Codex CLI vs Sonnet 4.5
A comprehensive 2026 comparison to help you choose the right AI tool for your needs. We tested both extensively.
Quick Verdict: Codex CLI vs Sonnet 4.5
After extensive testing, **Claude Sonnet 4.5** comes out ahead with a 4.8/5 rating. It's the better choice for most users, especially those focused on Daily coding tasks, writing, general use. However, Codex CLI remains competitive and may be preferable if you prioritize Rapid prototyping, open-source flexibility, ChatGPT users.
Claude Sonnet 4.5 edges out Codex CLI with superior overall performance and features that make it the better choice for most users in 2026. With a 4.8/5 rating, it excels particularly in Daily coding tasks, writing, general use.
Try Sonnet 4.5 FreeFeature Comparison Table
Side-by-side comparison of key features and capabilities
When to Use Codex CLI vs Sonnet 4.5
Choose Codex CLI When You Need:
- Rapid prototyping, open-source flexibility, ChatGPT users
- Testing capabilities with a free tier before committing
Choose Sonnet 4.5 When You Need:
- Daily coding tasks, writing, general use
- Better quality content writing and creative tasks
- Processing longer documents with 200K context
- Testing capabilities with a free tier before committing
In-Depth Analysis: Codex CLI vs Sonnet 4.5
Performance & Capabilities
In our comprehensive testing for 2026, we evaluated both Codex CLI and Claude Sonnet 4.5 across multiple dimensions including coding tasks, creative writing, reasoning problems, and general conversation quality. Claude Sonnet 4.5 emerged as our top pick with an overall rating of 4.8/5.
Codex CLI scored 4.7/5 on coding tasks, making it an excellent choice for developers. In comparison, Claude Sonnet 4.5 achieved 4.7/5 in this category.
Pricing & Value
When it comes to pricing, both tools offer free tiers, making them accessible for testing. For paid plans, Claude Sonnet 4.5 is more affordable at $20/month compared to $20/month.
Use Cases & Target Audience
Codex CLI is particularly well-suited for Rapid prototyping, open-source flexibility, ChatGPT users. Its strengths make it ideal for professionals who need advanced coding help, quality content creation, and reliable AI assistance.
Claude Sonnet 4.5, on the other hand, excels at Daily coding tasks, writing, general use. Users who prioritize fast response times, complex reasoning, will find it particularly valuable.
Codex CLI Pros & Cons
Pros
- Open source (Apache 2.0)
- Multimodal input support
- Local-first privacy
- Rich approvals workflow
- Included with ChatGPT subscription
Cons
- Newer tool with evolving features
- Less mature than Claude Code
Claude Sonnet 4.5 Pros & Cons
Pros
- Best value for money
- Excellent writing quality
- Fast response times
- Strong coding abilities
- Free tier available
Cons
- Not as powerful as Opus for complex tasks
- Usage limits on free tier
Best For: Codex CLI
Rapid prototyping, open-source flexibility, ChatGPT users
Best For: Sonnet 4.5
Daily coding tasks, writing, general use
Frequently Asked Questions
Common questions about Codex CLI vs Sonnet 4.5
Is Codex CLI better than Claude Sonnet 4.5 in 2026?
Based on our benchmarks and analysis, Claude Sonnet 4.5 performs better overall with a rating of 4.8/5. However, the best choice depends on your specific needs - Codex CLI excels at Rapid prototyping, open-source flexibility, ChatGPT users, while Claude Sonnet 4.5 is better for Daily coding tasks, writing, general use.
What is the price difference between Codex CLI and Sonnet 4.5?
Codex CLI offers a free tier and costs $20/month for paid plans. Claude Sonnet 4.5 offers a free tier and costs $20/month for paid plans.
Which is better for coding: Codex CLI or Sonnet 4.5?
For coding tasks, Claude Sonnet 4.5 scores higher with a 4.7/5 coding rating compared to 4.7/5.
Can I use Codex CLI and Sonnet 4.5 for free?
Codex CLI does offer a free tier with limited features. Claude Sonnet 4.5 does offer a free tier with limited features. Both tools offer trial periods or limited free access for new users.
Which AI has a larger context window: Codex CLI or Sonnet 4.5?
Claude Sonnet 4.5 has a larger context window at 200,000 tokens, compared to 128,000 tokens. Larger context windows allow processing more text in a single conversation.
Is Codex CLI faster than Sonnet 4.5?
In our speed tests, Claude Sonnet 4.5 is faster with a speed rating of 4.6/5. Response times can vary based on server load and query complexity.
Which is better for writing content: Codex CLI or Sonnet 4.5?
For content writing, Claude Sonnet 4.5 excels with a writing rating of 4.9/5 versus 4.3/5. Consider your specific writing needs when choosing.
Do Codex CLI and Sonnet 4.5 support image generation?
Codex CLI supports image understanding and analysis. Claude Sonnet 4.5 supports image understanding and analysis. For dedicated image generation, consider specialized tools like DALL-E or Midjourney.
Which AI should beginners choose: Codex CLI or Sonnet 4.5?
For beginners, we recommend starting with either - both offer free tiers to experiment. Claude Sonnet 4.5 has a slightly better overall user experience based on our testing.
Can I switch from Codex CLI to Sonnet 4.5 easily?
Yes, switching between AI tools is straightforward since they use similar prompting interfaces. Your conversation history won't transfer, but you can export important outputs. Many professionals use both tools depending on the task - Codex CLI for Rapid prototyping, open-source flexibility, ChatGPT users and Claude Sonnet 4.5 for Daily coding tasks, writing, general use.
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Ready to Get Started?
Both tools offer free tiers or trials. Try them out and see which one works best for your workflow in 2026.