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I debug Rust and TypeScript code daily. I've used all three major AI APIs for this — Gemini, Claude, and GPT-4.
Here's the honest comparison for code debugging specifically. Not benchmarks. Actual use.
The test: real bugs from real projects
I ran the same 5 bugs through each model:
- A Rust borrow checker error with async context
- A React state update causing infinite re-render
- An Android logcat crash trace (NullPointerException chain)
- A subtle off-by-one in a PDF page index calculation
- A tokio task cancellation race condition
Gemini 2.5 Flash Preview (free)
Rust errors: Good. Understands the borrow checker well, suggests correct fixes.
React bugs: Strong. Identifies the stale closure / dependency array issue immediately.
Logcat traces: Excellent. Traces causality chains across multiple components.
Speed: 2–5 seconds. Fast enough for interactive use.
Cost: Free tier — 500 req/day
Best at: multi-component causality, Android-specific knowledge, speed.
Claude Sonnet (paid)
Rust errors: Excellent. Best at explaining why the borrow checker is rejecting the code, not just what to change.
React bugs: Excellent. Explains the mental model clearly, not just the fix.
Logcat traces: Good, but less Android-specific knowledge than Gemini.
Speed: 3–8 seconds.
Cost: ~$3–15/month depending on usage
Best at: explaining reasoning, teaching mode, complex Rust lifetime errors.
GPT-4o (paid)
Rust errors: Good, but occasionally suggests fixes that don't compile.
React bugs: Good. Standard answers, correct but rarely insightful.
Logcat traces: Adequate. Generic Android debugging advice.
Speed: 2–4 seconds.
Cost: ~$5–20/month depending on usage
Best at: broad knowledge, consistent quality, plugin ecosystem.
Summary table
| Gemini 2.5 Flash | Claude Sonnet | GPT-4o | |
|---|---|---|---|
| Rust debugging | ✅ Good | ✅ Best | ✅ Good |
| React debugging | ✅ Good | ✅ Best | ✅ Good |
| Android/logcat | ✅ Best | ✅ Good | ⚠️ Adequate |
| Explanation quality | ✅ Good | ✅ Best | ✅ Good |
| Speed | ✅ Fast | ⚠️ Medium | ✅ Fast |
| Free tier | ✅ Yes | ❌ No | ❌ No |
My actual workflow
Daily debugging: Gemini 2.5 Flash (free, fast, good enough)
Complex Rust lifetime issues: Claude (worth paying for the explanation quality)
Everything else: Gemini first, Claude if Gemini misses it
For a solo developer on a budget: start with Gemini free tier. It handles 90% of debugging tasks. Add Claude for the 10% where explanation quality matters.
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