Open-source alternatives to Heml

Email-Boilerplate is an HTML email template framework and design system providing a foundational code structure for developing newsletters and transactional emails. It serves as a cross-client email layout library designed to ensure consistent rendering across diverse desktop and mobile email applications. The project utilizes a table-based layout library and reusable code patterns to maintain structural integrity within restrictive email rendering engines. It employs a responsive design system that combines fluid hybrid scaling and semantic markup normalization to resolve common rendering in

This project is a responsive email design framework providing a collection of HTML templates and boilerplates specifically for transactional messages. It serves as a toolkit for building and validating emails that maintain a consistent appearance across diverse email clients and devices. The framework includes pre-made layouts for common business communications, such as billing receipts, account warnings, and email verification requests. It utilizes a CSS inlining tool to convert external stylesheets into inline element styles, ensuring visual consistency across different providers. The syst

Cerberus is an HTML email template framework providing a collection of tested markup patterns and architectural kits. It is designed to create responsive email newsletters that render consistently across diverse software clients. The project features a responsive email layout system using fluid and hybrid table-based structures, alongside a cross-client CSS kit that employs conditional markup to maintain visual consistency in legacy clients. It includes specific methodologies for implementing dark mode by adjusting colors and images based on operating system theme preferences. The framework

React Email Editor is a drag-and-drop visual builder for creating responsive email templates, built as a React embeddable component. It also serves as an AI-powered email designer, a collaborative email design tool, and a React component library for composing emails programmatically with JSX. The editor represents designs as structured JSON and supports multi-format rendering for email clients, web pages, and PDF. What distinguishes this editor is its deep AI integration: users can generate full email templates from natural language, rewrite text with chosen intent, produce multiple text vari

This project is a visual HTML email builder and responsive design tool used to create mobile-ready email layouts. It includes a dynamic email template engine and an artificial intelligence generator for drafting email copy and structural layouts. The system utilizes a component-based layout engine to build emails using standardized blocks and columns, which are translated into table-based HTML for compatibility across diverse email clients. It supports personalization through variable-based template interpolation and conditional logic to adjust content based on specific data sets. The platfo

React Email is a development framework for designing and testing HTML emails using a library of modular components. It provides a set of reusable UI primitives that allow developers to build email templates through declarative code, ensuring consistent visual presentation across various desktop and mobile email service providers. The framework functions by transforming component trees into static HTML markup, automatically handling the complex requirements of email client rendering. It includes a built-in engine that extracts style declarations and injects them directly into HTML elements, by

MJML is a responsive email framework and HTML email compiler that translates simplified semantic markup into complex HTML. It functions as an email template engine designed to produce layouts that render consistently across a wide range of email clients. The system provides a markup validation tool to check structural integrity and syntax before compilation. It also includes a version migration utility to upgrade older template files to newer language versions while preserving content and layout structure. The toolset covers several capability areas, including command-line markup compilation

Foundation Emails is a responsive HTML email framework designed to create layouts that render consistently across different screen sizes and email clients. It functions as a system for building responsive emails and includes a CSS inliner to convert external stylesheets into inline HTML attributes. The framework incorporates an HTML table layout generator that converts simplified custom tags into the complex table structures required for legacy email client rendering. This process automates the creation of layouts that maintain visual consistency in restrictive email software. The project pr

CssToInlineStyles is a CSS inliner for HTML emails that converts stylesheets into inline style attributes on HTML elements. It functions as a style resolver and transformation engine, mapping CSS selectors to HTML tags to ensure consistent visual rendering across diverse email clients and providers. The tool calculates final computed styles by applying specificity and inheritance rules before injecting the resolved properties directly into the style attributes of the corresponding HTML elements. It utilizes DOM-based style calculation and selector mapping to determine which declarations apply

This project is a Node.js email templating engine and SMTP delivery framework used for creating, rendering, and sending custom email templates. It provides a comprehensive suite for email orchestration, including a system for dispatching templated messages and a tool for generating custom layouts to standardize outbound messaging. The framework includes a dedicated HTML CSS inliner that converts external stylesheets into inline styles for consistent rendering across different email clients. It also features a multilingual localization tool for translating template text and subject lines, and

gluestack-ui is a cross-platform React component library built with Tailwind CSS. It provides over 30 pre-built, accessible components that can be installed by copying their source files directly into a project, giving developers full control over customization without external runtime dependencies. Every component implements WAI-ARIA patterns, keyboard navigation, and screen reader support out of the box. A key differentiator is the copy-paste architecture: rather than a traditional package dependency, component source code is placed in the project, allowing direct editing and eliminating ve

MUI is a lightweight CSS framework that implements Material Design visual and interaction guidelines for web interfaces. It provides a suite of tools for building interfaces through a responsive CSS grid system and a set of components based on standardized visual patterns. The library includes a customizable CSS theme engine and a specialized HTML email styling library. These tools allow for the modification of default palettes and visual styles to align an interface with a specific brand identity, while ensuring consistent rendering of email templates across different email clients. The fra

This project is a full-stack React starter kit and TypeScript web application boilerplate. It provides a pre-configured project template that combines a frontend and backend to accelerate the development of production-ready web applications. The kit is distinguished by its focus on type-safe architectures, utilizing a monorepo structure to synchronize data types between the server and client. It integrates specific implementations for SaaS operations, including recurring subscription billing via Stripe and user identity authentication supporting passkeys, social logins, and email verification

This project is a software engineering style guide and a curated collection of architectural patterns and coding standards. It provides a multi-language coding standard to ensure maintainable software across Ruby, Python, JavaScript, and Swift. The project establishes a development workflow specification for version control, continuous integration, and peer review to maintain a linear project history. It also includes a web accessibility framework based on ARIA and WCAG standards, using design tokens and semantic HTML patterns to build inclusive interfaces. The guides cover a broad range of

