Code
Fix bugs faster with AI
Paste in your broken code and get a corrected version with an explanation of what was wrong.
For the best results: Paste your full code and the exact error message. Include the language and what you expected to happen vs. what actually did.
What is Bug Fixer?
Bug Fixer is a free AI coding assistant that takes broken code and returns a corrected version with an explanation of what went wrong. Each request is handed to a code-specialized model chosen for the task, returning working code, bug fixes, and explanations in any programming language in seconds. You paste and go, with no login and nothing to install, and the code you share is not retained once the session ends.
- ✦Paste code and go, no login, nothing to install
- ✦Code-specialized models are selected per request automatically
- ✦Your code is not retained after the session ends
Models: It routes across strong coding models including Llama, Gemini and Mistral families, picking the best available one per request. The exact model used is shown after every response.
See it in action
A Python developer notices a shopping cart that keeps items from a previous customer even after the page is reloaded.
What you type
def add_item(item, cart=[]): cart.append(item) return cart
What you get
def add_item(item, cart=None): if cart is None: cart = [] cart.append(item) return cart What went wrong: the default [] is created once when the function is defined, not on each call, so every call that omits cart shares and mutates the same list. Using None as the sentinel and building a fresh list inside fixes it.
Tip: The mutable-default-argument trap only bites when the caller leaves the argument out, which is exactly why it survives most quick tests. Paste the calling code too so the fixer can confirm the shared-state path is the one you actually hit.
Use cases
What people use it for
Work out why a form submits twice when the click handler looks fine to you.
Fix a null reference crash at 11pm when no teammate is awake to ask.
Trace an off-by-one error that quietly corrupts the last row of your output.
Who uses Bug Fixer?
Bootcamp students
pasting a failing assignment and learning why it broke, so the next similar bug is one they can fix themselves
Weekend hobbyists
unsticking a personal project in a language they half-know, without posting to a forum and waiting a day for a reply
Full-stack developers
getting a second opinion on a subtle logic bug they have stared at too long to see clearly
How it works
- 1Paste your code or describe what you need built.
- 2A code-specialized model writes, fixes, or explains it.
- 3Copy the code out, or ask follow-ups to iterate on it.
Tips for the best results
- Paste the exact error message and the line it points to alongside the code, since the traceback usually names the failing call directly.
- Say what the code is meant to do and what it does instead; a bug with no exception can only be found against your intended behavior.
- Include enough surrounding context, such as the function that calls the broken one and the data being passed in, so the fix accounts for how the code is actually used.
- When you get the correction, read the explanation before pasting it back, so you can spot the same mistake yourself next time.
- If the fix does not work, reply with the new error rather than starting over; each round narrows down what is really going wrong.
FAQ
Frequently asked questions
What should I paste along with the broken code?
Three things make the difference: the exact error message or wrong output, what you expected instead, and the input that triggers it. Code alone forces the AI to guess which behavior is the bug. With those details you'll usually get a targeted fix rather than a list of maybes.
My bug spans several files, how do I handle that?
Include the relevant sections from each file in one message, with a line noting how they connect, this function calls that handler, and so on. Trim what's clearly unrelated so the signal stays strong. If you genuinely can't isolate it, describe the architecture and ask what to check first.
Will it rewrite everything, or just fix what's broken?
The default is a corrected version with the fix explained, but AI sometimes tidies more than you asked. If you want your structure and style left alone, say 'change only what's necessary to fix the bug', then diff the result against your original before committing it.
What if the suggested fix doesn't work?
Paste the new error or behavior back in the same session, context carries while the tab stays open, so it builds on what it already knows. Real debugging is iterative, and second or third attempts, informed by what failed, are often where the actual cause finally surfaces.
Can it find bugs when there's no error message at all?
Silent logic bugs (wrong totals, missing rows, nothing crashing) are fair game. Describe what the code should produce and what it actually produces, with a concrete example of each. The explanation you get back matters as much as the fix, because it tells you whether the diagnosis is right.
Is this bug fixer free and does it need an account?
It is free and needs no account, sign-up or payment. Paste broken code, get a corrected version and an explanation, and repeat as often as you need. Nothing is capped behind a login. Because there is no account, keep genuine secrets out of what you paste and swap in placeholder values instead.
Which programming languages can it debug?
All the mainstream ones, including JavaScript, TypeScript, Python, Java, C#, C++, Go, Ruby, PHP, Rust, SQL and shell scripts, plus their common frameworks. Name the language and framework in your message if it is not obvious from the code, so the fix follows that ecosystem conventions rather than a generic guess.
Can it fix logic bugs, not just crashes and syntax errors?
Yes, if you tell it what should happen. For a crash the error points the way, but a logic bug produces wrong output with no complaint, so describe the expected result versus what you actually get. With that comparison it can trace the faulty branch, off-by-one or condition and correct it.
What are the usage limits?
Code tools are text tools, so they are unmetered during the current free launch phase, iterate on a bug or generate as many drafts as the work needs. A short per-minute limit guards against scripted abuse only. Paid plans with higher limits and priority model access are coming soon.
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