MailOptin

MailOptin is a WordPress lead-generation and email-automation plugin that converts website visitors into subscribers with popups, slide-ins, notification bars and inline optin forms, then sends one-off newsletters and event-triggered automated emails. It connects WordPress to more than sixty email marketing platforms, CRMs, form plugins, e-commerce and membership systems — Mailchimp, ActiveCampaign, HubSpot, AWeber, Klaviyo, Brevo, Salesforce, WooCommerce and others — and can post optin submissions to an arbitrary endpoint through a generic webhook connection. MailOptin is self-hosted software rather than a hosted service: it publishes no product API, no OpenAPI and no client SDK, and all functionality runs inside the customer's own WordPress installation. Its own website, mailoptin.io, runs WordPress and does serve a public self-describing REST API together with an OAuth-protected Model Context Protocol server.

MailOptin is listed with 1 API on the APIs.io network. Tagged areas include Company, Email Marketing, Marketing Automation, Lead Generation, and WordPress.

The MailOptin catalog on APIs.io includes 1 event-driven AsyncAPI specification.

MailOptin’s developer surface includes documentation, getting-started guide, support, engineering blog, pricing, signup flow, changelog, and 19 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

50.7/100 developing ▬ flat Agent 39/100 agent ready Front door AI 1/6 silent Heartbeat 100/100 alive saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessPaid

1 API 1 MCP Servers

Company Email Marketing Marketing Automation Lead Generation WordPress Newsletters Webhook MCP Plugins

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 50.7/100 · developing

Contract Quality 8.3 / 21

Developer Ergonomics 6.9 / 17

Access Clarity 14.3 / 17

Operational Transparency 2.9 / 11

Contract Governance 1.9 / 10

Discoverability 6.4 / 9

Regulatory Posture 5.1 / 15

Agent readiness — 39/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document
Documented Reversibility +6 pts — a reversal operation in the contract, graded up when a window is documented too

5 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 39.0 — up to +15.3 composite points
Developer Ergonomics scores 40.5 — up to +11.9 composite points
Contract Governance scores 18.2 — up to +9.8 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/mailoptin/apis.yml: open an issue on github.com/api-evangelist/mailoptin to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Official SDKs on Packagist, pub.dev and Hex	builds-on	26.8 (thin)	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 2

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Model Context Protocol (MCP)

measured — observed by APIs.io (platform)

OAuth 2.0 Protected Resource Metadata

measured — observed by APIs.io (verified)

APIs 1

Individual APIs this provider publishes, each with its own machine-readable definition.

MailOptin Site REST API and MCP Server

The WordPress REST API served by mailoptin.io, plus the Model Context Protocol server exposed through the WordPress MCP Adapter at the mcp namespace. The REST root is a public, ...

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

MailOptin Site MCP Server

mailoptin.io runs a live Model Context Protocol server, exposed through the WordPress MCP Adapter as the `mcp` namespace of the site's REST API. It was discovered from the RFC 9...

MCP SERVER

MailOptin API pricing

Prices published by MailOptin, read 2026-10-28 from mailoptin.io/pricing/.

Plan	Price
Agency	$499 per year Includes: Unlimited Sites, Lead Generation, Email Automation, Newsletters
Pro	$289 per year Includes: For 3 Sites, Lead Generation, Email Automation, Newsletters
Standard	$99 per year Includes: For 1 Site, Lead Generation
Lifetime Pro Plan	Lifetime Pro Plan for $999 Includes: Pro plan, lifetime updates and premium features

Plan details, limits and sources →

Billed by: license · FinOps profile →

Pricing Plans 2

Published pricing tiers and plan structures.

