How to Make Your Own Python Library

You will need Python 3, a code editor such as IDLE, and a free PyPI account. If pip is unavailable, use the pip troubleshooting guide.

Step 1: Defining the functions

Open IDLE and create a new Python file. Define the functions you want your library to provide. The function below is only an example—you should replace it with the functions you want in your own library.

Example function

def listrange(start, stop, step):
    return list(range(start, stop, step))

In this example, listrange creates a list of numbers. Put any values your own function needs inside the parentheses as comma-separated arguments.

Step 2: Testing your library locally

Save the file as mylibrary.py in Downloads. Create another script in the same folder and test it:

import mylibrary

numbers = mylibrary.listrange(1, 10, 2)
print(numbers)

The output (if you used the example) should be [1, 3, 5, 7, 9]. If it is different from what you expected for your functions, reopen mylibrary.py and debug it before packaging.

Step 3: Packaging your library

Upload your working .py file below and fill in the package details. The tool creates a standard Python project ZIP containing your code, pyproject.toml, README, build instructions, and a basic import test.

Your Python file never leaves this device. The package is assembled locally in your browser.

Choose a .py file or drag it here One Python file, up to 1 MB

No file selected yet.

Library name The public pip name. It must be unique on PyPI. To check, type pip3 install library-name in macOS Terminal, or pip install library-name in Windows CMD or PowerShell.

Version Start with 0.1.0. Every later upload needs a new version.

Author name

Author email

Purpose and description

Public functions Detected functions appear here automatically. Separate names with commas.

Minimum Python version

License

Not specified No license is granted. Other people generally cannot copy, modify, or redistribute the code without permission. MIT Allows private, commercial, and modified use. Redistributions must keep the copyright and license notice. No warranty. Apache 2.0 Permissive commercial and modified use with a patent grant. Keep notices, identify changes, and include the license. No warranty. BSD 3-Clause Allows private, commercial, and modified use. Keep copyright notices and do not use contributor names for endorsement. No warranty. GNU GPL v3 Allows use and modification, but redistributed versions and derivatives must remain GPL v3 and provide source code. No warranty.

Hover over or focus a license to read its brief terms. These summaries are not legal advice.

Homepage or source URL

Open the downloaded ZIP and move the generated project folder to Downloads. Your original code will be inside src/your_library/__init__.py. The pip name may contain hyphens, while the import name uses underscores.

Step 4: Submitting to PyPI

Register or sign in at PyPI, then verify your email using the link PyPI sends to your inbox. Before uploading, search PyPI to make sure your chosen library name is available.

Create a PyPI API token →

Name the token after your device, such as “John’s MacBook Air.” For the first release of a new project, create an account-scoped token. After publishing, replace it with a token scoped only to that project.

Copy the complete token beginning with pypi- and keep it private. If it is ever shared or shown in a screenshot, revoke it immediately and create another one.

Open Terminal, PowerShell, or Command Prompt, enter the generated project folder, and run the commands for your system. Replace your-library-project with the folder name from the ZIP.

macOS or Linux Terminal

cd ~/Downloads/your-library-project
python3 -m venv .venv
source .venv/bin/activate
pip3 install --upgrade build twine
python3 -m build
python3 -m twine check dist/*
python3 -m twine upload --username __token__ dist/*

Windows PowerShell

cd "$HOME\Downloads\your-library-project"
py -m venv .venv
.venv\Scripts\Activate.ps1
py -m pip install --upgrade build twine
py -m build
py -m twine check dist/*
py -m twine upload --username __token__ dist/*

Windows Command Prompt

cd %USERPROFILE%\Downloads\your-library-project
py -m venv .venv
.venv\Scripts\activate.bat
py -m pip install --upgrade build twine
py -m build
py -m twine check dist/*
py -m twine upload --username __token__ dist/*

When Twine asks for the password, paste only the complete API token beginning with pypi-. The token will remain invisible while you paste. Do not add __token__ before or after it—the command already supplied that username.

A published PyPI version cannot be replaced. If you need to upload again, change the version in pyproject.toml, rebuild, and upload the new files. Or fill in the previous form again, but increment the version number, then build and upload the newly generated package.

Install your library on another device

After PyPI confirms the upload, install your package on any compatible computer:

macOS Terminal

pip3 install your-library-name

Windows Command Prompt or PowerShell

pip install your-library-name

Then import it in Python:

import your_library_name

Use pip3 on macOS and pip on Windows.