MailerSend vs Resend
Compare MailerSend and Resend based on observed API performance, features, and pricing
Live performance comparison
Real-world performance data from messages sent through Knock
| Provider | Message volume | Growth | Status page updates (30d) | Status page updates (90d) |
|---|---|---|---|---|
| <1M | 7th of 10 → | 1 | 1 |
| 10M–25M | 1st of 10 → | 9 | 20 |
From April 17th to July 16th, Knock routed <1M messages through MailerSend and 10M–25M through Resend. MailerSend reported 1 status page update over the last 90 days, while Resend reported 20.
Response time
Response time measures how long each provider takes to accept an API request from Knock, including connection overhead and any automatic retries. Lower values mean faster message hand-off.
| Provider | Median (p50) | p90 | p95 | p99 |
|---|---|---|---|---|
| 238ms | 492ms | 573ms | 881ms |
| 98ms | 166ms | 199ms | 435ms |
The chart above shows each provider's daily median response time (p50) from April 17th to July 16th. The top-line number is an average of these daily values: MailerSend averaged 238ms compared to 98ms for Resend. MailerSend's highest daily p50 was 586ms; Resend's was 122ms. Resend is 140ms faster at the median, which can add up at high volumes.
The 90th percentile (p90) captures the slowest 10% of requests, revealing how each provider handles moderate stress. Averaged across all days, MailerSend has a p90 of 492ms compared to 166ms for Resend. The highest daily p90 was 1993ms for MailerSend and 221ms for Resend. Resend handles these slower requests 326ms faster, suggesting more consistent performance across the board.
The 99th percentile (p99) represents the long tail — the slowest 1% of requests. Averaged across all days, MailerSend reached 881ms at p99 while Resend reached 435ms. The highest daily p99 was 8277ms for MailerSend and 10906ms for Resend This peak coincided with a major incident reported on Resend's status page (Degraded perfomance in Metrics)., indicating the worst-case response time during spikes or provider-side congestion. Resend shows a tighter tail, which may matter for time-sensitive notifications like one-time passwords or real-time alerts where even rare delays can impact user experience.
Error rate
Error rate tracks the ratio of 5xx responses and timeouts to total requests. Knock automatically retries failed requests, so transient provider errors rarely affect end-user delivery.
| Provider | Avg. daily error rate | Highest daily rate | Peak error date | Zero-error days | Days above 0.01% |
|---|---|---|---|---|---|
| 0.00% | 0.11% | Jun 30 | 88 | 3 |
| 0.01% | 0.57% | Jul 1 | 85 | 4 |
Averaged across the date range, MailerSend shows a 0.00% daily error rate compared to 0.01% for Resend. The highest single-day error rate was 0.11% for MailerSend and 0.57% for Resend. Both providers show similar reliability levels, with error rates well within acceptable thresholds. Knock automatically retries failed requests to both providers, minimizing the impact of transient errors on end-user delivery.
About these metrics: Data represents messages sent through Knock during the specified period. Response time measures time from Knock to provider acceptance. Error rate includes only provider 5xx responses and timeouts.
Recent MailerSend incidents
Recent status page incidents for MailerSend
Started Jul 1, 2026 — Resolved Jul 1, 2026
Status: Complete Maintenance has completed Affected components Bulk endpoint (Under maintenance) SMTP (Under maintenance) Delivery time (Under maintenance) Email sending API (Under maintenance)
Recent Resend incidents
Recent status page incidents for Resend
Started Jul 16, 2026 — Resolved Jul 16, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Website (Operational) Automations (Operational) SMTP (Operational) Broadcast Emails (Operational) Webhooks (Operational) Single Email (Operational) Dashboard (Operational) Email Events (Operational) Batch Emails (Operational) General API (Operational)
Started Jul 16, 2026 — Resolved Jul 16, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Webhooks (Operational)
Started Jul 12, 2026 — Resolved Jul 12, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Automations (Operational)
Started Jul 10, 2026 — Resolved Jul 10, 2026
Status: Resolved We have resolved the underlying issue and service has been resumed. Affected components Single Email (Operational) Dashboard (Operational) SMTP (Operational) Broadcast Emails (Operational) Batch Emails (Operational) General API (Operational)
Started Jul 3, 2026 — Resolved Jul 3, 2026
Status: Resolved We have resolved the underlying issue and services have been recovered. Affected components Single Email (Operational) SMTP (Operational) Broadcast Emails (Operational) Batch Emails (Operational)
Pros and cons
MailerSend
Resend
Pros
- Designed for both developers and business users with API and visual editor
- Modern, intuitive UI that is easier to navigate than older platforms
- Multi-channel support with native email and SMS transactional messaging
- Affordable Hobby plan at $7/month for 5,000 emails with low overage rates
Pros
- Beautiful documentation with attention to detail and great developer experience
- Created and maintain React Email, the go-to framework for building email templates in React
- Minimalist, developer-optimized platform that avoids bloat with a focused UI
- Transparent observability with real-time visibility into sends, failures, and engagement
Cons
- Available integrations with other tools are basic and limited
- Fewer advanced features than enterprise platforms
- Smaller ecosystem compared to established competitors
Cons
- Newer and less battle-tested compared to incumbents like Mailgun or SendGrid
- Fewer enterprise features than established providers
- Limited marketing email capabilities
Frequently asked questions
What is the difference between MailerSend and Resend?
Mailersend is an intuitive transactional email and SMS service by Mailgun, designed for growing businesses. Resend is a modern email API built for developers, with React Email support and a focus on simplicity. MailerSend is best suited for growing saas + e-commerce, while Resend is geared toward developer-first, react teams.
Which is cheaper, MailerSend or Resend?
Free tier includes 500 emails per month. Paid plans start at $7/month for 5,000 emails on the Hobby plan, with the Starter plan at $35/month for 50,000 emails. Free tier includes 3,000 emails per month and 100 emails per day. Paid plans start at $20/month for 50,000 emails with overages at $0.90/1K on Pro, scaling down to $0.46/1K on Scale 2.5M. The best value depends on your sending volume. Use the pricing calculator above to compare costs at your expected volume.
Which is faster, MailerSend or Resend?
Based on real-world data from Knock, MailerSend has a median API response time (p50) of 238ms compared to 98ms for Resend.
Which is more reliable, MailerSend or Resend?
From April 17th to July 16th, MailerSend showed an error rate of 0.00% while Resend showed 0.01%. Both rates are within acceptable thresholds for production email delivery, and Knock automatically retries failed requests to minimize the impact of transient errors.
Which is more popular, MailerSend or Resend?
On the Knock platform, MailerSend handled <1M messages from April 17th to July 16th compared to 10M–25M for Resend. MailerSend volume has remained stable, while Resend volume has remained stable.
Can I use both MailerSend and Resend together?
Yes. Knock enables you to integrate multiple email providers into a single notification workflow. You can use MailerSend and Resend side by side, route traffic between them, or migrate from one to the other without changing your application code.
What are the main pros and cons of MailerSend vs Resend?
MailerSend strengths include designed for both developers and business users with api and visual editor and modern, intuitive ui that is easier to navigate than older platforms. Resend strengths include beautiful documentation with attention to detail and great developer experience and created and maintain react email, the go-to framework for building email templates in react. On the other hand, MailerSend drawbacks include available integrations with other tools are basic and limited, while Resend drawbacks include newer and less battle-tested compared to incumbents like mailgun or sendgrid.
Use either provider with Knock
Knock enables you to integrate MailerSend, Resend, or any combination of email providers into a single notification workflow. Manage templates, orchestrate cross-channel delivery, and switch providers without changing your code.