Mailoptin Plans Pricing

4 plans

PLANS

Mailoptin Price Estimates

0 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Mailoptin Rate Limits

0 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Mailoptin Finops

FINOPS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Mailoptin Webhooks

ASYNCAPI

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Mailoptin Authentication

3 schemes

SECURITY

Mailoptin Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

Mailoptin Scopes

1 scope

1 scopes

SCOPES

Resources

Get Started 2

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

SignUp

SignUp

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

MCPServer

MCPServer

WellKnown

WellKnown

LLMsTxt

LLMsTxt

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Lifecycle

Webhooks

Conformance

Conventions

ErrorCatalog

Build 2

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

Access & Security 3

Authentication, authorization, and security posture

Authentication

Authentication

OAuthScopes

OAuthScopes

DomainSecurity

DomainSecurity

Operate 3

Status, limits, changes, and where to get help

Support

Support

ChangeLog

ChangeLog

RateLimits

RateLimits

Commercial 4

Pricing, plans, and the legal terms of use

Pricing

TermsOfService

PrivacyPolicy

Plans

Company 3

The organization behind the API

Website

Website

Blog

Blog

BlogRSS

BlogRSS

Source (apis.yml)

aid: mailoptin
name: MailOptin
description: 'MailOptin is a WordPress lead-generation and email-automation plugin that converts website visitors into subscribers
  with popups, slide-ins, notification bars and inline optin forms, then sends one-off newsletters and event-triggered automated
  emails. It connects WordPress to more than sixty email marketing platforms, CRMs, form plugins, e-commerce and membership
  systems — Mailchimp, ActiveCampaign, HubSpot, AWeber, Klaviyo, Brevo, Salesforce, WooCommerce and others — and can post
  optin submissions to an arbitrary endpoint through a generic webhook connection. MailOptin is self-hosted software rather
  than a hosted service: it publishes no product API, no OpenAPI and no client SDK, and all functionality runs inside the
  customer''s own WordPress installation. Its own website, mailoptin.io, runs WordPress and does serve a public self-describing
  REST API together with an OAuth-protected Model Context Protocol server.'
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: paid
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Paid
  confidence: high
  probe_state: covered
  source:
  - plans
  - authentication
  - scopes
  - rate-limits
  - security
  generated: '2026-11-06'
  method: derived
image: https://mailoptin.io/wp-content/uploads/2014/05/mailoptin-plugin-banner.png
url: https://raw.githubusercontent.com/api-evangelist/mailoptin/refs/heads/main/apis.yml
x-type: company
x-source: harvest:marketing-integration-graph
specificationVersion: '0.23'
created: '2026-08-12'
modified: '2026-08-12'
tags:
- Company
- Email Marketing
- Marketing Automation
- Lead Generation
- WordPress
- Newsletters
- Webhook
- MCP
- Plugins
tags_raw:
- Company
- Email Marketing
- Marketing Automation
- Lead Generation
- WordPress
- Newsletters
- Webhooks
- Model Context Protocol
- Plugins
apis:
- aid: mailoptin:mailoptin-site
  name: MailOptin Site REST API and MCP Server
  description: The WordPress REST API served by mailoptin.io, plus the Model Context Protocol server exposed through the WordPress
    MCP Adapter at the mcp namespace. The REST root is a public, self-describing route index — 35 namespaces and 771 routes,
    each with its argument schema — and content routes under wp/v2 answer anonymously. The MCP endpoint is live but auth-gated,
    returning 401 mcp_unauthorized with a WWW-Authenticate Bearer challenge that links to RFC 9728 protected-resource metadata.
    This is the company website's own surface, not a product API for the MailOptin lead-generation service, which ships as
