MailSlinger

✨ Inspiration

We wanted a tool that let us send transactional or test emails using Mailgun instantly — no login, no dashboards, no clutter. Just API key in, email out. Most tools overcomplicate what should be simple.

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💌 What it does

MailSlinger lets users send emails via Mailgun directly from their browser using their own API key. It never stores or logs credentials. You can enter full email metadata, paste your HTML or plain text body, preview it live, and send — all in one lightweight, secure interface.

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🛠️ How we built it • Frontend: Tailwind CSS + shadcn/ui for a clean, fast UI • Toasts: sonner for real-time feedback • Backend: Minimal Node.js proxy to relay Mailgun API calls and bypass CORS • Security: API key is discarded immediately after use — no persistence, ever • Smart input parsing for chips, live previews, and seamless UX

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🧱 Challenges we ran into • Ensuring no sensitive data is ever persisted while still providing a polished UX • Implementing chip-style email fields that felt intuitive and didn’t break accessibility • Dynamically previewing HTML vs plain text emails with no external libraries

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🏆 Accomplishments that we’re proud of • Built a secure, clean email sender that respects user privacy • Created a great UX using only open-source UI primitives • No logins, no dependencies, no unnecessary backend bloat

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📚 What we learned • Handling HTML safely while rendering previews on the fly • Making UX feel effortless when parsing user-generated input • How to stay lean and focused on just the features that matter

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🚀 What’s next for MailSlinger • Add drag-and-drop support for full .html email files • Optional save/load profiles (locally) for power users • Dark mode & mobile optimization • Open-source the backend and publish a one-click deploy on Vercel