Resend
Resend is a transactional/marketing email API founded by Zeno Rocha (ex-WorkOS/Liferay), Bu Kinoshita, and Jonni Lundy, YC Winter '23, backed by $18M Series A (a16z, Dec 2024) after a $3M seed. It maintains React Email, the open-source templating library (19,000+ GitHub stars, 2M+ weekly npm downloads). The official Node SDK (`resend` on npm) is at v6.x, pulling ~5.9M weekly downloads across 500+ dependent projects. Free tier: 3,000 emails/mo, capped at 100/day, 1 domain. Pro: $20/mo for 50K emails ($0.90/1K overage); Scale: $90/mo for 100K up to $1,150/mo for 2.5M, with per-1K overage sliding from $0.90 down to $0.46. Domain verification takes 1-2 business days. Current version/status: Node SDK v6.x (npm, July 2026). License: proprietary SaaS (SDKs MIT-licensed). Pricing: Free: 3,000 emails/mo (100/day cap, 1 domain); Pro: $20/mo for 50K emails or $35/mo for 100K ($0.90/1K overage); Scale: $90/mo (100K) up to $1,150/mo (2.5M), overage sliding to $0.46/1K; Enterprise custom. Maintained by Resend, Inc. (YC W23, VC-backed by a16z, Elad Gil, Vercel's Guillermo Rauch).
Pick Resend if you're a Next.js/React shop shipping transactional email fast — the API, SDK, and React Email templating are the smoothest DX in the category, and 3,000 free emails/mo covers most MVPs. Don't pick it for pure cost-at-scale sends: Amazon SES is roughly 9x cheaper per email past 100K/mo ($0.10/1K vs Resend's $0.46-0.90/1K) if you can stomach AWS console pain, and Postmark still beats it on raw deliverability reputation for transactional-only workloads. Resend's own users flag the honest weakness: pricing jumps unpredictably as usage crosses tier boundaries, and account suspensions after deliverability audits have hit legitimate senders with little warning. Known weakness: Users report unpredictable bill spikes past the advertised tiers and abrupt account suspensions after automated deliverability audits, sometimes with support taking 24+ hours to respond during an outage.
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