Sailthru

Sailthru is a cross-channel relationship-marketing and personalization platform built for media, publishing, retail and e-commerce brands, unifying email, SMS, mobile push, in-app and on-site messaging around a single customer profile with predictive segmentation and 1:1 content personalization. Founded in New York in 2008, it was acquired by CM Group (later Marigold) in 2018 and became part of Zeta Global in November 2025 when Zeta bought Marigold's enterprise software business; the product is now documented as Sailthru by Zeta. Its public HTTPS API lives at api.sailthru.com and covers users, lists, content, templates, blasts (campaigns), transactional sends, triggers, purchases, events, includes, ad plans and stats, authenticated with an api_key plus an MD5 signature computed over the request parameters. It is complemented by the Zephyr template language, a JavaScript on-site personalization tag, mobile SDKs, and API postbacks (webhooks) for opt-out, hardbounce, verify and profile-update events.

Sailthru is listed with 2 APIs on the APIs.io network. Tagged areas include Company, Email Marketing, Marketing Automation, Personalization, and Customer Data Platform.

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

Sailthru’s developer surface includes documentation, API reference, getting-started guide, support, engineering blog, signup flow, changelog, and 24 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

51.3/100 developing ▬ flat Agent 34/100 agent ready Front door AI 4/6 moderate Heartbeat 75/100 alive saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessApproval

2 APIs 1 MCP Servers

Company Email Marketing Marketing Automation Personalization Customer Data Platform Transactional Email SMS Push Notifications RetailMedia and Publishing

Kin Score

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

Composite quality — 51.3/100 · developing

Contract Quality 8.3 / 21

Developer Ergonomics 12.1 / 17

Access Clarity 7.4 / 17

Operational Transparency 7.6 / 11

Contract Governance 0.5 / 10

Discoverability 5.8 / 9

Regulatory Posture 5.4 / 15

Agent readiness — 34/100 · 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 0 / 6

Protected Resource Metadata 0 / 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 Telecommunications 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
Delegated User Identity +6 pts — a served discovery document listing authorization_code in grant_types_supported (served), else an oauth2 authorizationCode flow or openIdConnect declared in an OpenAPI (documented)

7 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
Contract Governance scores 4.5 — up to +11.5 composite points
Access Clarity scores 43.4 — up to +11.3 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/sailthru/apis.yml: open an issue on github.com/api-evangelist/sailthru 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
Commerce Platform Ecosystems (Shopify, WooCommerce, Stripe Apps)	builds-on	42.9	-	-
Reviews, Ratings and UGC (review platforms and who integrates with them)	builds-on	42.9	-	-
Mobile SDK Publishers (Play SDK Index, CocoaPods, ADA certification)	builds-on	42.9	-	-
Official SDKs on Packagist, pub.dev and Hex	builds-on	42.9	-	-

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 1

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 (verified)

APIs 2

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

Sailthru API

The core Sailthru HTTPS API. All requests are GET, POST or DELETE calls to https://api.sailthru.com/, authenticated with api_key, an MD5 sig over the sorted parameter values, an...

Sailthru JavaScript API (Personalization Engine)

The client-side Sailthru JavaScript tag (spm.v1.min.js, served from ak.sail-horizon.com) used for on-site behavior tracking, content-library sync, userSignUp/userSignUpConfirm c...

MCP Servers 1

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

Sailthru MCP Server

Remote MCP server at docs.zetaglobal.com over HTTP.

MCP SERVER

Sailthru API pricing

Rate limits

: 200 1s
: 300 1s
: 40 1s

All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

Sailthru Plans Pricing

0 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Sailthru Rate Limits

5 limits

RATE LIMITS

FinOps 1

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

Sailthru Finops

FINOPS

Event Specifications 1

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

Sailthru Postbacks Webhooks

ASYNCAPI

Security Posture 4

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

Sailthru Authentication

apiKey/requestSignature · 3 schemes

SECURITY

Sailthru Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Sailthru Vulnerability Disclosure

Bugcrowd · security.txt

SECURITY

Sailthru Trust Center

SOC 2 Type 2, ISO/IEC 27001, ISO/IEC 27018:2019, ISO/IEC 27701, HDS, Privacy Mark, SOX, GDPR, CCPA, HITRUST, SIG Core, CAIQ, SOC 1 Type 2

