# Claude Opus 4.8

Claude Opus 4.8 is a text generation model from Anthropic, available through the Impossibl API. Its published context window is 1,000,000 tokens. The advertised input rate is $5.00 per million input tokens. The advertised output rate is $25.00 per million output tokens.

- Model identifier: ` anthropic/claude-opus-4-8 `
- Creator: Anthropic
- Model type: Text generation
- Canonical model page: [Claude Opus 4.8](<https://impossibl.com/anthropic/claude-opus-4-8>)
- API availability: Listed as serving through Impossibl.
- Creator release date: 2026-05-28

## Capabilities and limits

- Context window: 1,000,000 tokens
- Maximum output tokens: Not published in the public catalog; this is separate from the context window.
- Inputs: text, image
- Outputs: text
- Tool calling: Not published

## API access

Use ` anthropic/claude-opus-4-8 ` as the model identifier through the Impossibl API.

Published API endpoints:

- ` /v1/chat/completions `

[API quickstart](<https://impossibl.com/docs/agent-quickstart>) · [Models and billing documentation](<https://impossibl.com/docs/models>)

## Published API prices

All rates are in USD. An unpublished rate is unknown, not zero. Workspace-specific pricing, taxes, balance-purchase fees, billing adjustments, and tool charges can affect the amount paid.

| Usage | Published base rate | Billing unit |
| --- | --- | --- |
| Input | $5.00 | per million input tokens |
| Output | $25.00 | per million output tokens |
| Cache read | $0.50 | per million cached input tokens |
| Cache write (default retention) | $6.25 | per million tokens |
| Cache write (one-hour retention) | $10.00 | per million tokens |
| Audio input | Not published | per million audio input tokens |

## Independent benchmarks

Source: [Artificial Analysis](<https://artificialanalysis.ai/>). Last checked: 2026-09-11T10:50:14.034Z.
Configurations are evaluated separately. API scores retain their original units. Unmeasured scores are omitted.

### Claude Opus 4.8 (Adaptive Reasoning, Max Effort)

Source: [Evaluation source](<https://artificialanalysis.ai/models/claude-opus-4-8>)

| Benchmark | Score |
| --- | --- |
| Intelligence Index | 41.99 |
| Omniscience Index | 28.75 |
| GPQA | 92.02% |
| Humanity’s Last Exam | 48.66% |
| SciCode | 54.40% |
| CritPt | 20.86% |
| Terminal-Bench v2.1 | 84.64% |
| Terminal-Bench v4.0 | 21.72% |
| Terminal-Bench Hard | 58.33% |
| AA-LCR | 77.67% |
| Multilingual LCR | 45.56% |
| Harvey LAB | 91.08% |
| GDPval Elo | 1489.04 |
| GDP.pdf All-pass | 22.80% |
| AutomationBench Partial | 45.59% |
| AnalystAgent | 45.00% |
| IFBench | 62.24% |
| Tau2 | 94.44% |
| Tau Banking | 34.23% |
| coding index (API) | 74.3 |
| agentic index (API) | 42.6 |
| intelligence index (API) | 42 |

Full benchmark data and breakdowns: [Complete benchmark snapshot](<https://api.impossibl.com/v1/models/anthropic/claude-opus-4-8/benchmarks>).


## Availability and retirement

The model is listed as serving. No retirement is announced in the current public catalog.

## Frequently asked questions

### What is Claude Opus 4.8?

Claude Opus 4.8 is a text-generation model from Anthropic, available through the Impossibl API.

### How much does Claude Opus 4.8 cost?

Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens through the Impossibl API. Cache reads cost $0.50 per million tokens; cache writes cost $6.25 per million tokens; cache writes with one-hour retention cost $10.00 per million tokens. All rates are in USD.

### What is the context length of Claude Opus 4.8?

Claude Opus 4.8 has a 1,000,000-token context window through the Impossibl API.

### What inputs and outputs does Claude Opus 4.8 support?

Claude Opus 4.8 accepts text and image as input. Claude Opus 4.8 returns text.

### How do I use Claude Opus 4.8 through an API?

Claude Opus 4.8 is available through the Impossibl API. Use anthropic/claude-opus-4-8 as the model identifier with /v1/chat/completions. The quickstart explains how to create an API key and send your first request.

### When was Claude Opus 4.8 released?

Anthropic released Claude Opus 4.8 on May 28, 2026.

Sources: [Creator release announcement](<https://www.anthropic.com/news/claude-opus-4-8>)

## Sources and related links

Prices, limits, capabilities, endpoints, and availability come from the public Impossibl catalog. Creator documentation supplies descriptions and release dates where available; it does not override the published API offering.

- [Public Impossibl model catalog](<https://api.impossibl.com/v1/models>)
- [Full model directory as JSON](<https://impossibl.com/models.json>)
- [Claude Opus 4.8: model details and pricing](<https://impossibl.com/anthropic/claude-opus-4-8>)
- [Model directory](<https://impossibl.com/models>)