Claude Opus 4.6 and GPT-5.3 Codex Drop on the Same Day
Anthropic and OpenAI both release major coding model upgrades — Claude Opus 4.6 and GPT-5.3 Codex — intensifying the AI coding arms race.
Claude Opus 4.6 and GPT-5.3 Codex Drop on the Same Day
In a rare coincidence of timing, both Anthropic and OpenAI have released major coding model updates today. Claude Opus 4.6 and GPT-5.3 Codex each push the frontier of AI-assisted software development, giving developers two powerful new options to choose from.
Claude Opus 4.6
Anthropic's latest flagship model builds on the strong foundation of Opus 4.5, delivering meaningful improvements across the board for software engineering tasks.
What's New
- Doubled max output — 16K tokens, up from 8K in Opus 4.5, allowing larger single-pass code generation
- Improved agentic performance — better handling of long-horizon, multi-step coding tasks with fewer errors and less supervision required
- Stronger reasoning — notable gains on complex algorithmic and architectural challenges
- Better tool use — more reliable function calling and multi-tool coordination for autonomous workflows
Pricing and Availability
Claude Opus 4.6 is available now at $5 per million input tokens and $25 per million output tokens — the same pricing as Opus 4.5. Access it via the Claude API with model ID claude-opus-4-6, Claude apps, Amazon Bedrock, Google Vertex AI, and Microsoft Azure.
GPT-5.3 Codex
OpenAI follows up on the original GPT-5 Codex with a significant update that brings improved autonomous coding and broader API availability.
What's New
- Improved autonomous development — GPT-5.3 Codex handles more complex refactoring and feature implementation tasks with higher success rates
- Enhanced code review — even fewer false positives and more actionable suggestions than its predecessor
- Full-stack capabilities — stronger performance across frontend, backend, and infrastructure code
- API availability — unlike the original GPT-5 Codex which was limited to the Codex platform, GPT-5.3 Codex is accessible via the standard OpenAI API
Pricing and Availability
GPT-5.3 Codex is available at $1.50 per million input tokens and $12.00 per million output tokens via the OpenAI API with model ID gpt-5.3-codex.
Head-to-Head: How Do They Compare?
Both models represent the cutting edge for AI-powered coding, but they take different approaches:
| Claude Opus 4.6 | GPT-5.3 Codex | |
|---|---|---|
| Context Window | 200K tokens | 272K tokens |
| Max Output | 16K tokens | 32K tokens |
| Input Price | $5.00 / 1M tokens | $1.50 / 1M tokens |
| Output Price | $25.00 / 1M tokens | $12.00 / 1M tokens |
| Provider | Anthropic | OpenAI |
GPT-5.3 Codex offers a larger context window, higher max output, and lower pricing. Claude Opus 4.6 brings Anthropic's signature strengths in careful reasoning and safety alignment. The best choice depends on your specific workflow and priorities.
See Them In Action
Want to see how these models stack up on real coding tasks? Check out our code sample comparisons to compare Claude Opus 4.6, GPT-5.3 Codex, and dozens of other models side by side.
Both models are available now. We'll be generating fresh code samples with each in the coming days.