SECURITY

Resources

Get Started 3

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

SignUp

SignUp

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Components

Conventions

ErrorCatalog

Lifecycle

Conformance

Webhooks

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

Packages

SDKs

CLI

Access & Security 6

Authentication, authorization, and security posture

TrustCenter

TrustCenter

DomainSecurity

DomainSecurity

VulnerabilityDisclosure

VulnerabilityDisclosure

Security

Security

Compliance

Compliance

Authentication

Authentication

Operate 4

Status, limits, changes, and where to get help

Support

ChangeLog

ChangeLog

RateLimits

Commercial 3

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Plans

Plans

Company 2

The organization behind the API

Website

Website

Blog

Blog

Source (apis.yml)

aid: sailthru
name: Sailthru
description: Sailthru is a cross-channel relationship-marketing and personalization platform built for media, publishing,
  retail and e-commerce brands, unifying email, SMS, mobile push, in-app and on-site messaging around a single customer profile
  with predictive segmentation and 1:1 content personalization. Founded in New York in 2008, it was acquired by CM Group (later
  Marigold) in 2018 and became part of Zeta Global in November 2025 when Zeta bought Marigold's enterprise software business;
  the product is now documented as Sailthru by Zeta. Its public HTTPS API lives at api.sailthru.com and covers users, lists,
  content, templates, blasts (campaigns), transactional sends, triggers, purchases, events, includes, ad plans and stats,
  authenticated with an api_key plus an MD5 signature computed over the request parameters. It is complemented by the Zephyr
  template language, a JavaScript on-site personalization tag, mobile SDKs, and API postbacks (webhooks) for opt-out, hardbounce,
  verify and profile-update events.
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: unknown
  onboarding: approval
  trial: false
  try_now: false
  public: false
  label: Requires approval
  confidence: medium
  probe_state: covered
  source:
  - plans
  - authentication
  - rate-limits
  - security
  generated: '2026-11-06'
  method: derived
image: https://zetaglobal.com/wp-content/uploads/2025/12/ZetaMarigold-Landing-page-images-09-1.png
url: https://raw.githubusercontent.com/api-evangelist/sailthru/refs/heads/main/apis.yml
x-type: company
x-source: harvest:marketing-integration-graph
x-tier: profiled
x-tier-reason: enrichment
x-parent-company: 'Zeta Global Holdings Corp. (NYSE: ZETA)'
specificationVersion: '0.23'
created: '2026-08-12'
modified: '2026-08-12'
tags:
- Company
- Email Marketing
- Marketing Automation
- Personalization
- Customer Data Platform
- Transactional Email
- SMS
- Push Notifications
- Retail
- Media and Publishing
apis:
- aid: sailthru:sailthru-api
  name: Sailthru API
  description: The core Sailthru HTTPS API. All requests are GET, POST or DELETE calls to https://api.sailthru.com/<endpointName>,
    authenticated with api_key, an MD5 sig over the sorted parameter values, and a format parameter (json or xml). Endpoints
    cover user profiles, lists, content, templates, blasts (campaigns), transactional send, trigger, purchase, event, include,
    ad-plan, preview, settings, stats and bulk job operations.
  humanURL: https://products.zetaglobal.com/sailthru/Content/developers/api-basics/introduction.html
  baseURL: https://api.sailthru.com
  tags:
  - Email Marketing
  - Transactional Email
  - Marketing Automation
  - Personalization
  properties:
  - type: Documentation
    url: https://products.zetaglobal.com/sailthru/Content/developers/overview.html
  - type: APIReference
    url: https://products.zetaglobal.com/sailthru/Content/developers/api-basics/introduction.html
  - type: GettingStarted
    url: https://products.zetaglobal.com/sailthru/Content/developers/api-basics/technical.html
  - type: Authentication
    url: authentication/sailthru-authentication.yml
  - type: RateLimits
    url: rate-limits/sailthru-rate-limits.yml
  - type: ErrorCatalog
    url: errors/sailthru-error-codes.yml
  - type: Conventions
    url: conventions/sailthru-conventions.yml
  - type: Webhooks
    url: asyncapi/sailthru-postbacks-webhooks.yml
- aid: sailthru:sailthru-js-api
  name: Sailthru JavaScript API (Personalization Engine)
