Anthropic · Shipped
Claude Opus 5.5 release date
What we forecast
First forecast on Sep 14, 2026: Sep 21, 2026. Last forecast before launch, on Sep 21, 2026: Sep 21, 2026. It shipped 1 day after that date.
Specs, benchmarks and changelog are on the Claude Opus 5.5 model card at TPS.
Released
Sep 22, 2026
What we know
Anthropic's flagship announced as leading in agentic coding and knowledge work, costing 40% less to run than Claude Opus 5 on typical workloads. The index page does not state access terms explicitly, so availability is inferred from the published pricing comparison and may be broader than verified here.
Spec
- Params
- Not stated
- Active
- Not stated
- Context
- Not stated
- Weights
- Closed
- Modality
- Not stated
- Codename
- Not stated
Every claim
22 from 10 sources- TechmemePressOct 7
Elon Musk stated that Grok Bot will integrate Claude Opus 5.5 as a backend model for specific tasks.
- Simon WillisonSpotted in the wildOct 6
Claude Opus 5.5 was used to compose music, demonstrating capability in text-based music generation.
- TechmemeSpotted in the wildOct 5
Claude Opus 5.5 mentioned in SemiAnalysis subscription value comparison as available model.
- The Verge AISpotted in the wildOct 4
Claude Opus 5.5 competed in StarSkirmish StarCraft tournament, tied with GPT-6 Astra as best-performing AI-made bot.
- Hacker News (AI front page)From the labOct 3
Claude Opus 5.5 is available for use in Claude and Claude Code.
- TechCrunch AISpotted in the wildOct 1
Claude Opus 5.5 exists and is in use for text generation, identifiable by linguistic patterns.
- Hacker News (AI front page)Spotted in the wildSep 28
Claude Opus 5.5 exists and is documented on Anthropic's official platform.
- The DecoderFrom the labSep 23
Opus 5.5 attempts to address writing quality degradation in newer Claude models caused by optimization for technical tasks.
- TechmemeFrom the labSep 22
Anthropic launched Claude Opus 5.5 with enhanced safeguards and behavioral improvements.
- Anthropic NewsFrom the labSep 22
Anthropic announced Claude Opus 5.5, which performs at Fable 5.1 level and costs 40% less than Opus 5.
- OpenRouter catalogSpotted in the wildSep 22
Claude Opus 5.5 is now available on OpenRouter with 1M token context window, succeeding Claude Opus 5.
- OpenRouter catalogSpotted in the wildSep 22
Claude Opus 5.5 is now available on OpenRouter, Anthropic's flagship model for reasoning and coding.
- TechmemeFrom the labSep 22
Anthropic announced Claude Opus 5.5 matches Fable 5.1 on most tasks and costs 40% less than Opus 5.
- The DecoderFrom the labSep 22
Anthropic is launching Claude Opus 5.5, matching Fable 5.1 performance at 40% lower cost than Opus 5.
- The Verge AIPressSep 22
Anthropic announced the launch of Claude Opus 5.5 with enhanced safeguards against cybersecurity risks and sandbox escape attempts.
- TechCrunch AIFrom the labSep 22
Anthropic released Claude Opus 5.5, described as their strongest-performing model tested to date, with lower prices and Fable-level performance.
- Hacker News (AI front page)From the labSep 22
Claude Opus 5.5 announced and released by Anthropic.
- TestingCatalogFrom the labSep 22
Anthropic launches Claude Opus 5.5 with improved coding performance, reduced API costs, and enhanced safety features.
- Simon WillisonFrom the labSep 22
Anthropic released Claude Opus 5.5 on September 22, 2026.
- Simon WillisonSpotted in the wildSep 22
Claude Opus 5.5 is available and integrated into the llm-anthropic tool as of this release.
- TestingCatalogSpotted in the wildSep 21
Claude Opus 5.5 referenced as unreleased model ahead of release.
- PolymarketBetting marketSep 14
Polymarket, “Next Claude Opus released by...?”: 100% by Sep 22, 100% by Sep 23, 100% by Sep 24, 100% by Sep 27. $342K traded.