Got it, let's tackle this EXE bloat issue—109MB is way over your platform's limit, but there are proven ways to trim it down to size. Here's what you can do, ordered from easiest to more involved:

1. Optimize Your PyInstaller Build with Key Flags #

Start by tweaking PyInstaller's default settings to cut out unnecessary bloat right away. Run your build command with these flags:

• --noconsole: If your browser is a GUI app (no command line window needed), this strips out console-related code.
• --clean: Clears PyInstaller's cached build files to avoid including old, unused dependencies.
• --strip: Removes debug symbols from the final EXE (safe for release builds).
• --exclude-module: Explicitly leave out any Python modules you don't use (e.g., tkinter, matplotlib if you never imported them).

Example command:

pyinstaller --onefile --noconsole --clean --strip --exclude-module tkinter --exclude-module pandas your_browser.py

2. Use a Minimal Virtual Environment #

Chances are your global Python environment has dozens of unused libraries (like data science packages, testing frameworks) that PyInstaller is accidentally bundling. Fix this by creating a fresh virtual environment with only the dependencies your browser needs:

• Create a new venv: python -m venv browser_env
• Activate it (Windows: browser_env\Scripts\activate, macOS/Linux: source browser_env/bin/activate)
• Install only required packages (e.g., pip install PyQt6 PyQt6-WebEngine requests)
• Run PyInstaller from this clean environment—this alone can cut your EXE size in half.

3. Compress the EXE with UPX #

UPX is a free, open-source tool that compresses executable files without losing functionality. PyInstaller integrates with it directly:

• Download UPX (just extract the executable, no installation needed)
• Add the --upx-dir flag to your PyInstaller command, pointing to where you extracted UPX:

pyinstaller --onefile --noconsole --upx-dir "C:\path\to\upx-folder" your_browser.py

Note: Some antivirus tools might flag UPX-compressed files as suspicious, but most platforms accept them for legitimate apps.

4. Trim Unused Code and Dependencies #

Dig into your browser's code to remove dead weight:

• Replace wildcard imports (from PyQt6 import *) with specific imports (from PyQt6.QtWebEngineWidgets import QWebEngineView) to only bundle the parts of libraries you actually use.
• Swap heavy dependencies for lighter alternatives if possible (e.g., use urllib instead of requests if your browser's network needs are simple).
• Delete any commented-out code or unused functions—PyInstaller might still trace unused imports if they're present.

5. Switch to a Single-Directory Build (Instead of OneFile) #

The --onefile flag bundles everything into a single EXE, but it adds overhead from self-extraction logic. Try building a single directory instead:

• Remove --onefile from your PyInstaller command—this creates a folder with your EXE + all dependencies.
• Compress the entire folder using 7-Zip (set compression level to "Ultra") or WinRAR. You can even create a self-extracting archive if the platform prefers a single file.
• This approach often results in a compressed package well under 25MB, since individual files compress better than a single self-extracting EXE.

6. Try Alternative Packagers: Nuitka or cx_Freeze #

If PyInstaller still isn't giving you the size you need, switch to tools that compile Python code to native binaries instead of just bundling it:

• Nuitka: Converts Python code to C, then compiles it to a native executable. It often produces smaller, faster builds. Example command:

  nuitka --standalone --windows-disable-console --include-module PyQt6.QtWebEngineWidgets your_browser.py
  

• cx_Freeze: Another bundler with more granular control over which files to include. It can sometimes produce smaller builds than PyInstaller for GUI apps.

Start with steps 1 and 2—those are the quickest wins. If you still need more compression, add UPX or try a single-directory build. You should easily get under 25MB with a combination of these techniques.

内容的提问来源于stack exchange，提问作者Sreehari521