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Mailgun vs Resend

Resend scores higher on the AgentReady, 89/100 against 58/100. They differ on 13 of the 41 signals. Which ones decides whether an agent can adopt them without a person watching.

What each one is

Mailgun. Transactional Email Delivery Service & API for Developers.

Resend. Email platform for developers to deliver transactional and marketing emails at scale.

Where Resend is ahead

Resend passes public docs discoverable, llms.txt published and llms-full.txt / full agent docs, and Mailgun does not. That is discover, whether an agent can find the product at all without being told it exists.

It also holds understand: structured api reference, openapi / spec quality, request examples provided, response examples provided and limits / constraints documented. Mailgun misses those.

And on adopt, no mandatory sales call, programmatic credential creation and cli available. Mailgun misses those.

Finally, on operate, structured, predictable output and idempotency support. Mailgun misses those.

What neither does

Both fail errors and status codes documented, machine-readable errors, retry behavior documented, rate-limit behavior predictable. If your agent needs any of those, you will be building it yourself either way.

Score, pillar by pillar

The AgentReady splits into four pillars, scored separately, because a product can be easy to find and still impossible to adopt.

Discover. Resend leads 100 to 73. Mailgun misses public docs discoverable, llms.txt published, llms-full.txt / full agent docs; Resend misses nothing.

Understand is whether an agent can read the docs and work out how the API behaves before calling it. Resend leads 85 to 31. Mailgun misses structured api reference, openapi / spec quality, request examples provided, response examples provided, errors and status codes documented, limits / constraints documented; Resend misses errors and status codes documented.

Adopt. Resend leads 100 to 75. Mailgun misses no mandatory sales call, programmatic credential creation, cli available; Resend misses nothing.

Operate. Resend leads 71 to 53. Mailgun misses structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable; Resend misses machine-readable errors, retry behavior documented, rate-limit behavior predictable.

Pricing

Mailgun does not publish a machine-readable starting price and has a free tier. Resend starts at $0/mo and has a free tier.

Signal by signal

Which to pick

Resend clears more of the signals an agent needs, so it is the safer default for unattended use. Full profiles: Mailgun and Resend. Alternatives to each: Mailgun, Resend.

An agent can fetch this as data: POST /v1/compare {"slugs": ["mailgun", "resend"]}