Campaigns
Render Campaign HTML
Render a campaign to email-ready HTML for an embedded preview
POST
Render Campaign HTML
Render a campaign to the exact email-safe HTML that would be sent. Use this to show a visual preview inside your own dashboard or email builder without duplicating Sequenzy’s rendering logic.
The render applies everything the send path applies: your email theme and font, company branding and footer, localization, block visibility conditions, product recommendation blocks, and merge tags.
This endpoint is read-only. It requires the
campaigns:read scope and never
sends, schedules, or modifies anything. It uses POST only so personalization
input can travel in a request body.Request
string
required
Campaign ID.
string
Personalize as this stored subscriber. Use this or
subscriber, not both.
Because the rendered HTML then carries that subscriber’s details, this field
also requires the subscribers:read scope.object
Personalize as an ad-hoc contact that does not need to exist in your account.
Accepts
email (required), firstName, lastName, and customAttributes.
Use this or subscriberId, not both.object
Extra merge variables layered over the contact’s attributes.
string
Force a localization locale instead of deriving it from the contact.
string
Render a specific A/B test variant of this campaign.
boolean
default:"false"
Apply your company’s auto-UTM link decoration, as a real send would. Defaults
to
false so the preview shows your own clean URLs.Personalization
WithoutsubscriberId or subscriber, the campaign renders for a sample contact and merge tags resolve to empty values. The response’s personalized field tells you which happened.
Only a stored subscriber (subscriberId) can resolve subscriber-scoped content: block visibility conditions, product recommendations, and a working unsubscribe link. An inline subscriber covers name and attribute merge tags.
Passing subscriberId puts that subscriber’s data into the returned HTML, so it needs the subscribers:read scope on top of campaigns:read. Rendering for a sample contact or an inline subscriber needs only campaigns:read.
Checking merge tags
An email never shows a raw{{TAG}} to a recipient, so a tag that does not exist and a tag that is simply blank for this contact both render as an empty string. unresolvedMergeTags tells them apart:
"reason": "unknown"- nothing provides that name, so it will be empty for every recipient. Usually a typo, or a tag carried over from another platform."reason": "no_value"- the name is recognized but has no value for this contact.
unknown when the render had a source to check it against. Without the contact’s attributes nothing is checkable at all - a bare {{plan}} reads the same attribute map as {{subscriber.plan}} - so pass a stored subscriberId, or an inline subscriber that includes customAttributes. Beyond that, {{event.*}} needs sample event properties in variables, since a real send fills those from the enrolling event, and {{recommendedProducts.*}} needs a stored subscriberId the catalog has something to recommend for. Without those, the tags come back as no_value rather than being reported as typos. An optional attribute that this contact happens not to have set is kept out of unknown by checking the names other contacts in the account carry, which is subscriber data: that check needs the subscribers:read scope, so a key without it may report such a name as unknown.
An empty array means every tag in the email resolved.
What is not in the HTML
Per-send click-redirect wrapping, the open tracking pixel, and unsubscribe click tracking are applied at send time against a real email send record. A preview has no such record, so those are never present in the returned HTML - emitting placeholder versions would give you URLs that 404. Thetracking flag therefore controls auto-UTM decoration only, which is genuinely applied at render time.
Responses
Render Campaign HTML