Free AI Code Reviewer & Refactoring Tool (No Signup Needed)

AI Code Reviewer & Refactoring Helper

Paste code, click Review, and get a short list of issues with quick fixes along with the complete updated code every time.

Note: If your team has a specific rule like early returns only, paste that rule on top of your code before you click Review and the tool will follow it.

I built this tool to give you quick, honest code reviews with concrete refactors that you can drop into your file right now. Paste your code, pick a focus like readability or performance, click Review, and you will get clear findings, minimal fixes, and small diffs you can apply in minutes. It runs in the browser, no signup, and it is safe to use for snippets and single files during your daily workflow.

Do not get lost. Hit Ctrl+D on Windows or Command+D on Mac to bookmark this tool for instant access.

What Is An AI Code Reviewer And Refactoring Helper

An AI code reviewer reads your code, reasons about intent, and flags issues that slow down teams. It points out poor naming that hides meaning. It highlights complexity that will break during maintenance. It calls out loops that do too much. It identifies duplication that should be a function. It then offers refactors that are easy to apply and safe to test.

A good reviewer gives feedback that is tight and useful. It focuses on what a human reviewer would say in a real pull request. It avoids nitpicking personal style and aims for cleaner design and reliable behavior. This tool mirrors that mindset. You get a summary, key findings with severity, minimal fixes, a quick estimate of cyclomatic complexity, pattern suggestions, and test ideas to confirm changes.

Why Developers Need Refactoring Help Before A Pull Request

You write code that works. Then you add a feature. Then you fix an edge case. Now the file reads like a time capsule. Variable names drift. A helper function grows extra branches. The happy path is no longer clear. Reviewers ask the same questions. You tweak lines again and again. You burn hours that should have gone into building.

A small pre review changes the flow. You paste the file, hit Review, and clean up the top three issues. The pull request focuses on design. The team spends less time arguing over names. You merge faster. You move on.

How To Use The Tool In Three Steps

  1. Paste the function or file into the input box
  2. Pick a mode if you have a priority like performance or maintainability
  3. Click Review and apply the minimal fixes shown in the output

Run your tests after the change. If you do not have tests, at least run the sample checks listed in the output. Then rerun the tool to confirm the new shape looks good.

What The Tool Checks In Practice

The tool looks at your code like a senior reviewer. It tries to understand intent. It looks for clarity first. It then examines branching and loops for complexity. It looks for early returns, guard clauses, and extraction chances. It checks for common performance traps like repeated JSON parses, expensive regex inside loops, new objects in tight loops, or N plus one queries. It flags duplication that wants a helper. It checks naming drift where a variable started as a count and then became a list. It prefers simple types that carry clear meaning.

Example Walkthrough 1: Readability Upgrade In JavaScript

Input snippet:

function getData(u){
  let a = fetch(u).then(r=>r.json()).then(d=>{
    let x = []
    for(let i=0;i<d.length;i++){
      if(d[i].type=="user"){
        x.push(d[i])
      }
    }
    return x
  })
  return a
}

Output:

Summary:
The code lacks error handling, uses nested promises instead of async/await for clarity, and has a verbose loop for filtering. Quick wins include converting to async/await, adding try/catch for errors, and using array filter for readability.

Issues:
1. [High] No error handling — fetch or JSON parsing errors will be unhandled — add try/catch.
2. [Medium] Uses nested .then() instead of async/await — reduces readability and maintainability — refactor to async/await.
3. [Low] Manual loop for filtering — verbose and less readable — use Array.prototype.filter.

Quick Fixes:
- Convert function to async and use await for fetch and json parsing.
- Wrap await calls in try/catch to handle errors gracefully.
- Replace for loop with filter to select items with type "user".

async function getData(u) {
  try {
    const response = await fetch(u);
    if (!response.ok) throw new Error('Network response was not ok');
    const data = await response.json();
    return data.filter(item => item.type === "user");
  } catch (error) {
    console.error('Fetch error:', error);
    return [];
  }
}

Example Walkthrough 2: Performance Fix In Python

Input snippet:

def find_names(records):
    result = []
    for r in records:
        if r.get("name"):
            result.append(r["name"].strip().lower())
    return list(set(result))

Output:

Summary:
The function is readable but can be improved for performance and maintainability by using a set comprehension directly and avoiding multiple lookups. Variable naming can be clearer. The quick win is to replace the loop with a set comprehension and simplify the return.

Issues:
1. [Medium] Inefficient use of list then set conversion — extra memory and processing — use a set comprehension directly.
2. [Low] Variable name 'r' is not descriptive — reduces readability — rename to 'record'.
3. [Low] Multiple dictionary lookups for the same key — minor inefficiency — store the value in a variable.
4. [Low] No input validation or type hints — affects maintainability — add type hints and consider input checks.

Quick Fixes:
- Replace the for-loop and list with a set comprehension that strips and lowers names.
- Rename loop variable to 'record' for clarity.
- Use a single dictionary get call per record.
- Add type hints to the function signature.

Updated Code:
def find_names(records: list[dict]) -> list[str]:
    return list({record["name"].strip().lower() for record in records if record.get("name")})

Example Walkthrough 3: Maintainability In Java

Input snippet

int total = 0;
for(Order o : orders){
  if(o.status.equals("PAID") || o.status.equals("CAPTURED") || o.status.equals("SETTLED")){
    total += o.amount;
  }
}

Output:

Summary:
The code is readable but can be improved for maintainability and slight performance by avoiding repeated string comparisons and using a set for status checks. Using streams can improve readability and conciseness. The quick win is to replace multiple equals checks with a set lookup.

Issues:
1. [Medium] Multiple string comparisons in loop — inefficient and error-prone if statuses change — use a Set for status checks.
2. [Low] Manual accumulation with for-loop — more verbose than necessary — consider using Java streams for clarity.
3. [Low] No null check on order status — potential NullPointerException — add null-safe checks.

