Cursor is the strongest fit for debugging because it is a code-native IDE that can read your entire file, trace execution context, and explain exactly why a bug is occurring while suggesting a fix inline. It understands your codebase structure rather than treating the code as a standalone snippet. Deepseek Coder is a solid free alternative if you want to paste code into a chat interface without a subscription. Claude Sonnet is worth considering when the bug involves complex logic that benefits from detailed step-by-step reasoning. GitHub Copilot works well if you prefer staying inside VS Code with a lighter-weight assistant.