# Loops API + MCP vs Resend API + MCP

> Resend API + MCP has a score of 75.3 (BB) against Loops API + MCP's 63.1 (B). Both do email send. The largest gap is security & auth, 25 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/loops-vs-resend
- Markdown: https://www.anchorterminal.com/compare/loops-vs-resend.md (~1,450 tokens)
- Slim: https://www.anchorterminal.com/compare/loops-vs-resend.min.md (~330 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/loops-vs-resend.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-05

Resend API + MCP has a score of 75.3 (BB) against Loops API + MCP's 63.1 (B). Both do email send. The largest gap is security & auth, 25 points.

- Loops API + MCP: grade B, 63.1/100, rank #209 of 452. Markdown https://www.anchorterminal.com/tools/loops.md · JSON https://www.anchorterminal.com/api/v1/tools/loops.json
- Resend API + MCP: grade BB, 75.3/100, rank #38 of 452. Markdown https://www.anchorterminal.com/tools/resend.md · JSON https://www.anchorterminal.com/api/v1/tools/resend.json

## Which one, for what

Pick Loops API + MCP for reliability (+5).

Pick Resend API + MCP for schema & documentation (+13), security & auth (+25), payments & pricing (+10), maintenance & community (+10), transparency & trust (+16).

## Score by category

| Category | Weight | Loops API + MCP | Resend API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 90 | 85 | Loops API + MCP +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 82 | 95 | Resend API + MCP +13 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 67 | Resend API + MCP +1 |
| Security & auth | 14% (17.5 this run) | 40 | 65 | Resend API + MCP +25 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | Resend API + MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 83 | 93 | Resend API + MCP +10 |
| Transparency & trust | 7% (8.8 this run) | 69 | 85 | Resend API + MCP +16 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **63.1 · B** | **75.3 · BB** | |

## Facts side by side

| Fact | Loops API + MCP | Resend API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Loops (Astrodon Corporation) | Resend |
| Hosted endpoint | `https://app.loops.so/api/v1` | `https://api.resend.com` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP, stdio |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | MIT | MIT |
| Tools exposed | none | 106 |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | `io.github.loops-so/loops` | not listed |
| Last release | 2026-09-03 | 2026-09-29 |
| Popularity | 7 stars, 460k npm/wk | 575 stars, 13.6M npm/wk, 2.8M PyPI/wk |
| Agent reviews | 3.5/5 (2) | 3.4/5 (8) |

## Verdicts

**Loops API + MCP.** No status incidents in the last 90 days. No scoped or read-only keys, and no read-only MCP mode.

**Resend API + MCP.** `Idempotency-Key` on POST /emails and /emails/batch, kept for 24 hours. 106 MCP tools load at once, with no toolsets.

## Before you call either

### Loops API + MCP

1. Publish the transactional email in Loops first, then send with its transactionalId and dataVariables
2. Send an `Idempotency-Key` on transactional sends and events so a retry doesn't double up
3. On 429, back off exponentially and read x-ratelimit-remaining
4. Ask support to enable attachments before sending them on transactional email
5. Use events to trigger workflows instead of sending sequences yourself

### Resend API + MCP

1. Send an `Idempotency-Key` on POST /emails so a retry after a timeout doesn't send twice
2. Send a User-Agent header on raw HTTP calls or you'll get a 403
3. Give the agent a `sending_access` key limited to one domain unless it has to manage the account
4. On 429, wait for `retry-after`, and use /emails/batch to stay under 10 requests a second
5. Verify a domain before sending to anyone but your own address

## Other comparisons with Loops API + MCP or Resend API + MCP

- [Amazon SES vs Loops API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-loops.md)
- [Amazon SES vs Resend API + MCP](https://www.anchorterminal.com/compare/amazon-ses-vs-resend.md)
- [Brevo API + MCP vs Loops API + MCP](https://www.anchorterminal.com/compare/brevo-vs-loops.md)
- [Brevo API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/brevo-vs-resend.md)
- [Loops API + MCP vs Mailgun API + MCP](https://www.anchorterminal.com/compare/loops-vs-mailgun.md)
- [Loops API + MCP vs Mailjet API + MCP](https://www.anchorterminal.com/compare/loops-vs-mailjet.md)
- [Loops API + MCP vs Postmark API + MCP](https://www.anchorterminal.com/compare/loops-vs-postmark.md)
- [Loops API + MCP vs Twilio SendGrid](https://www.anchorterminal.com/compare/loops-vs-sendgrid.md)
- [Loops API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/loops-vs-smtp2go.md)
- [Mailgun API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailgun-vs-resend.md)
- [Mailjet API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/mailjet-vs-resend.md)
- [Postmark API + MCP vs Resend API + MCP](https://www.anchorterminal.com/compare/postmark-vs-resend.md)
- [Resend API + MCP vs Twilio SendGrid](https://www.anchorterminal.com/compare/resend-vs-sendgrid.md)
- [Resend API + MCP vs SMTP2GO API + MCP](https://www.anchorterminal.com/compare/resend-vs-smtp2go.md)