established · 3.0

Transactional Email

Score 26.6 / 100 40 providers 15 APIs Search apis.io →
Variants seen in the corpus: Transactional Emailtransactional-email

Providers using this tag (40)

Ranked by API Evangelist rating — Exemplar and Strong are expanded by default.

Exemplar 18 Complete, well-documented, and agent-ready
BrevoMarketingMarketing AutomationEmail Marketing29 APIs87.3Customer.ioBehavioral DataBroadcastsCampaignsCDP27 APIs87.3HubSpotAnalyticsCommerceContentCRM93 APIs82.4MailchimpCampaignsEmail MarketingMarketing AutomationNewsletters120 APIs81.5Amazon SESEmailEmail DeliverabilityEmail ServiceMarketing Email17 APIs79.7MailerLiteEmail MarketingAutomationNewslettersSubscribers9 APIs77.2SendGridEmailEmail APIMarketing EmailSMTP63 APIs77.0SendPulseMarketingMarketing AutomationEmail19 APIs75.7GetResponseEmail MarketingMarketing AutomationLanding PagesWebinars50 APIs74.1SMTP2GOEmailEmail DeliverySMTP11 APIs73.6LoopsEmailEmail APIMarketing Automation20 APIs72.3OrttoMarketing AutomationCDPCustomer Data PlatformAnalytics6 APIs71.9Campaign MonitorEmail MarketingCampaignsSubscribers1 API71.4PostmarkEmailsMessagingDeliverability47 APIs71.1PlunkEmailMarketingAutomation5 APIs70.6Zoho CampaignsEmail MarketingCampaignsMailing ListsSubscribers2 APIs69.8MoosendEmail MarketingMarketing AutomationCampaignsMailing Lists1 API67.9MailmodoEmailInteractive EmailAMP for EmailMarketing Automation8 APIs67.7
Strong 9 Solid coverage with minor gaps
SilverpopEmail MarketingMarketing AutomationCampaign ManagementDigital Marketing6 APIs64.9Benchmark EmailEmail MarketingCampaignsContactsAutomation30 APIs64.6MailerSendEmailSMTPMarketing8 APIs64.6DotdigitalMarketing AutomationEmail MarketingSMSMMS4 APIs63.4EmailOctopusEmailEmail MarketingNewslettersCampaigns6 APIs60.5KaleyraCPaaSMessagingSMSWhatsApp6 APIs57.4EnchargeEmail MarketingMarketing AutomationSoftware-as-a-Service16 APIs57.3Route MobileTelecommunicationsIndiaCPaaSMessaging6 APIs57.2SailthruCompanyEmail MarketingMarketing AutomationPersonalization2 APIs54.4
Developing 6 Usable, with meaningful gaps to close
listmonkEmailNewsletterMailing ListMarketing8 APIs52.5ResendEmailDeveloper ToolsMarketing Email13 APIs50.9AhaSendEmailDeveloper ToolsSMTP11 APIs49.2LoopsEmailMarketing EmailEmail Automation12 APIs46.8CoorpacademyCompanySoftware-as-a-ServiceCorporate LearningLMS14 APIs45.5SparkPostEmailMarketing EmailEmail Delivery12 APIs43.9
Thin 6 Limited public surface area
MailjetEmailEmail DeliveryMarketing EmailSMTP8 APIs38.9ZohoAnalyticsCollaborationCRMCustomer Service34 APIs38.5MailtrapEmailEmail DeliveryEmail SandboxEmail Testing3 APIs37.1MailerooEmailEmail DeliveryMarketing EmailSMTP2 APIs36.7MailPaceEmailMessagingSMTP4 APIs35.6MailgunEmailSMTPEmail Validation8 APIs34.0
Emerging 1 Early or largely undocumented
InboxEmailInboxMessagingDeliverability2 APIs13.4

APIs with this tag (15)

Ranked by the provider's API Evangelist rating — the Kin Score is scored per provider, not per API, so every API of a provider shares its band. How the rating works →

