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 publishes 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.
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
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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/.
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 github.com/api-evangelist/sailthru: open an issue to ask a question, or submit a pull request to add artifacts.
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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 parame...
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...
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