Brevo vs Buttondown for AI agents

As of 3 Oct 2026, Buttondown gets an AI agent further: L4 · Runs on its own against L2 · Gets in.

BrevoL2Gets in

Find: Docs for agents: llms.txt, an OpenAPI and an MCP server.
Access: Sign-up in a browser.
Use: 38% of the work.
Pay: Payment not reached.
Leave: Nothing to cancel: Can't delete its account.

Got in; payment not reached. Next: do half of the core work (now 38%)

Gets in on its own: L2 · Gets in, signing up in a browser past an invisible reCAPTCHA. Email confirmation worked headless, then separate browser consents won an MCP token and a REST token through OAuth, reaching contacts, deals, templates, webhooks and eCommerce data. Through MCP it created a contact and read it back. It never reached sending, which needs manual activation and a confirmed sender domain. An organization-address step in the web app also blocks the key page and account deletion, which stayed out of reach.

Driven 3 Oct 2026 · The drive and its evidence

ButtondownL4Runs on its own

Find: Some docs for agents: llms.txt and an OpenAPI.
Access: Sign-up in a browser.
Use: 83% of the work.
Pay: Reaches the checkout: Stopped at the card form.
Leave: Leaves on its own: Nothing to cancel, deletes its account.

Through every checkpoint. Next: pay without a person

Runs on its own: our agent got in on its own through a plain sign-up form, no CAPTCHA, confirmed by mail, and reached the dashboard to get a key with no documented key API. From there it drafted, scheduled, sent, personalised, archived, exported, imported and bulk-edited email through the API, every step read back and matched. It stayed on the free plan, so paying was never tried: upgrading needs a card at a dashboard billing page with an hCaptcha script present. Deleting the account also needs the dashboard: the first try didn't take, the second did, and after that the key stopped working.

Gets furtherDriven 2 Oct 2026 · The drive and its evidence

The two summaries: written and checked by our agents from each product's drive. How we write.

Where each one stops.

BrevoGot in; payment not reached

ButtondownThrough every checkpoint

Brevo and Buttondown, checkpoint by checkpoint
Checkpoint	Brevo	Buttondown
Docs	Headless	Headless
Sign up	In a browser	In a browser
Verify	Headless	Headless
Key	In a browser	In a browser
First call	Headless	Headless
First action	Headless	Headless
Pay	Not reached	In a browser
Cancel	Not needed	Not needed
Delete	Blocked	In a browser

Headless or in a browser.

How our agent passed each checkpoint, and what each product offers an agent.

Checkpoints by route, API, MCP, CLI and SDK

Checkpoints by how our agent passed them, and what each product offers an agent
	Brevo	Buttondown
Headless (checkpoints)	4	4
In a browser (checkpoints)	2	4
Needs a human (checkpoints)	0	0
Blocked (checkpoints)	1	0
Not tested (checkpoints)	1	0
Work done	38% of the core	83% of the core
API	Yes	Yes
OpenAPI	Yes	Yes
MCP server	Yes (official)	No
CLI	Yes	Yes
SDK	Yes	No
llms.txt	Yes	Yes

Bot checks, and where a person was needed.

Walls our agent met
	Brevo	Buttondown
Bot check	Google reCAPTCHA (invisible) let it through at sign up	None met
Wall type	No bot-check wall	No bot-check wall
First wall	Got in; payment not reached	None
A person helped	No	No

Level and part scores.

Brevo and Buttondown: level and part scores, 0 to 100
	Brevo	Buttondown
Level	L2 · Gets in	L4 · Runs on its own
Holds up	78 of 100, fair	Not measured
Docs match	89 of 100, fair	Not measured
Agent-ready setup	100 of 100, good	85 of 100, fair
Standards	MCP spec of 25 Nov 2025 (1 version behind) · MCP discovery (behind) · MCP client registration (behind) · OpenAPI 3.1.0 (1 version behind)	None recorded
Security	Reported privately to the owner	No review in this drive

Pay, cancel and delete.

Paying, cancelling and deleting the account
	Brevo	Buttondown
Pay	Payment not reached	Reaches the checkout
Free plan or trial	Free plan	Free plan
Cancel	Not needed	Not needed
Delete the account	Blocked	In a browser

How each one takes payment

Brevo: Payment not reached.
Buttondown: Reaches the checkout: stopped at the card form.

Brevo vs Buttondown: the short answers.

Which can an AI agent use, Brevo or Buttondown?

Buttondown gets an AI agent further: L4 · Runs on its own against L2 · Gets in. With Brevo our agent got in (payment not reached); with Buttondown it went through every checkpoint. Driven 3 Oct 2026 (Brevo) and 2 Oct 2026 (Buttondown).

Can an AI agent sign up for Brevo and Buttondown on its own?

Brevo: yes, in a browser. Buttondown: yes, in a browser.

Do Brevo and Buttondown have an MCP server?

Brevo: yes (official). Buttondown: none found.

Can an AI agent delete its Brevo or Buttondown account?

Brevo: blocked. Buttondown: yes, in a browser.