Bottom line
Head-to-head comparison of GPT-4o and Claude 4 on real coding tasks. We tested bug fixes, refactoring, and API integrations.
GPT-4o and Claude 4 are the two dominant choices for coding assistance. We put both through identical engineering challenges to see which one actually delivers better code.
Quick Verdict
| Use Case | Winner |
|---|---|
| Bug fixes | Claude 4 |
| Fast prototyping | GPT-4o |
| Code review | Claude 4 |
| Tool use / agents | GPT-4o |
Test Results
Bug Fix: Memory Leak in Node.js
Prompt: Find and fix a memory leak in this Express middleware.
| Model | Score | Root Cause Found | Fix Quality |
|---|---|---|---|
| GPT-4o | 8.8 | ✓ Yes | Good |
| Claude 4 | 9.4 | ✓ Yes | Excellent |
Claude 4 identified the event listener not being removed. GPT-4o suggested a fix that would have worked but missed the root cause.
Refactor: React Class to Hooks
Prompt: Convert this class component to functional with hooks.
| Model | Score | Correctness | Idiomatic |
|---|---|---|---|
| GPT-4o | 9.0 | 100% | 85% |
| Claude 4 | 9.3 | 100% | 95% |
API Integration: Stripe Webhook
Prompt: Write a Stripe webhook handler with signature verification.
| Model | Score | Security | Completeness |
|---|---|---|---|
| GPT-4o | 9.1 | ✓ Proper | Complete |
| Claude 4 | 9.5 | ✓ Proper + edge cases | Complete |
Speed Comparison
| Model | First Token | Full Response |
|---|---|---|
| GPT-4o | 0.8s | 4.2s |
| Claude 4 | 1.4s | 6.8s |
GPT-4o is nearly 2x faster.
Cost
| Model | Input | Output |
|---|---|---|
| GPT-4o | $2.50/1M | $10.00/1M |
| Claude 4 | $3.00/1M | $15.00/1M |
Recommendation
- Use GPT-4o for: Speed, agents, tool-heavy workflows
- Use Claude 4 for: Code quality, debugging, review
Many teams use both — GPT-4o for generation, Claude 4 for review.