  description: The client-side Sailthru JavaScript tag (spm.v1.min.js, served from ak.sail-horizon.com) used for on-site behavior
    tracking, content-library sync, userSignUp/userSignUpConfirm calls and on-site personalization. It is the browser counterpart
    to the server-side API and is loaded as a script rather than called over REST.
  humanURL: https://products.zetaglobal.com/sailthru/Content/developers/api-client/javascript.html
  baseURL: https://ak.sail-horizon.com
  tags:
  - Personalization
  - JavaScript
  - Web
  properties:
  - type: Documentation
    url: https://products.zetaglobal.com/sailthru/Content/developers/api-client/javascript.html
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: TrustCenter
  url: security/sailthru-trust-center.yml
- type: DomainSecurity
  url: security/sailthru-domain-security.yml
- type: VulnerabilityDisclosure
  url: security/sailthru-vulnerability-disclosure.yml
- type: Security
  url: https://bugcrowd.com/engagements/cheetah-vdp
- type: Compliance
  url: https://trust.zetaglobal.com/?product=sailthru
- type: Website
  url: https://www.sailthru.com/
- type: DeveloperPortal
  url: https://products.zetaglobal.com/sailthru/Content/developers/overview.html
- type: Documentation
  url: https://products.zetaglobal.com/sailthru/Content/LandingPage.htm
- type: APIReference
  url: https://products.zetaglobal.com/sailthru/Content/developers/api-basics/introduction.html
- type: GettingStarted
  url: https://products.zetaglobal.com/sailthru/Content/developers/api-basics/technical.html
- type: Support
  url: https://zetaglobal.com/about/contact-us/
- type: Blog
  url: https://zetaglobal.com/resource-center/
- type: GitHubOrganization
  url: https://github.com/sailthru
- type: SignUp
  url: https://my.sailthru.com/
- type: TermsOfService
  url: https://zetaglobal.com/former-marigold-now-zeta-services-agreement/
- type: PrivacyPolicy
  url: https://zetaglobal.com/privacy-policy
- type: ChangeLog
  url: https://products.zetaglobal.com/sailthru/Content/ReleaseNotes/releasenotes-2026.htm
- type: ChangeLog
  url: changelog/sailthru-changelog.yml
- type: Packages
  url: packages/sailthru-packages.yml
- type: SDKs
  url: packages/sailthru-packages.yml
- type: CLI
  url: cli/sailthru-cli.yml
- type: Components
  url: components/sailthru-components.yml
- type: Authentication
  url: authentication/sailthru-authentication.yml
- type: Conventions
  url: conventions/sailthru-conventions.yml
- type: ErrorCatalog
  url: errors/sailthru-error-codes.yml
- type: RateLimits
  url: rate-limits/sailthru-rate-limits.yml
- type: Plans
  url: plans/sailthru-plans-pricing.yml
- type: Lifecycle
  url: lifecycle/sailthru-lifecycle.yml
- type: Conformance
  url: conformance/sailthru-conformance.yml
- type: Webhooks
  url: asyncapi/sailthru-postbacks-webhooks.yml
- type: LLMsTxt
  url: llms/sailthru-llms.txt
x-enrichment:
  date: '2026-08-12'
  status: enriched
  artifacts_added: 17
  pass: local-v1
x-coverage:
  state: covered
  reason: null
  detail: Documentation is public, server-rendered and fully readable at products.zetaglobal.com/sailthru; seventeen artifacts
    were harvested from it and from live probes. The one genuine gap is machine-readable contract — Sailthru publishes no
    OpenAPI, AsyncAPI, GraphQL, MCP or /.well-known/ surface anywhere.
  checked: '2026-08-12'
x-vouched-by:
- Lytics
- Persado
- Simon Data
- mParticle
x-vouch-count: 4

Sailthru API — frequently asked questions

Does Sailthru have an API?

Yes. APIs.io lists 2 APIs from Sailthru, including Sailthru API and Sailthru JavaScript API (Personalization Engine).

How do I authenticate with the Sailthru API?

Sailthru uses bearer-token authentication (apiKey/requestSignature · 3 schemes). The details are profiled on APIs.io as Sailthru Authentication.

Does Sailthru have an MCP server?

Yes. APIs.io lists 1 MCP server for Sailthru: Remote MCP server at docs.zetaglobal.com over HTTP.

Is the Sailthru API ready for AI agents?

Sailthru has a Kin Score of 51.3 out of 100 (developing) and an Agent Readiness score of 33.8 (agent-ready), scored by API Evangelist on 2026-11-06.

Work with this as data

Every provider here is available over the APIs.io API and to AI agents over MCP.

MCP server

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get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
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