New Feature: Our Unified Email Editor is now Live

Built for solo founders, indie hackers, and startups.

Email Infrastructure for Modern Product Teams

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.

7-day free trial. No credit card required.

< 5s Average Time to Inbox

Delivered fast via optimized infrastructure and multi-region routing.

99.77% Deliverability Rate

SPF, DKIM, DMARC-ready with trusted providers for maximum inbox placement.

100% Delivery Transparency

Track delivery, opens, clicks, and full email timelines in one place.

Trusted by world-class developers & industry-leading teams

Built to Work With Any Stack

One unified API that adapts to your language, framework, and workflow. Designed for developers in every ecosystem - from web apps to mobile to backend systems.

What is OAuth Email Domain?

Connect your Google Workspace, Gmail, or Microsoft Outlook account and start sending transactional emails in minutes. Customize the sender name to match your product, with no DNS, SPF, or DKIM configuration.

Schedule Your Emails

Send emails at the perfect moment with our powerful scheduling API. Whether it's a welcome series, appointment reminders, or time-sensitive notifications, schedule your transactional emails to arrive exactly when your users need them.

Marketing emails built for real engagement

  1. Basics
  2. Audience
  3. Template
  4. Schedule

Built for Deliverability, Not Headaches

The core capabilities that make Keplars a reliable transactional email engine.

Inbox Delivery Rate

99.77%

Faster Onboarding

10x quicker compared to traditional SMTP setups.

Fewer Failed Deliveries

70% fewer failures compared to traditional email systems.

Keplars is the confidence you need in a mail infrastructure provider

With Keplars Mail Service, you get instant setup for both transactional and marketing emails, enterprise-grade security, and proven inbox deliverability without the hassle of SMTP or app passwords.

See what makes Keplars different:

99.77% Uptime

Trusted by thousands of developers

What drives us

Keplars is removing friction from email infrastructure for transactional and product emails, giving developers a predictable, boring email-sending foundation, without ongoing setup or debugging - so teams can focus on the product, not email infrastructure.