A stack trace tells you where the program stopped, not always why. The AI Bug Fixer reads the code and the error together and explains the root cause in plain words, so you fix the problem, not the symptom.
You paste everything in one field, the code, the full error message and what should happen instead. The answer comes in four parts, a diagnosis that ranks the likely causes, the corrected code with each changed line marked, why the fix works, and how to keep the bug from coming back.
The tool changes only what is needed, so the diff stays small. It is part of the Developer tools family. To understand unfamiliar code before touching it, start with the Code Explainer.
What you get
- A diagnosis of the root cause in plain language, with the possible causes ranked by likelihood when the error is ambiguous
- The corrected code in a fenced code block tagged with the language, changed lines marked with a short comment
- Two to four bullet points on why the fix works
- One or two prevention tips, or a test that would catch the bug in the future
What you fill in
- Code and error required
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Include the language and version, the full error or stack trace and the expected result. Remove passwords, API keys and personal data before pasting.
How to use it, step by step
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Open Bug Fixer in the workspace
It is in the Developer tools family. Everything goes in one field, Code and error.
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Paste the code, the error and the expected result
Add the language and version, the full error or stack trace, and one line on what should happen. Remove passwords, API keys and personal data first.
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Choose the output language and generate
The explanations follow the language you pick, while code, identifiers and error messages stay exactly as they are.
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Review the diff before you commit
Compare the marked lines with your original, run the tests, and add the suggested test to your suite if it fits.
Example, input and output
Input
- issue_description
- Python 3.12. Each call should return a list with one item, but the list keeps growing. def add_tag(tag, tags=[]): tags.append(tag) return tags print(add_tag("a")) print(add_tag("b")) # expected ['b'], got ['a', 'b']
Output
The default value `tags=[]` is created once, when the function is defined, not on every call. Each call that omits `tags` appends to the same list, so items from earlier calls remain.
## Fix
```python
def add_tag(tag, tags=None):
if tags is None: # changed: create a new list on each call
tags = []
tags.append(tag)
return tags
```
## Why it works
- `None` is immutable, so it is safe as a default value.
- A new list is created inside the function on every call without `tags`.
## Prevention
- Never use a list, dict or set as a default argument.
Illustrative example written by the editorial team to show the expected format.
Tips for better results
- Paste the full stack trace, not just the last line. The frames above the error often point to the real cause.
- Say what the code should do. The tool can only spot a logic bug if it knows the expected result.
- Include the versions of the language and of key libraries, since many errors only appear in a specific release.
Who uses it, and for what
Developers stuck on a cryptic error
Paste the failing function and the trace to get a ranked list of causes instead of searching forums one result at a time.
Students learning to debug
The diagnosis and the why-it-works points explain the mistake, so the lesson sticks.
Reviewers checking a suspicious change
Paste a snippet that behaves oddly and use the marked lines as a starting point for a review comment.
Freelancers maintaining old code
Get a first diagnosis on legacy scripts in a language you use less often, then verify it against the docs.
Limits and good practice
- It does not run your code. The fix is reasoned from what you paste, so test it before merging.
- It sees only the field content, not your repository, database or environment variables.
- When it is unsure whether a function exists in your version, it says so instead of guessing. Check those points in the official documentation.
- Each generation uses credits from your plan, see pricing or create an account.
Frequently asked questions
Can AI fix bugs in my code?
It can find the likely cause and propose a corrected version for errors you can reproduce in a snippet. It does not execute the code, so run your tests and check the changed lines before you merge.
Which programming languages does the Bug Fixer support?
There is no fixed list. You write the language and version in the field, and the fix comes back in a code block tagged with that language, whether it is Python, JavaScript, PHP, Java, Go or SQL.
What should I paste for the best diagnosis?
The smallest piece of code that still fails, the complete error message or stack trace, the language and version, and one sentence on the result you expected. Without the expected result, a logic bug that throws no error is hard to spot.
What happens if I paste an API key by mistake?
The tool is instructed not to repeat passwords, keys or personal data. It replaces them with placeholders and reminds you to rotate any exposed key. Still, remove secrets before pasting and rotate any key that has left your machine.
Will it rewrite my whole function?
No. It changes only what is needed to fix the bug and marks each changed line with a short comment, so the diff stays easy to review. If the code needs a broader refactor, the prevention tips can say so.
Try it in your workspace
Start free, no credit card needed. When you need more, one suite grows with you, from Lite to Agency.
Sign in or create a free account, the tool opens in your workspace.