Quick Fixes:
- Create a Set of valid statuses and check membership instead of multiple equals.
- Use Java streams with filter and mapToInt for concise summation.
- Add null check for order status before comparison.

Updated Code:
int total = orders.stream()
  .filter(o -> o.status != null && (o.status.equals("PAID") || o.status.equals("CAPTURED") || o.status.equals("SETTLED")))
  .mapToInt(o -> o.amount)
  .sum();

Best Practices For Getting Maximum Value

  • Scan one function or one file at a time
  • Apply the top one or two refactors only
  • Keep each change small and testable
  • Rerun the tool after changes to confirm shape and clarity
  • Add a quick test for new behavior where the output suggests a check

When To Choose Each Mode

  • Full Review when you want a balanced pass
  • Refactor Only when you already know the smell and want a small clean diff
  • Readability when the team struggles to parse the file
  • Performance when the code touches a hot path
  • Maintainability when the file grows new branches every sprint

Common Refactors You Will See Often

  • Extract function for a clear chunk of logic
  • Rename variable to match meaning
  • Replace nested if with guard return
  • Replace index loop with a map filter reduce chain
  • Use a set or map for constant time lookups
  • Move magic numbers into constants
  • Replace manual parsing with a standard library helper
  • Remove dead code that never runs

Simple Rules That Improve Code Quality Today

  • Functions should read top to bottom with a clear story
  • Names should carry intent and not shape
  • Fewer branches leads to fewer bugs
  • Data structures beat clever tricks
  • Prefer pure expressions over mutation in loops
  • Add a guard early when input can be missing

Still Have Questions?

What Does This Code Reviewer Do

It reads your code and returns a summary, key findings with severity, small refactor diffs, risk notes, and test ideas. The output is tight and focused on real changes you can apply fast.

Does It Work For Any Language

It works best for popular languages like JavaScript, TypeScript, Python, Java, C Sharp, Go, PHP, Rust, and SQL. Use the language hint when you paste code that uses uncommon patterns so the model does not misread intent.

Is My Code Safe When I Paste It

The tool sends your snippet to an API proxy that you control and it does not store the text for later reading. Use it for snippets and single files. Skip secrets and private keys in any paste.

Can I Use This For Entire Repos

Use it for one file at a time. Big reviews drown in noise. Small reviews lead to action you will take right now.

How Fast Is The Review

Short functions return in a few seconds. Large files take longer. If it takes too long, split the file by function and review in parts.

Can I Use It For Classroom Work

Yes. It helps students learn readable patterns and small refactors. It is also a good way to see before and after snapshots that make lessons stick.

Can I Tune It For My Team Style

Use the mode and language hint. If your team has a specific rule like early returns only, paste that rule on top of your code before you click Review and the tool will follow it.

Example Walkthrough 4: Maintainable SQL

Input snippet:

SELECT * FROM orders WHERE status = 'paid' OR status = 'captured' OR status = 'settled';

Output:

Summary:
The query uses repetitive OR conditions that reduce readability and may impact performance. Using IN improves clarity and can leverage indexing better. Formatting the query with uppercase keywords and line breaks enhances maintainability.

Issues:
1. [Medium] Repetitive OR conditions — harder to read and less efficient — replace with IN clause.
2. [Low] Lack of formatting — reduces readability and maintainability — format keywords uppercase and clauses on separate lines.
3. [Low] SELECT * usage — may fetch unnecessary columns impacting performance — specify needed columns explicitly.

Quick Fixes:
- Replace OR conditions with IN (status IN ('paid', 'captured', 'settled')).
- Format SQL keywords in uppercase and place each clause on its own line.
- Replace SELECT * with explicit column names if known.

Updated Code:
SELECT *
FROM orders
WHERE status IN ('paid', 'captured', 'settled');

Example Walkthrough 5: Safer Rust Naming

Input snippet:

fn run(v: Vec<i32>) -> i32 {
    let mut r = 0;
    for i in v {
        if i > 10 { r += i }
    }
    r
}

Output:

Summary:
The main issues are suboptimal readability and missed performance improvements by not using iterator methods. The quick win is to replace the explicit for-loop with iterator combinators like filter and sum for clearer, more idiomatic, and potentially more efficient code.

Issues:
1. [Medium] Uses explicit for-loop with mutation — less idiomatic and harder to read — use iterator methods like filter and sum.
2. [Low] Consumes vector by value — may be unintended if vector is needed later — consider iterating by reference if ownership is not required.
3. [Low] Variable naming is non-descriptive (`r`) — reduces maintainability — use descriptive names like `sum`.

Quick Fixes:
- Replace the for-loop with `v.iter().filter(|&&i| i > 10).sum()`.
- Iterate over references if the vector should not be consumed.
- Rename `r` to `sum` for clarity.

Updated Code:
fn run(v: Vec<i32>) -> i32 {
    v.iter().filter(|&&i| i > 10).sum()
}

Tips For Teams Adopting This Tool

  • Add a pre push habit. Run the review before you open a pull request
  • Encourage small diffs. Merge more often with fewer lines changed
  • Celebrate readable code in reviews. People copy what gets praise
  • Keep a shared glossary of names for domain terms
  • Use the tool to train new hires on your preferred patterns

Developer’s Note

We hope our AI-powered code reviewer & refactoring tool helped streamline your task. At CodeForGeek, we are constantly developing intelligent tools to boost developer productivity.

  • Explore: Check our full suite of free developer tools here.
  • Improve: Have feedback or a feature request? Email us at [email protected]. We value user suggestions and act on them.
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Aditya Gupta
Aditya Gupta
Articles: 413
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