File or paste workflow
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JavaScript Utilities
JavaScript Execution Trace Sandbox
Run JavaScript in an isolated sandbox and capture execution trace with function calls, arguments, return values, and runtime errors. Useful for debugging opaque snippets safely.
JavaScript for sandbox execution
Execution trace log
Why use this tool
Readable formatting
Transforms compressed JavaScript into structured code with normal indentation and line breaks.
Identifier expansion
Optionally renames very short symbols like a, b, c into clearer contextual variable names.
Diff-friendly output
Generated code is easier to review in pull requests and debugging sessions.
In-browser privacy
Processing runs locally in your browser without sending code to external servers.
Instant export
Copy the formatted result, export unpacked modules as ZIP, or download recovered files from source maps.
JavaScript Execution Trace Sandbox: capture function calls, arguments, and returns
Execution Trace mode runs code in an isolated sandbox and records runtime events, including calls, arguments, return values, and errors.
It is effective for analyzing unknown snippets, reproducing side effects, and validating behavior before integrating code into real projects.
Trace logs provide chronological visibility into control flow, which speeds up debugging of async logic and hidden branching paths.
You can download trace output for documentation, incident reports, and team reviews where exact runtime evidence is required.
This mode complements decompression and source maps by adding execution-level insight on top of static code recovery.
JS Decompressor FAQ
Does this restore the exact original source code?
No. It restores readable formatting and can improve naming, but minification is not fully reversible to the exact original source.
Can I use it for obfuscated JavaScript too?
It can improve readability for partially obfuscated code, but heavy obfuscation may still require manual analysis.
Is the code sent to your server?
No. Decompression runs in the browser, so your code stays on your machine.
Can I download the result?
Yes. After decompression, download the output as a .js file or copy it directly to clipboard.