Opus 5.5	$4 and $20, thinking always on
Sep 28, 2026	Claude Sonnet 5.5	Faster and cheaper per task than Sonnet 5
Oct 7, 2026	Claude Haiku 5.5	First Haiku with effort control, from $0.10 and $0.50

Sources: Claude Fable 5 and Claude Mythos 5, Jun 9, 2026; Introducing Claude Sonnet 5, Jun 30, 2026; Introducing Claude Opus 5, Jul 24, 2026; Introducing Claude Mythos and Fable 5.1, Sep 15, 2026; Introducing Claude Opus 5.5, Sep 22, 2026; Introducing Claude Sonnet 5.5, Sep 28, 2026; Introducing Claude Haiku 5.5, Oct 7, 2026.

Sonnet 5 launched at an introductory $2 and $10 that was due to rise to $3 and $15 on Sep 1, 2026; an Aug 10 edit made the lower price permanent (Introducing Claude Sonnet 5). There is no Claude Haiku 5; the jump was from Haiku 4.5 to Haiku 5.5. See Claude Fable 5, Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5 and Claude Haiku 5.5.

A table with columns Sonnet 5 (highlighted), Sonnet 4.6 and Opus 4.8 For reference. SWE-bench Pro: 63.2%, 58.1%, 69.2%. Terminal-Bench 2.1: 80.4%, 67.0%, 82.7%. Humanity's Last Exam: 43.2%, 34.6%, 49.8% with no tools and 57.4%, 46.8%, 57.9% with tools. OSWorld-Verified: 81.2%, 78.5%, 83.4%. GDPval-AA v2: 1618, 1395, 1615. — Anthropic's Sonnet 5 launch table compares Sonnet 5 with Sonnet 4.6, with Opus 4.8 for reference, on five benchmarks. Anthropic

How the app default changed

5:30 Anthropic's launch posts trace the model Free users got by default: Claude 3 Sonnet (Mar 2024), Claude 3.5 Sonnet (Jun 2024), Sonnet 4 (May 2025), Sonnet 4.6 for Free and Pro (Feb 17, 2026) and Sonnet 5 for Free and Pro (Jun 30, 2026); Opus 5 became the default on Max on Jul 24, 2026 (Introducing Claude Sonnet 5; Introducing Claude Opus 5). The 5.5 posts do not name a new app default. In Claude Code, Opus 5.5 is the default on every paid plan (Model configuration, read Nov 6, 2026).

Retired and retiring models

Model	Retired on the Claude API
Claude 1.x and Instant 1.x	Nov 6, 2024
Claude 2.0, 2.1, Claude 3 Sonnet	Jul 21, 2025
Claude 3.5 Sonnet (both versions)	Oct 28, 2025
Claude 3 Opus	Jan 5, 2026
Claude 3.5 Haiku, Claude 3.7 Sonnet	Feb 19, 2026
Claude 3 Haiku	Apr 20, 2026
Claude Opus 4, Sonnet 4	Jun 15, 2026
Claude Opus 4.1	Aug 5, 2026
Claude Sonnet 4.5	Retires Nov 30, 2026

Source: Model deprecations, Anthropic docs, read Nov 6, 2026.

Anthropic promises at least 60 days' notice before retiring a public model, by email and in the docs, and says it has committed to keep the weights of past models long term, hoping to make them available again one day. Retirement dates cover Anthropic's own platforms; Amazon Bedrock and Google Cloud set their own, and Opus 4.1 and Sonnet 4 were still on some of those clouds on Nov 6, 2026 (Pricing, Anthropic docs).

Frequently asked questions

When did Claude first come out? Anthropic released the first Claude model, together with Claude Instant, on Mar 14, 2023. The free public claude.ai site opened with Claude 2 on Jul 11, 2023, in the US and UK.

What is the latest Claude model? As of Nov 6, 2026, the newest Claude model is Claude Haiku 5.5 (Oct 7, 2026). The most capable widely available one is Claude Fable 5.1, and Anthropic recommends Claude Opus 5.5 for most work.

Was there a Claude 3.5 Opus? No. Anthropic said in Jun 2024 that Claude 3.5 Opus would come later that year, but it never appeared in Anthropic's list of model releases.

Can I still use old Claude models? Claude Haiku 4.5 and every later model are still on the Claude API as of Nov 6, 2026, Claude Sonnet 4.5 only until Nov 30, 2026. Everything older is retired, except some Claude 4 and 4.1 models on partner clouds.

What Claude version am I using? In the Claude apps, the model name is shown next to the send button. In Claude Code, /model shows and changes it.