28 best Python Form Validation libraries in 2025

Python is an indispensable tool for many programmers. With it, you can do away with all the repetitive and tedious work involved with other scripting languages.

For a technical process like form validation, with Python, you can ensure that the input text is in the correct format (including both after submitting and inline validation). Hence, when you build an application that accepts user input, you can verify that the data that enters your application is valid, consistent, and secure with various open-source Python libraries.

Here we list down some of those libraries which are useful for form validation. Say, with pydantic, you can define custom data types, parse input data, and then validate it. Using type hints, the library can even coerce input data to the declared types and accumulate errors using ValidationError. pydantic is also easily discoverable given how well it has been documented. Another application, Django-crispy-forms helps you manage Django forms by allowing you to adjust their properties (say, CSS classes, send button, etc.) on the backend. This means you no longer have to rewrite anything in the template. We also have Formspree, which is a backend, API, and email service for HTML and JavaScript forms. It is secure with a honeypot to prevent spam and is the simplest way to embed customized order forms, “Contact Us” forms, and dialogue boxes meant to capture email.

pydantic:  

• It is a popular Python library for data validation and parsing.  
• It allows you to define the expected types of data for each field in your form.   
• It ensures that the data you receive conforms to your expectations.  

marshmallow:  

• It is a library used for data serialization and deserialization. It can also handle form validation.  
• It provides a way to define data schemas and confirm input data against those schemas.  
• Offers features for input validation, data normalization, and data serialization/deserialization. 

django-crispy-forms:  

• It is a popular Python library. It helps in form rendering and form management in Django web applications.   
• It provides a cleaner and more elegant way to render forms in HTML.  
• It helps ensure that forms in Django app. It has a consistent and professional appearance. 

connexion:  

• This can be crucial for various reasons, particularly when developing web applications.   
• It allows you to enforce specific business rules and logic.  
• It ensures that data conforms to the requirements of your application.

formspree:  

• It allows you to create and manage web forms for your website.  
• It takes security and provides features to help protect against spam and abuse. It includes CAPTCHA support.  
• It allows you to collect and store data from your forms.  

sqlparse:  

• It provides parsing and formatting capabilities for SQL statements.  
• It can format SQL queries to make them more readable.  
• It helps in analyzing the structure of SQL queries.  

cerberus:  

• It is a lightweight and extensible data validation library for Python.  
• It confirms data structures, including data submitted via forms.  
• It allows you to define validation rules using a simple and flexible schema.

schema:  

• It defines the structure and constraints of the data that your forms should accept.  
• It helps in detecting and reporting errors in user-submitted data.  
• This makes it easier to maintain and update your form validation rules.  

SublimePrettyJson:  

• It is a Sublime Text plugin designed to format and prettify JSON data.  
• It makes JSON data more human-readable. It does so by organizing it in a structured and indented format.  
• It can improve a developer's productivity by automating the formatting process.  

django-widget-tweaks:  

• It simplifies the rendering and customization of form widgets.  
• It allows you to customize the rendering of form widgets in your HTML templates.  
• It simplifies the template code required to render form elements. This makes it more readable and maintainable.  

pandera:  

• It helps ensure the quality and integrity of your data.  
• Ensure data by specifying validation rules and constraints on your datasets. 
• Use it alongside other data libraries and tools like pandas.

wtforms:  

• WTForms is a form validation library used for Flask web applications.  
• It provides a simple and flexible way to define forms as Python classes and confirm them.  
• Supports various field types and allows you to define custom validation functions.  
• Offers CSRF protection and integration with popular web frameworks.

ohmyform:  

• It simplifies the process of validating user input in web applications.  
• It aims to be a lightweight and straightforward library.  
• It allows you to define your custom validation rules and error messages.  

django-simple-captcha:  

• It is a third-party library for Django, a popular Python web framework.  
• It provides a simple and effective way to add CAPTCHA protection to your web forms.  
• It is customizable and integrated into your Django forms.  

django-phonenumber-field:  

• It is a useful library in Python for form validation.   
• It is especially used when dealing with phone numbers in Django web applications.  
• It is a valuable library for managing and validating phone numbers in Django apps.  