Exemplar 8 Complete, well-documented, and agent-ready
Customer.io App APIThe Customer.io App API is the workspace-management and outbound-messaging surface: trigger broadcasts, sen...87.3HubSpot Transactional Email APIThe transactional email API enables sending template-based transactional emails through HubSpot using the S...82.4SendPulse SMTP APITransactional email sending, delivery and bounce tracking, unsubscribe management and sender-domain identity.75.7GetResponse API v3The complete GetResponse API v3 — a JSON REST API of 220 operations across 141 paths and 42 product areas, ...74.1SMTP2GO Email APIREST API for sending transactional emails and SMS, managing sender domains, SMTP users, API keys, templates...73.6Campaign Monitor APIREST API for managing email campaigns, subscriber lists, transactional emails, segments, journeys, template...71.4Zoho Campaigns Email APIResource-oriented JSON REST API for sending email at volume from Zoho Campaigns. Covers transmissions (crea...69.8Moosend APIThe Moosend REST API (v3) enables programmatic access to email marketing and automation capabilities includ...67.9
Strong 4 Solid coverage with minor gaps
Kaleyra Email APISend single and batch transactional email (Email API v2) with domain management, templates, webhooks, and d...57.4Encharge Transactional Email APIREST API for sending transactional emails through Encharge. Accepts JSON at POST /v1/emails/send with exact...57.3SendClean Email APISendClean is Route Mobile's transactional and bulk email product, exposed as a JSON-over-HTTP-POST REST API...57.2Sailthru APIThe core Sailthru HTTPS API. All requests are GET, POST or DELETE calls to https://api.sailthru.com/, auth54.4
Developing 1 Usable, with meaningful gaps to close
Coorpacademy Email APITransactional email service backed by Mandrill, exposing one operation per templated message the platform s...45.5
Thin 1 Limited public surface area
Zoho ZeptoMailThe Zoho ZeptoMail API provides REST endpoints for sending transactional emails such as OTPs, password rese...38.5
Emerging 1 Early or largely undocumented
Mailgun Email APIMailgun provides a programmable email API for sending, receiving, tracking, and validating email at scale. ...13.4

Score breakdown

Frequency
46.5
log-scaled weighted occurrences
Breadth
1.1
spread across providers
Quality lift
73.7
mean composite of providers using it
Cohesion
0.0
strength of nearest seed neighbor

Related tags

SMTP 15 co-occurrences Marketing Email 8 co-occurrences Email Delivery 8 co-occurrences Deliverability 10 co-occurrences Email Marketing 16 co-occurrences Mailing Lists 6 co-occurrences Transactional 6 co-occurrences Email API 5 co-occurrences

Where this tag comes from

Provider tag35
Api tag15

Cohort brief

Auto-generated

The 40 providers in the APIs.io catalog tagged Transactional Email, scored on the Kin Score. Every figure below is computed from the catalog — nothing here is written.

Providers
40
all scored
Mean Kin Score
60.6
+39.9 vs catalog 20.7
Mean Agent Readiness
35
+25.3 vs catalog 9.7
Spread
13.4–87.3
median 64.6 · σ 16.9
How the 40 split by band
Exemplar 18Strong 9Developing 6Thin 6Emerging 1Minimal 0
Facet averages, against the whole catalog
FacetThis cohortCatalogDifferenceScored
Access Clarity 70.5 22.3 +48.2 40
Contract Quality 60.8 17.5 +43.3 40
Operational Transparency 53.2 11.3 +41.9 40
Developer Ergonomics 58.2 17.9 +40.3 40
Discoverability 79.9 60.4 +19.5 40
Contract Governance 23 6.4 +16.6 40

A facet is averaged over the members that carry it, not over the whole cohort — the “Scored” column is that count. Averaging an absent facet as zero would score our own coverage gaps as the providers’ posture.

What this cohort publishes
ArtifactThis cohortCatalogDifference
MCP server (any) 57% 16% +41
MCP server (first-party) 43% 7% +36
Agent Skills 0% 0% 0
OAuth scopes 30% 9% +21
Security 100% 88% +12
Arazzo workflows 8% 2% +6
Governance rules 38% 13% +25

mcp_pct counts any mcp/ artifact including ones API Evangelist derived from the provider OpenAPI; mcp_first_party_pct counts only servers the provider publishes. Prefer the latter.

Top by Kin Score
  1. 1 Brevo 87.3
  2. 2 Customer.io 87.3
  3. 3 HubSpot 82.4
  4. 4 Mailchimp 81.5
  5. 5 Amazon SES 79.7
  6. 6 MailerLite 77.2
  7. 7 SendGrid 77
  8. 8 SendPulse 75.7
  9. 9 GetResponse 74.1
  10. 10 SMTP2GO 73.6
Top by Agent Readiness
  1. 1 Loops 57.8
  2. 2 SendPulse 55.8
  3. 3 HubSpot 54.4
  4. 4 Customer.io 50.4
  5. 5 GetResponse 50.4
  6. 6 MailerSend 50.2
  7. 7 Brevo 49.6
  8. 8 MailerLite 49.1
  9. 9 Mailchimp 44.8
  10. 10 Dotdigital 41.8
All 40 members of this roster resolve to a scored provider in the catalog.Generated from the catalog build of 25 August 2026, across 26891 providers, using the same computation served by the APIs.io cohort API. Briefs are published for rosters of 5 or more scored providers; below that a distribution is not meaningful.

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