Email Infrastructure, Simplified Under Few Clicks. Keplars powers transactional and marketing emails with full delivery visibility, sandbox testing, and seamless scale - with strong developer experience, enabling you to send emails in under 5 clicks, and usage-based pricing. < 5s Average Time to Inbox, 99.77% Deliverability Rate, 100% Delivery Transparency. From Firebase triggers to Vercel edge functions, and from React Email to Handlebars - Keplars slots into your stack without changing how you build. Start instantly with an OAuth email managed domain, or switch to your own custom domain when you're ready. Managed domains work out of the box, while custom domains give you full control when you need it - without changing your integration.