brigadier:  

• It is a Python library. The brigadier has no bugs or vulnerabilities.  
• It has a Permissive License, and it has a medium support.  
• It fetches and installs Boot Camp ESDs with ease.  

django-money:  

• It helps to manage money-related fields and calculations in Django apps.  
• It provides tools for handling currency and monetary values.  
• It supports Decimal-based arithmetic, which is crucial for accurate financial calculations.  

django-smart-selects:  

• It provides an enhancement to form validation.  
• It enables you to create dynamic select fields in your forms.  
• It is open-source and has an active community.

awesome-fraud-detection-papers:  

• It is a curated list of research papers and resources related to fraud detection.  
• In the context of Python, form validation libraries would depend on the specific use case.  
• They help prevent common issues. Those issues are SQL injection, cross-site scripting, and other security vulnerabilities.

django-recaptcha:  

• It is an important library for form validation in Python, particularly in Django web apps.  
• It helps protect your web forms from automated bots and spam by adding a CAPTCHA challenge.  
• It works with Django forms, making it easy to integrate and use in your web applications.  

data-validation:  

• It is a crucial aspect of form validation in Python libraries.  
• It helps protect your application from various security vulnerabilities. Those are such as SQL injection and XSS attacks.  
• Validating user input at the form level provides a better user experience.   

pyforms:  

• It is a Python framework for developing desktop applications and GUIs.  
• It simplifies the creation of GUI applications by providing a high-level, Pythonic interface.  
• It works on many platforms, including Windows, macOS, and Linux.

enforce:  

• It contains pre-written code, functions, and modules.  
• Using libraries can speed up development, as you don't need to reinvent the wheel for common tasks.  
• It can help standardize practices and promote best practices in software development.

UhOh365:  

• It is a Python library used in Utilities applications.  
• UhOh365 has a low active ecosystem.  
• A script that can see if an email address is valid in Office365. 

ystockquote:  

• ystockquote is a Python library used in Web Site, Business applications.  
• You can install using 'pip install ystockquote' or download it from GitHub, PyPI.  
• It fetches stock quote data from Yahoo Finance. 

django-formtools:  

• It includes a Form Wizard, which is a powerful tool for handling multi-step forms.  
• It provides more control over the form-handling process.  
• The above process enables custom logic to insert between form steps.  

validate_email:  

• It helps in form validation libraries to ensure that an email address entered by a user is valid.  
• Validating email addresses helps maintain the integrity of the data collected through forms.  
• It is a crucial step in preventing common security vulnerabilities. 

typesystem:  

• Type systems help ensure that data is in the expected format and adheres to specific data types.  
• Type hints make the code more readable.  
• It can be especially beneficial when working on a team or maintaining code over time.  

FAQ 

1: What is a Python form validation library?  

A Python form validation library is a tool that helps developers confirm user input in web forms. It ensures that the data entered by users to specified rules and constraints. Implementing validation rules and constraints actively prevents the application from processing malicious data. 

2: Why should I use a form validation library in Python?  

Using a form validation library is important to maintain data integrity and security. It helps prevent common issues. Those are like data type mismatches, SQL injection, and XSS attacks. This ensures that user input is safe and valid.  

3: Which Python form validation libraries are used?  

There are several popular Python form validation libraries, including:  

• WTForms: A used library for form validation and rendering in Flask. It is also used in other Python web frameworks.  
• Django Forms: Built-in form handling in the Django web framework.  
• Marshmallow: It is a library for object serialization and deserialization. It is often used for form validation in web APIs.  
• FormEncode: A library for validating and converting form data.  
• Validictory: A lightweight JSON validation library that helps with form validation.  

4: How do I install a Python form validation library?  

You can usually install Python form validation libraries using package managers like pip. For example, you can install WTForms with the command pip install WTForms.  

5: How do I use a Python form validation library in my web application?  

Each library has its own documentation and usage guidelines. Generally, you'll define a form class with fields and validation rules. Then render the form in your template, and then confirm user input using the library's methods.