Open Source TypeScript Email Software

Proton Web Clients is a monorepo hosting the web applications for Proton’s suite of privacy-focused services, including the core Proton Mail webmail interface and related web apps like Proton Calendar, Proton Drive, Proton Account, Proton VPN, Proton Pass, and other connected tools. It consolidates all web client code, shared modules, dependencies, and development tooling into a single repository, enabling unified maintenance, consistency of design patterns, and efficient evolution of Proton’s online interfaces. These web clients run entirely in the browser, letting users securely interact with their email, calendars, files, and other services without needing native software installed, and benefiting from end-to-end encryption where applicable. The monorepo includes application logic, UI components, build scripts, and testing infrastructure for reliable deployments and streamlined continuous integration.

react-email is a modern library for building responsive email templates using React components, bringing familiar frontend development practices into email design. It allows developers to create emails using reusable components, making it easier to maintain consistency across different templates and campaigns. The library supports rendering to HTML that is compatible with major email clients, addressing common challenges such as inconsistent styling and layout issues. It integrates seamlessly with modern JavaScript tooling, enabling developers to use TypeScript, JSX, and component-based design patterns. React Email also provides utilities for previewing emails locally, improving the development workflow by allowing quick testing and iteration. Its focus on developer experience makes it particularly appealing for teams that already use React in their applications. Overall, React Email modernizes email development by applying component-driven design to a traditionally fragmented space.

Agentic Inbox is a self-hosted email client that integrates an AI agent directly into the inbox experience, enabling automated reading, organization, and drafting of emails. It runs entirely on Cloudflare Workers, using serverless infrastructure to manage incoming and outgoing messages without relying on external email services. Each mailbox is isolated with its own storage, ensuring data separation and security while maintaining performance. The system supports full email functionality, including sending, receiving, threading, and attachment management through a modern web interface. Its AI agent can search conversations, summarize messages, and generate replies, while still requiring human approval before sending. The architecture combines durable state management, storage services, and AI inference into a unified workflow. Overall, it serves as a reference implementation for building AI-powered communication tools with full control over data and infrastructure.

Arcjet helps developers protect their apps in just a few lines of code. Implement rate limiting, bot protection, email verification, and defense against common attacks. Native security for Bun, Next.js, Node.js, SvelteKit, Vercel, Netlify, Fly.io, and other modern platforms. Customizable protection for signup forms, login pages, API routes, and your whole app. Test security rules locally. Protection that works in every environment. No agent is required.

ElectronMail is an Electron-based unofficial desktop client for ProtonMail. The app aims to provide enhanced desktop user experience enabling features that are not supported by the official in-browser web clients. It is written in TypeScript and uses Angular. The way of verifying that the installation packages attached to the releases have been assembled from the source code is being provided. The app works on Linux/OSX/Windows platforms. Binary installation packages. Offline access to the email messages (attachments content not stored locally, but emails body content). The local store feature enables storing your messages in the encrypted database.bin file (see FAQ for file purpose details). So the app allows you to view your messages offline, running full-text search against them, exporting them to EML/JSON files. etc. Enabled since v2.0.0 release.

An open source auto dialer and broadcasting platform built on FreeSWITCH and the ICTCore framework. It runs outbound campaigns across voice, fax and SMS from one interface. Campaigns are multi-tenant, so a service provider can give customers their own logins, contacts and reporting without running separate installations. IVR flows are built with a drag and drop designer rather than written by hand, which matters when the person designing a survey or a press-one campaign is not the person who administers the switch. GPL-3.0 licensed, with Docker images published for the application and for the ICTCore engine underneath it. Note that this open source edition runs on FreeSWITCH. The hosted commercial service of the same name is a separate product built on Asterisk.

Nexus is a desktop hub for Windows that keeps the web apps you use all day in one window, pinned to a sidebar and one keyboard shortcut away. What sets it apart is session isolation. A browser only holds one WhatsApp Web session at a time: opening a second account signs the first one out. Teams is no better, and Microsoft's own answer is to use another browser. Nexus gives every service its own isolated session, so two WhatsApp numbers and two Teams organisations stay signed in at once. It also does the ordinary things well: native Windows notifications with per-service mute, unread badges in the sidebar, taskbar and tray, a catalogue of common services plus any custom URL, drag-and-drop ordering, and per-service sleep to give memory back. Nexus tracks the stable Electron line, which decides whether those services keep working: they drop support for old browser engines twice a year. Free, open source under the MIT licence. English, French and Spanish.