Improve Code Quality with Claude Anthropic

Writing clean code is hard, but keeping code clean is even harder.

Codebases often become sprawling collections of ad-hoc fixes, duplicated logic, and fragile edge cases as teams grow, features evolve, and product deadlines loom. This can lead to systems that are difficult to extend, debug, or even understand.

Code maintainability isn’t just about elegance; it directly impacts developer productivity, onboarding time, and long-term system resilience. And that’s where Claude comes in.

Claude can help engineering teams refactor and maintain better code using two powerful tools:

• Claude.ai: Anthropic’s AI coding tool, accessible in your browser, is ideal for structured code generation, architectural planning, and small-scale refactoring. It provides a quick feedback loop for improving naming conventions, simplifying functions, or designing modular interfaces.
• Claude Code: Anthropic’s agentic coding tool integrates directly with your local code repositories to audit files, detect anti-patterns, and suggest clean, testable updates at scale. It supports multi-file reasoning, semantic code search, and user-guided diffs.

In this article, we’ll explore how both tools can help you increase code maintainability, from one-off cleanups to organization-wide refactoring efforts.

Why Maintainability Matters

Poorly maintained code leads to:

• Longer onboarding times for new engineers
• Increased bug rates due to implicit dependencies and unclear logic
• Slower feature iteration as developers spend more time navigating the system rather than building
• Technical debt sprawl as each new feature adds to the entropy

Well-maintained code, on the other hand, allows teams to move faster and more resiliently. You can ship features with fewer regressions. You can slash debugging time. You can onboard new engineers in weeks instead of months.

Claude helps teams bake maintainability into their daily workflows.

Getting Started with Claude.ai: Small Changes, Fast Loops

Claude.ai is great for early-stage cleanup, architectural brainstorming, and interface design. It’s accessible via web, desktop, and mobile, and it’s generally free to use.

Improve Naming, Modularization, and Structure

Prompt Claude with code snippets and ask for maintainability improvements:

Refactor this function to be more readable and follow the single responsibility principle.

Claude will return a cleaned-up version with:

• More descriptive variable and function names
• Logically separated side effects
• Extracted helper methods
• Inline comments for clarity

This is especially useful for:

• Reviewing pull requests before merging
• Mentoring junior developers on clean coding patterns
• Planning large-scale architectural changes

Refactor Boilerplate Code into Reusable Modules

Many teams struggle with duplicated logic, especially in utility files, database queries, and form validations. Claude.ai can identify patterns and suggest reusable abstractions.

Example prompt:

Here are three data validation functions. Can you extract the shared logic into a common helper and simplify the rest?

Claude will return modularized code with well-scoped helpers, saving time and improving consistency across files.

Explain Legacy or Opaque Code

Sometimes the first step in maintenance is understanding what you’re even looking at.

Paste in a legacy function and ask:

Explain what this code does, and suggest how to modernize it using async/await and error handling.

Claude will walk through the logic line by line, highlight performance bottlenecks, and suggest replacements.

Scaling Up with Claude Code: Agentic Terminal Refactoring

While Claude.ai excels at lightweight and conceptual tasks, Claude Code is built for deep integration.

Install it in your terminal with:

npm install -g @anthropic-ai/claude-code

Claude Code runs within your terminal and connects directly to your code repositories. Once initialized, it understands your full project context—including directory structure, code semantics, and test outputs.

What Makes Claude Code Different?

• One-time Initialization: You only need to start Claude Code once per session. No need to call it for every prompt.
• Multi-File Awareness: Claude tracks dependencies, file structure, and naming conventions across the codebase.
• Guided Diffs: Claude shows you proposed changes before applying them, so you stay in control.
• Project Memory: Using a CLAUDE.md, you can store preferred patterns, linter rules, and architectural principles.

Refactoring Workflows with Claude Code

Here’s how Claude Code can help you improve code maintainability across the lifecycle.

Audit for Code Smells and Anti-Patterns

Run:

find all functions longer than 50 lines and recommend splits

Claude will return a list of long functions with inline suggestions to extract helpers, move the logic to a service, or isolate side effects. You can then selectively apply those suggestions.

Other prompt ideas:

• find all classes with more than three dependencies and suggest decoupling strategies
• find all duplicated code blocks and propose shared functions
• find all functions that call external APIs without error handling

Auto-Generate Tests to Catch Regressions

Tests are the cornerstone of any maintainable codebase. Claude Code can automatically generate unit or integration tests for existing functions or modules using your preferred framework:

generate unit tests for this function using Jest

Claude will automatically detect dependencies, mock external services, and assert edge cases. You can customize as needed and then save them to your code.

Bulk Clean and Modernize Code

Claude Code excels at making codebase-wide updates. For example, you could kick off a project to rename API endpoints, update dependencies, or enforce consistent formatting rules.

Example:

rename all instances of 'oldAPI' to 'newAPI' across the project

Claude will show a list of diffs that you can review and commit. This is much faster than manual search-and-replace, and it avoids human error.

Document Components and APIs

Good documentation is crucial for maintainability. Have Claude Code generate it for you:

generate JSDoc comments for all functions in this file

Claude will analyze the parameters, return types, and signatures to generate clear, comprehensive documentation. You can then customize it to add more context, and maintain the documentation alongside your code.

Integrating Claude into Your Workflow

Maintainable code requires ongoing effort, and Claude can help you bake those efforts into your daily development cycle.

Create a “Maintainability Checklist”

Distill Claude’s prompts into actionable tasks and integrate them into your pull request templates. For example:

• Run a code smell audit before merging
• Generate unit tests for new functions
• Review naming conventions

Automate Code Review Processes

Use Claude Code as a pre-commit hook or CI/CD step to automate code review. Claude can flag potential issues and ensure code conforms to standards.

Establish a Culture of Knowledge Sharing

Encourage team members to use Claude.ai to explain legacy code, share best practices, and mentor junior developers. Using Claude is more than just a tool—it’s a way to build a more collaborative and maintainable codebase.

Conclusion

Maintaining code maintainability is a long-term investment that pays off in developer productivity, software quality, and business agility. Claude.ai and Claude Code offer a powerful set of tools to help you achieve this goal—from small cleanup tasks to large-scale refactoring efforts. By integrating Claude into your daily workflow, you can bake maintainability into your code, ensuring your projects remain robust, efficient, and enduring.