Why would I need to view the AST?

It's essential when building developer tools. Writing a custom lint rule, a formatter, a code transformation, or an obfuscator all require reading and often rewriting the AST, and viewing it is how you learn which node types and fields you need to target. It's also one of the clearest ways to understand Python's grammar.

How do I view a Python AST online?

Paste your Python code into the AST Viewer and it parses the script with Python's ast module, rendering the full tree so you can inspect every node — functions, loops, imports, and expressions — exactly as the interpreter sees them. No installation is required.

How does this relate to Python's built-in ast module?

It's an interactive front end to the same thing. In code you'd call ast.parse(source) to get the tree and use ast.NodeVisitor or ast.NodeTransformer to traverse or rewrite it. This viewer shows you that parsed structure instantly, which is useful for prototyping a visitor or checking what a snippet compiles to before writing traversal code.

Code Module

Python AST Viewer

Visualize and explore the Abstract Syntax Tree of your scripts.

Why use this tool?

Use the AST Viewer to visually inspect the Abstract Syntax Tree of any Python script. It's the ultimate debugging and educational tool for developers building compilers, linters, or static analyzers.

Python Source Code

def calculate_sum(a, b):
    return a + b

x = calculate_sum(5, 10)

Abstract Syntax Tree

# The AST will appear here after parsing — switch between the JSON tree and Python's native ast.dump().

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Tool facts

Supported Python: Python 3.x (CPython ast via Pyodide)
Input limit: Limited only by your device
Last reviewed: 2026-08-25

What it can't do

•Execute your code — it parses source into an abstract syntax tree only.
•Parse code that has syntax errors (fix them first).

About Python AST Viewer

The Python AST Viewer parses your code into its Abstract Syntax Tree and displays the node hierarchy the interpreter actually works with. It's built for developers learning compiler and language internals, and for anyone building Python tooling — linters, formatters, code-mods, static analyzers, or obfuscators — where reading and transforming the AST is the core technique.

When Python runs your code, it first tokenizes the source, then parses those tokens into an AST: a tree in which every construct — a module, function definition, loop, if-statement, function call, or literal — becomes a typed node with named fields and child nodes. This tree is the structured, unambiguous form of your program, which is why real tooling operates on it instead of manipulating raw text with regular expressions.

Seeing the tree makes abstract behavior concrete. You can watch how operator precedence nests a BinOp, how a list comprehension expands into its component nodes, how default arguments and decorators attach to a FunctionDef, or how an assignment splits into targets and a value. It's one of the fastest ways to build an accurate mental model of Python's grammar.

The same structure is available in Python itself through the built-in ast module: ast.parse(source) returns the tree, ast.dump() prints it, ast.walk() and ast.NodeVisitor let you traverse it, and ast.NodeTransformer lets you rewrite it. This viewer is essentially an interactive, no-setup front end to ast.parse — handy for prototyping a visitor or confirming what a snippet compiles to before you write the traversal code.

AST generation runs client-side in your browser, so you get an immediate result the moment you paste your code.

Want the flow instead of the tree? Turn the same code into a diagram with the Python code-to-flowchart generator — it reads this AST to draw if/loop/match/try branches and a control-flow graph.

Frequently Asked Questions

An AST is a tree representation of your program's syntactic structure. Each node denotes a construct — a function, loop, call, assignment, or literal — with typed fields and children. It's the structured form the interpreter uses after parsing, and the form that linters, formatters, and other tools operate on.

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