JBrowser Source Docs
You are reading the documentation for JBrowser 1.5.3. The newest release is 1.5.4. Go to the latest documentation

Setting up a development environment

JBrowser runs straight from its source code: there is no compile step. Setting up takes three commands and a few minutes, most of it downloading Qt WebEngine (about 400 MB).

Requirements#

What Why Get it
Windows 10 or 11, 64-bit JBrowser uses Windows APIs directly (DWM backdrops, DPAPI, the window frame)
Python 3.14 or newer, 64-bit, with the py launcher The code uses Python 3.14 python.org or winget install Python.Python.3.14
Git To clone the repository Git for Windows, or GitHub Desktop, which bundles it
Inno Setup 6 (optional) Only to build the installer winget install JRSoftware.InnoSetup
GitHub CLI (optional) Only to publish releases winget install GitHub.cli, then gh auth login

Other operating systems are not supported: jbrowser/platform/win.py calls the Win32 API through ctypes, and the window relies on Windows 11 system backdrops.

Get the code and the packages#

git clone https://github.com/The-JBrowser-Team/JBrowser.git
cd JBrowser
py -3.14 tools\update_deps.py

tools/update_deps.py does everything else:

  1. creates .venv with the Python that runs it, if it doesn't exist yet;
  2. upgrades pip and installs requirements-build.txt: the app's packages from requirements.txt plus PyInstaller and pyflakes;
  3. imports every module of the jbrowser package and every Qt module the app uses, so a broken package shows up now rather than when someone opens a dialog;
  4. runs pyflakes over jbrowser, tools and main.py.

Run it again at any time to update every package to its newest version. It prints the installed versions at the end.

Run JBrowser#

.\.venv\Scripts\python.exe main.py                                  # your normal profile
.\.venv\Scripts\python.exe main.py --profile-dir "$env:TEMP\jb-dev"  # a throw-away profile

python -m jbrowser works too. Use a throw-away --profile-dir while developing: everything JBrowser stores then goes into that folder, it can run next to your everyday JBrowser, and deleting the folder resets it. See the command line for every option.

On a new profile the first-run welcome appears. Set JBROWSER_SKIP_WELCOME=1 to skip it, and JBROWSER_SKIP_UPDATES=1 so a development copy never asks GitHub for updates:

$env:JBROWSER_SKIP_WELCOME = "1"; $env:JBROWSER_SKIP_UPDATES = "1"
.\.venv\Scripts\python.exe main.py --profile-dir "$env:TEMP\jb-dev" --debug

--debug also prints the log to the console.

Editor#

Any editor works. Point it at the interpreter in .venv\Scripts\python.exe so imports resolve. The repository's .editorconfig sets UTF-8, LF line endings (CRLF for .ps1 and .iss files), four-space indentation and a final newline; most editors read it automatically. Lines are kept under about 120 characters.

In VS Code, the Python extension picks up .venv by itself. A launch configuration that runs main.py with --profile-dir gives you breakpoints in the UI code.

Next steps#