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Guide

Getting Started

Drag and drop a .wasm file onto the drop zone on the main page, or click to browse your files. You can also click Try Sample to load a built-in example module.

The 7 Tabs

• Overview — Summary cards showing version, file size, section count, function count, memory, exports, and producer information.
• Types — Function type signatures (parameter and return types).
• Functions — All functions (imported + defined) with name, signature, kind, code size, and local variables. Searchable.
• Imports & Exports — Imports grouped by module, exports listed with kind icons.
• Memory & Data — Memory pages, tables, globals, and data segment summary.
• Custom Sections — List of custom sections with parsed content for known types (name, producers).
• Size Analysis — ECharts visualizations: pie chart of section categories, bar chart of largest functions, treemap of section sizes.

Understanding WASM Structure

A WebAssembly module starts with a magic number (\0asm) and version, followed by sections. Each section has a 1-byte ID and LEB128-encoded size. The function index space starts with imported functions, then defined functions.

Tips

• Use the Functions tab search to find specific functions in large modules.
• The Size Analysis tab helps identify bloated functions or large data sections.
• Check Custom Sections for debug names and producer tool information.

Contact

Feedback? nullkit.dev@outlook.com