Resend

Resend is a modern email API built by Resend, designed to replace legacy infrastructure providers like SendGrid and Mailgun for code-first teams. Founded in 2023 and YC-backed, Resend pairs a clean REST API with the open-source React Email component library, so engineers can ship transactional and marketing email using the same components they use to build their app.

What Resend does:

• •React Email templates design email layouts as React components for consistent, responsive output across Gmail, Outlook, and Apple Mail without hand-writing inlined HTML.
• •Clean REST API a single, well-documented endpoint sends transactional and broadcast email programmatically with first-class SDKs for Node, Python, Ruby, Go, and PHP.
• •Test mode simulate full email events without delivering messages, so you can preview templates and verify webhook payloads before flipping production access on.
• •Webhook event tracking delivery, open, click, bounce, and complaint events stream to your webhook in real time so you can build observability dashboards and analytics.
• •SMTP support legacy applications and CMS plugins keep working through standard SMTP credentials, so migration off SendGrid does not require a full code rewrite.
• •MCP support native Model Context Protocol integration lets AI agents trigger and manage email workflows alongside other tools.
• •Browser extension inspect email logs and template previews directly from the browser for faster debugging during development.
• •Broadcast and audience management a lightweight broadcast feature handles simple newsletter sends and audience segmentation without needing a separate marketing platform for early-stage teams.

Pricing:

• •Free $0/month: 3,000 emails per month with a 100 emails per day cap, ideal for prototypes and side projects.
• •Pro $20/month: 50,000 emails per month, custom domains, dedicated IP add-on, and priority support.
• •Scale $90/month: 100,000 emails per month with higher rate limits, advanced webhooks, and SSO for engineering teams.

Limitations:

• •Transactional and lightweight broadcast only Resend is built for code-triggered email and basic broadcasts. There is no full marketing-automation suite with drip sequences, A/B testing, or behavioural re-engagement flows. Plan to pair it with a dedicated lifecycle tool for those needs.
• •New accounts start in sandbox mode you cannot send to arbitrary recipients until you verify a domain and request production access. The approval is fast but creates a gating step before launch day.
• •Rate limit of 2 emails per second by default the default API throughput is 2 requests per second across all plans. Bulk transactional bursts (a flash-sale confirmation to thousands of users at once) will queue or hit the limit unless you contact support to raise it.
• •Free plan caps at 100 emails per day the 3,000-per-month allowance is rate-limited to 100 per day. A small e-commerce store with 200 daily orders will exhaust the free plan before noon and need to upgrade to Pro.
• •No drag-and-drop campaign builder non-technical marketers cannot author and ship campaigns visually. Email templates live in code (React Email), so engineering is in the loop for every change.