Resend

Resend is an email sending platform built for developers, offering a REST API, SMTP relay and official SDKs for Node.js, PHP, Python, Ruby, Go, Rust, Java, Elixir and .NET, plus a CLI and serverless-oriented integrations. Core functionality covers transactional and marketing (broadcast) sending, scheduled and batch sending, inbound email, open and link tracking, modular webhooks for delivery, open, click, bounce and complaint events, a test mode for simulating events without sending to real recipients, contact management and broadcast analytics.

A second pillar of the product is email authoring. Resend maintains React Email (react.email), an open source component library that lets developers build templates in React rather than HTML table layouts, and also provides a visual editor for non-engineers to write and style broadcasts. Deliverability tooling includes DKIM/SPF/DMARC verification, DNS and IP monitoring, proactive DNSBL/Spamhaus blocklist tracking with removal requests, automatic suppression lists aligned with standards such as CAN-SPAM, BIMI/VMC guidance, shared IP pools and fully managed dedicated IPs that warm up and autoscale.

The platform is multi-region, allowing sends from North American, South American, European and Asian regions to reduce time-to-inbox. Enterprise-oriented controls listed on the pricing page include SOC 2 Type II certification, GDPR compliance, penetration testing, DDoS protection, automated backups, MFA, API key permissions and signed webhook endpoints. More recent additions include an in-app AI assistant with monthly AI credits by plan, natural-language email scheduling and deliverability insights.

Founding story

Zeno Rocha, previously CPO at Liferay Cloud and VP of Developer Experience at WorkOS, repeatedly encountered deliverability problems and poor tooling when sending email at scale, which motivated him to build a developer-first email platform. He co-founded Resend with Bu Kinoshita, the first engineering hire at WorkOS, who serves as co-founder and CTO and builds react.email. Rocha is originally from Brazil and is based in San Francisco.

Business model

Self-serve SaaS with a usage- and feature-tiered subscription model, sold primarily to engineering teams and supplemented by paid add-ons and enterprise contracts.

Tiered plans — Free (100 emails/day, 1 custom domain, 30-day retention, 1 webhook endpoint, 5 AI credits/mo), Pro and Scale (no daily limit; 10 and 1,000 custom domains respectively; 100 and 500 AI credits/mo), and Enterprise (flexible limits and contract-set domain limits, Slack support and urgent-response SLA). Add-ons include $20/month for 100 additional domains on Pro and Scale, and $30/month for a managed dedicated IP available to Scale customers exceeding 3,000 emails per day. The pricing page also references AI-agent-specific pricing and asks about annual, non-profit and education discounts.

Traction

By July 2023, roughly six months after the January 2023 public launch, Resend reported over 10,000 signed-up developers and more than 7 million transactional emails sent, with React Email above 8,000 GitHub stars and 80+ contributors. By the December 2024 Series A, 18 months after public launch, the company reported more than 200,000 developers signed up, millions of transactional and marketing emails per day, and React Email at 300,000 weekly npm downloads, 14,000 GitHub stars and 130+ contributors. Y Combinator lists a team size of 45.

Latest developments

The December 2024 Series A announcement cited newly shipped natural-language email scheduling and deliverability insights, and planned support for receiving email, contact segmentation and personalization. Current site and pricing pages show inbound email, an AI assistant with plan-based AI credits, AI-agent pricing, SOC 2 Type II certification, and a company event called Resend Forward.