The unchanged sample passes syntax checking. Removing the function colon produces a report identifying the affected line and column.
CHECK CODE · FREE PYTHON TOOL
Python Syntax Checker Online
Check Python source for syntax errors and receive a focused explanation with the exact line, column and offending source text.
Free to useNo sign-upRuns in your browser
PyPython Syntax CheckerReal Python in an isolated browser worker
Python runtime preparing…
Your result will appear here.
A WORKED TASK
Separate a syntax error from a runtime error
The checker parses Python without running the program. Remove the colon after def greet(name) in the sample and check it. Restore the colon and try again. This helps you practise finding a grammar problem before introducing input, files or program execution.
Passing the syntax check does not prove that names exist, imports are installed, values have the right type or the algorithm is correct. The source is parsed, not executed.
What to check
- A missing colon, unmatched bracket or indentation error can stop parsing.
- The reported position may be after the real mistake; inspect the preceding line too.
- A syntactically valid print(unknown_name) can still fail when run. Use the runner for that second check.
TESTED & REVIEWED
Know what this tool does—and where to double-check
- Reviewed by
- HTML Online Viewer project
- Last reviewed
- Processing
- Code and supported files are processed in this browser tab. Runtime tools download Python WebAssembly, but do not intentionally upload your source.
- Important limitation
- The browser runtime is intentionally isolated and may not include every desktop package, system command or network feature. Verify production programs in their target Python environment.
EXAMPLE INPUT
Start small, then use your own data
Python source
def greet(name):
message = f"Hello, {name}!"
return message
print(greet("Kampala"))The unchanged sample passes syntax checking. Removing the function colon produces a report identifying the affected line and column.
COMMON QUESTIONS
Python Syntax Checker FAQ
Does this upload my code or files?
No. Processing happens locally in your browser. Runtime tools download Python itself, but your source is not sent to our server.
Why can the first Python run take longer?
The browser downloads and starts the Python WebAssembly runtime. Later runs in the same tab are normally much faster.
Can I stop a program that takes too long?
Yes. Runtime tools show a Stop button while Python is working. Stopping terminates the isolated worker and a clean runtime starts when needed.