Keplars

Keplars is a modern email infrastructure platform built specifically for solo founders, indie hackers, and startup teams who want to stop debugging emails and start building their products. It provides a complete solution for sending both transactional and marketing emails with full delivery visibility, sandbox testing, and seamless scalability. The platform is designed with a strong developer experience at its core, enabling teams to send their first email in under 5 clicks without needing to configure complex email infrastructure. What sets Keplars apart is its usage-based pricing model that charges based on email volume rather than contacts, making it uniquely affordable for early-stage products and MVPs. The platform supports OAuth email sending through Google Workspace or Outlook, meaning you can start sending professional emails without owning a custom domain. When you are ready to scale, Keplars provides full SPF, DKIM, and DMARC support for custom domains to maximize deliverability. With an average time to inbox of under 5 seconds and a 99.77% deliverability rate, Keplars ensures your critical communications reach your users reliably. The platform also offers 100% delivery transparency with detailed tracking for opens, clicks, and full email timelines all in one place. Native integrations with Vercel, React Email, Lovable, and Supabase make it easy to fit into any existing workflow, while the unified email editor combines code and drag-and-drop capabilities for flexible email creation. Keplars is trusted by industry leaders like Gitstart, Roostoo Labs, and FoundersBoxx for its reliability, simplicity, and predictable performance.

OAuth Email Sending

Start sending product emails immediately by simply connecting your Google Workspace or Outlook account. No custom domain is required, yet you retain full control over the sender name. This feature is ideal for MVPs and early-stage products where you want to validate your email workflows before investing in domain configuration. The OAuth integration handles authentication securely, so you can focus on building your product rather than managing email infrastructure.

Unified Email Editor

Keplars provides a single, powerful editor that combines both code editing and drag-and-drop functionality in one place. This means developers can write custom HTML templates while non-technical team members can visually design emails using the drag-and-drop interface. The unified approach eliminates the need to switch between different tools or maintain separate workflows for different team members, making email creation faster and more collaborative.

Sandbox Mode for Testing

Test your email workflows safely without consuming your actual usage quota. Sandbox mode allows you to send test emails to yourself or your team to verify templates, check rendering across different clients, and validate delivery logic before going live. This feature helps you catch issues early and iterate on your email designs without worrying about costs or accidentally sending test emails to real users.

Fully Dynamic Usage-Based Pricing

Keplars charges based on email volume, not the number of contacts in your database. This means you can scale your email sending independently from your contact list growth. You can add more domains, increase email volume, or enable additional features as your needs evolve without being locked into rigid plans based on contact counts. This pricing model is particularly valuable for startups with growing user bases but fluctuating email volumes.

Transactional Email for SaaS Products

Send critical transactional emails like password resets, welcome sequences, order confirmations, and two-factor authentication codes with high reliability. Keplars ensures these time-sensitive messages reach users within seconds, with full delivery tracking and visibility. The OAuth integration lets you start immediately, while the sandbox mode lets you test every flow before going live. As your user base grows, you can seamlessly add custom domains and scale your sending without rewriting any code.

Marketing Campaigns for Early-Stage Startups

Launch email marketing campaigns to engage users, announce features, or share product updates without needing a separate marketing platform. The unified email editor lets you design beautiful newsletters and promotional emails using either code or drag-and-drop tools. Schedule individual emails or send in bulk with full control over timing and targeting. The usage-based pricing means you only pay for what you send, making it cost-effective for startups experimenting with different campaign strategies.

Developer-Focused Email Workflows

Integrate Keplars directly into your development workflow using native integrations with Vercel, React Email, Supabase, and Lovable. The clear API and SDK suite supports Node.js, Python, Go, PHP, Ruby, and many other languages, making it easy to add email functionality to any application. Developers can iterate quickly by testing in sandbox mode, then promote to production with confidence. The platform handles deliverability configuration automatically, so you can focus on building features rather than managing email infrastructure.

Multi-Tenant Email Sending for Platforms

If you run a platform where your users need to send emails from their own accounts, Keplars makes this straightforward. FoundersBoxx, for example, uses Keplars to power both internal transactional emails and email sending for their users directly from their own accounts. The platform handles multiple domains and sender identities cleanly, with full SPF, DKIM, and DMARC support for each. This use case demonstrates how Keplars scales from a single team to a multi-tenant architecture without complexity.

How quickly can I start sending emails with Keplars?

You can send your first email in under 5 clicks. Simply connect your Google Workspace or Outlook account via OAuth, and you are ready to send immediately. No custom domain, no DNS configuration, and no lengthy setup process. The platform handles all the underlying infrastructure so you can start sending transactional and marketing emails within minutes of signing up.

Does Keplars support custom domains and deliverability configuration?

Yes, when you are ready to use a custom domain, Keplars provides full support for SPF, DKIM, and DMARC records. This ensures maximum deliverability and inbox placement for your emails. You can add your own domain at any time, and Keplars guides you through the configuration process. The platform also uses optimized infrastructure and multi-region routing to achieve an average time to inbox of under 5 seconds and a 99.77% deliverability rate.

How does Keplars pricing work and what is included in the free trial?

Keplars uses fully dynamic pricing based on email usage, not the number of contacts in your database. You scale emails, domains, and features independently, paying only for what you actually send. There is a 7-day free trial available with no credit card required. During the trial, you can send emails, test in sandbox mode, and explore all features to see if Keplars fits your workflow before committing.

Can I test emails without affecting my production usage or sending to real users?

Absolutely. Keplars includes a dedicated Sandbox Mode that lets you test email workflows safely without consuming your actual usage quota. You can send test emails to yourself or your team to verify templates, check rendering, and validate logic. This is perfect for iterating on designs, testing new features, or debugging issues before going live with real user communications.