# Claude Opus 5.5

Claude Opus 5.5 is an Anthropic language model released Sep 22, 2026; Anthropic's newest language model in our dataset is Claude Haiku 5.5. Proprietary, API access only. Anthropic's recommended starting model for most workloads, which Anthropic says leads in agentic coding and knowledge work. Verified against vendor sources on Oct 26, 2026.

Last verified: 2026-10-26 · Evidence: Reported · Canonical: https://theagenticweekly.com/models/claude-opus-5-5 · JSON: https://theagenticweekly.com/api/models/claude-opus-5-5

## Key facts

| Fact | Value | Source |
|---|---|---|
| Vendor | Anthropic |  |
| Released | Sep 22, 2026 | https://www.anthropic.com/news |
| API id | `claude-opus-5-5` | https://platform.claude.com/docs/en/about-claude/models/overview |
| Context window | 1,000,000 tokens (1M) | https://platform.claude.com/docs/en/about-claude/models/overview |
| Max output | 128,000 tokens | https://platform.claude.com/docs/en/about-claude/models/overview |
| Input | text, image | https://platform.claude.com/docs/en/about-claude/models/overview |
| Output | text | https://platform.claude.com/docs/en/about-claude/models/overview |
| Licence | Proprietary (API) | https://platform.claude.com/docs/en/about-claude/models/overview |
| Pricing | $4 in / $20 out per 1M tokens | https://platform.claude.com/docs/en/about-claude/models/overview |

## Vendor claims and neutral signals

- Vendor claim (Anthropic newsroom): "leads in agentic coding and knowledge work, and costs 40% less to run than Opus 5 on typical workloads."
- Anthropic's models overview says to start with Opus 5.5 for most workloads.

## What we tested

Nothing yet. We have not run Claude Opus 5.5 ourselves, so every fact here is Reported from the sources below.

## Sources

- [Anthropic models overview](https://platform.claude.com/docs/en/about-claude/models/overview)
- [Anthropic newsroom](https://www.anthropic.com/news)

Data licence: CC BY 4.0. Data: Agentic Weekly (https://theagenticweekly.com), CC BY 4.0.