    a self-hosted WordPress plugin.
  humanURL: https://mailoptin.io/
  baseURL: https://mailoptin.io/wp-json
  tags:
  - WordPress
  - MCP
  - OAuth
  - Authentication
  tags_raw:
  - WordPress
  - Model Context Protocol
  - OAuth
  - Authentication
  properties:
  - type: MCPServer
    url: mcp/mailoptin-mcp.yml
  - type: Authentication
    url: authentication/mailoptin-authentication.yml
  - type: OAuthScopes
    url: scopes/mailoptin-scopes.yml
  - type: ErrorCatalog
    url: errors/mailoptin-problem-types.yml
  - type: Conventions
    url: conventions/mailoptin-conventions.yml
  - type: RateLimits
    url: rate-limits/mailoptin-rate-limits.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://mailoptin.io/
- type: Documentation
  url: https://mailoptin.io/docs/
- type: GettingStarted
  url: https://mailoptin.io/section/getting-started/
- type: Support
  url: https://mailoptin.io/support/
- type: Blog
  url: https://mailoptin.io/blog/
- type: BlogRSS
  url: https://mailoptin.io/blog/feed/
- type: GitHubOrganization
  url: https://github.com/mailoptin
- type: Pricing
  url: https://mailoptin.io/pricing/
- type: SignUp
  url: https://my.mailoptin.io/login/
- type: TermsOfService
  url: https://mailoptin.io/terms-conditions/
- type: PrivacyPolicy
  url: https://mailoptin.io/privacy-policy/
- type: ChangeLog
  url: changelog/mailoptin-changelog.yml
- type: Lifecycle
  url: lifecycle/mailoptin-lifecycle.yml
- type: Plans
  url: plans/mailoptin-plans-pricing.yml
- type: RateLimits
  url: rate-limits/mailoptin-rate-limits.yml
- type: Packages
  url: packages/mailoptin-packages.yml
- type: Webhooks
  url: asyncapi/mailoptin-webhooks.yml
- type: Conformance
  url: conformance/mailoptin-conformance.yml
- type: Conventions
  url: conventions/mailoptin-conventions.yml
- type: ErrorCatalog
  url: errors/mailoptin-problem-types.yml
- type: Authentication
  url: authentication/mailoptin-authentication.yml
- type: OAuthScopes
  url: scopes/mailoptin-scopes.yml
- type: MCPServer
  url: mcp/mailoptin-mcp.yml
- type: WellKnown
  url: well-known/mailoptin-well-known.yml
- type: LLMsTxt
  url: llms/mailoptin-llms.txt
- type: DomainSecurity
  url: security/mailoptin-domain-security.yml
x-enrichment:
  date: '2026-08-12'
  status: enriched
  artifacts_added: 17
  pass: local-v1
x-coverage:
  state: covered
  reason: covered
  detail: MailOptin ships no product API, but mailoptin.io serves real machine-readable documents — RFC 8414 authorization-server
    metadata, RFC 9728 protected-resource metadata, a live OAuth-gated MCP server and a public 771-route WordPress REST index
    — all of which were fetched and recorded.
  evidence:
  - url: https://mailoptin.io/.well-known/oauth-protected-resource
    status: 200
  - url: https://mailoptin.io/wp-json/mcp/mcp-oauth-server
    status: 401
  checked: '2026-08-12'
x-vouched-by:
- Drip
- MailerLite
- SendPulse
x-vouch-count: 3

MailOptin API — frequently asked questions

Does MailOptin have an API?

Yes. APIs.io lists 1 API from MailOptin, including MailOptin Site REST API and MCP Server.

How do I authenticate with the MailOptin API?

MailOptin documents its authentication (3 schemes). The details are profiled on APIs.io as Mailoptin Authentication.

How much does the MailOptin API cost?

MailOptin publishes its prices; its Agency plan is $499 per year as of 2026-10-28. APIs.io lists 4 pricing plans for MailOptin, with each plan's price, limits and inclusions under Pricing on this page.

Does MailOptin have an MCP server?

Yes. APIs.io lists 1 MCP server for MailOptin: mailoptin.io runs a live Model Context Protocol server, exposed through the WordPress MCP Adapter as the `mcp` namespace of the site's REST API. It was discovered from the RFC 9728 protected-resource

Is the MailOptin API ready for AI agents?

MailOptin has a Kin Score of 50.7 out of 100 (developing) and an Agent Readiness score of 39.2 (agent-ready), scored by API Evangelist on 2026-11-06.

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