Mint is a front-end programming language and compiled web framework designed for building interactive user interfaces. It functions as a transpiler that converts a specialized domain-specific language into standard JavaScript and CSS for execution in a web browser. The toolchain enables type-safe UI development by utilizing static type analysis to validate data structures during the build phase. It organizes web interface logic into a component-based architecture, where encapsulated units synchronize internal state with the rendered view. The system covers a full compiled web toolchain, incl

Release is a cross-platform C++ framework designed for building high-performance native desktop applications. It provides a comprehensive suite of tools for constructing complex graphical user interfaces, utilizing a decoupled architecture that separates business logic from the visual layer through model-view-viewmodel patterns and observable data binding. The framework distinguishes itself by compiling declarative interface markup directly into native machine code, which eliminates runtime parsing overhead and optimizes execution. It further employs a cross-process rendering architecture tha

Slim is a concise, indentation-based template language and markup engine for generating HTML and XML. Designed for the Ruby ecosystem, it converts shorthand syntax into well-formed documents without the need for traditional closing tags. The engine functions as a multi-engine wrapper, allowing the integration of external rendering engines such as Markdown and Sass within a single template file. It also provides a command line interface for rendering templates and converting them between different markup formats. The system supports dynamic content generation through embedded Ruby logic, incl

Templ is a type-safe HTML templating engine and UI framework for Go. It provides a system for building reusable HTML components that compile into Go code for server-side rendering, ensuring type safety and compile-time validation of data and logic. The project features a dedicated language server that provides autocomplete and syntax validation for template files within supported code editors. It employs compile-time code generation to transform a custom template language into Go source code, enabling the creation of modular HTML fragments and logic blocks. The framework includes automated s

Blueprint-css is a CSS framework that provides a set of predefined styles and a responsive grid system for building consistent web page layouts and typography. It includes a browser style reset to remove default browser styling, ensuring a uniform visual starting point across different environments. The framework features a column-based responsive grid system that automatically adapts web content across various screen sizes and devices. It also includes a dedicated print stylesheet to optimize the appearance of web content specifically for physical printing. The project covers typography sta

Yew is a framework for building front-end web applications using Rust and WebAssembly. It provides a component-based architecture that allows developers to create modular, reusable user interface elements that manage their own state and logic. By compiling code into binary modules, the framework enables high-performance execution within modern browser environments. The framework distinguishes itself through a macro-based markup language that transforms declarative, HTML-like syntax into strongly-typed component structures during compilation. It features a robust server-side rendering engine t

Fomantic-UI is a component-based CSS library and frontend design system used to build consistent, responsive user interfaces. It functions as a CSS framework and responsive UI toolkit, providing a structured approach to managing typography, color palettes, and spacing. The project enables the development of custom UI components and the implementation of unified design systems across web applications. It provides a variable-driven theme compilation process to customize visual styles and a build-time system to compile selected components into production CSS bundles. The toolkit covers a broad

radzen-blazor is a UI component library for Blazor applications, providing a collection of native interface elements including data grids, charts, and scheduling components. It includes a data visualization suite for rendering complex datasets through interactive charts and heatmaps, alongside responsive web layout tools to ensure interfaces adapt to different screen sizes and orientations. The library offers multiple design system implementations, including a Fluent UI framework and a Material Design UI kit. Visual customization is supported through dynamic theme customization and brand conf

Vuestic UI is a Vue 3 component library providing a collection of pre-made user interface elements. It serves as a responsive UI framework and a themed component system designed to speed up frontend development and maintenance. The toolkit features a centralized configuration system for global styling and dynamic branding, including a built-in dark mode. It includes an internationalized interface toolkit with native support for localization and translating application content for multiple languages. The library provides a set of accessible web components that meet accessibility standards for

Mobi.css is a lightweight, mobile-first CSS framework designed to provide a consistent foundation for web interface development. It establishes a stable visual baseline by normalizing default browser styles across all platforms, ensuring that standard interface elements like buttons, forms, and text blocks maintain a cohesive appearance. The framework utilizes a flexible grid system based on container models that automatically adjust content dimensions and alignment to fit varying screen sizes and device orientations. By prioritizing mobile constraints and employing viewport-based breakpoints

Dopefolio is a customizable developer portfolio template designed for software engineers to showcase technical skills, project galleries, and detailed case studies. It is a responsive, multi-page static site featuring a central homepage and dedicated detail pages for individual technical project breakdowns. The template utilizes a CSS variable theming system that allows for instant site-wide updates to primary colors and visual styles. Its structure is optimized for search engines, employing a lean HTML hierarchy to ensure fast load times and high visibility. The project covers the presentat

Atomic Layout is a declarative framework for building responsive user interfaces in React. It functions as a layout engine that abstracts complex grid structures into reusable components, allowing for the creation of hierarchical spatial distributions without the need for manual media queries. The library distinguishes itself by mapping visual layout regions to component structures through dynamic grid-template-area generation. It utilizes a property-based system where components accept specific suffixes to automatically trigger responsive style adjustments based on viewport width. By employi

Mailtrain is a self-hosted newsletter platform and email marketing tool designed for managing subscriber lists and sending automated email campaigns from a private server. It provides a centralized system for coordinating the creation and delivery of recurring email outreach. The platform includes a visual email template builder for creating responsive layouts and a subscriber management system that uses custom fields to organize audiences into targeted segments. Automation is handled through tools that can trigger newsletters based on remote feeds and scheduled events. Performance is tracke