Resend

Resend is an email API and platform for developers: transactional and marketing email, built around an API-first workflow and the open-source React Email component library. Billing is a free tier plus paid subscription tiers; see the pricing page for current plans.

Overview

• Founders: Zeno Rocha (CEO), Bu Kinoshita, Jonni Lundy
• HQ: San Francisco; fully remote team
• Started: open-source project in 2022, platform launch in 2023; Y Combinator (W23 batch)
• Website: https://resend.com/

Products

• Email sending API with SDKs for common languages, test mode and webhooks (delivered, opened, bounced, clicked)
• React Email (open source): build templates as React components. The 2024 Series A post cited about 300k weekly npm downloads and 14k GitHub stars; v6.0 is listed on the 2026 blog.
• Broadcasts (marketing email), contacts and audiences, analytics, deliverability tooling
• Newer features listed on the Resend blog: Inbound Emails, Templates, New Contacts Experience, Unsubscribe Topics, Automations, AI Email Editor, Email Skills (for coding agents), Resend CLI 2.0

Timeline

• 2023-07: $3M seed round (date and amount not re-verified in the sources listed)
• 2024-12-04: $18M Series A led by Andreessen Horowitz (a16z), with Y Combinator, Basecase and angels. At that point: 200,000+ developers signed up.
• 2025-04-23: acquired Mergent (serverless background jobs); Mergent sunset 2025-07-28.
• 2025-08-05: acquired Briefer (YC S23 data workspace); Briefer was open-sourced and sunset 2025-11-05.
• 2026: blog announces a 3,000,000-user milestone (date not stated in the listing); incident reports dated 2025-11-18 and 2026-02-15.

AI relevance

Resend’s blog features Replit and Raycast case studies; claims of broad adoption by AI-built apps are not independently sourced. “Email Skills” and the CLI target agent-driven workflows.

Open items

• Date and exact wording of the 3,000,000-user announcement not verified.
• Current tier names not checked.

Sources

• https://resend.com/about (fetched 2026-10-05)
• https://resend.com/blog and https://resend.com/blog/series-a (fetched 2026-10-05)
• Acquisition posts: https://resend.com/blog/resend-acquires-mergent, https://resend.com/blog/resend-acquires-briefer (via search results, 2026-10-05)