Table of contents

• Model capabilities & benchmarks
• Hallucination & accuracy
• Long-form & multi-file programming
• Reasoning & explainability
• Table comparison
• Integrating Graphite's Diamond for code review
• Summary & recommendation
• Further tips
• Conclusion

Software developers increasingly rely on AI assistants to generate, review, and debug code. Two major contenders—Anthropic's Claude and OpenAI's ChatGPT—each excel in different ways. This guide provides a side-by-side comparison of their programming capabilities, with concrete examples and a look at how Graphite's Diamond tool can help review code generated by these AI tools.

1. Model capabilities & benchmarks

Claude (Opus/Sonnet 4)

• Excels at software engineering, scoring 72.5% on the SWE-bench benchmark.
• Supports massive ~200k token context windows.
• Includes hybrid reasoning: fast responses or detailed breakdowns.

ChatGPT (GPT-4o / GPT-4.1)

• Strong for code generation and debugging.
• ~128k token context windows.
• Extensive plugin support, including file uploads and browsing.

2. Hallucination & accuracy

• Claude tends to hallucinate less and is better at outputting syntactically and semantically correct code.
• ChatGPT can hallucinate more frequently, especially with ambiguous prompts or niche frameworks.
• On human-eval style tests, Claude shows slightly higher accuracy in code correctness.

3. Long-form & multi-file programming

• Claude's larger context makes it better at handling large codebases and multi-file dependencies.
• ChatGPT's multi-file abilities are functional but require more structured prompting or file uploads.
• Claude is often preferred for projects requiring architectural changes across multiple modules.

4. Reasoning & explainability

• Claude can explain its code generation steps through "thinking summaries," which are more transparent than typical outputs.
• ChatGPT is strong in debugging and can explain logic but sometimes omits deeper reasoning.
• Both models can answer "why" and "how" questions about code, but Claude provides more interpretive depth.

6. Table comparison

7. Integrating Graphite's Diamond for code review

No matter how reliable, AI-generated code still needs to be reviewed before pushing it into production. Diamond is a powerful AI code review tool from Graphite which can assist in reviewing AI-generated code:

• Automated PR review: Identifies bugs, performance issues, and style violations.
• Security enforcement: Applies custom rules for your codebase.
• Signal-rich feedback: Avoids noise by focusing on high-value suggestions.
• CI integration: Compatible with GitHub pull requests and doesn't require installing agents.

Example workflow:

1. Generate code with Claude or ChatGPT.
2. Submit a pull request.
3. Diamond reviews the code for security, correctness, and conventions.
4. Review flagged issues and make any needed corrections.

Diamond acts as a guardrail, especially for large-scale or automated code changes.

8. Summary & recommendation

• Choose Claude for deep reasoning, multi-file refactoring, and fewer hallucinations.
• Choose ChatGPT for plugin-driven tasks, quick iterations, and better integration options.
• Use Diamond regardless of the AI assistant to review, secure, and standardize your code.

9. Further tips

• Test both tools on your own codebase. Performance may vary.
• Refine prompts iteratively for better results.
• Combine AI tools with human oversight and static analysis.
• Use Diamond's customization options to enforce your team's review standards.

10. Conclusion

Claude is ahead in raw reasoning and complex code refactoring, while ChatGPT offers broader integrations and faster interactions. Combining either with a review tool like Diamond gives developers a powerful, safe way to leverage AI in their workflows. Ultimately, the best tool depends on your specific coding context—but pairing it with automated review makes all the difference.