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An HTML5 creative is a ZIP of HTML, scripts and images. A seller’s ad server reads the ZIP when Apostra sends it, and it turns away a ZIP it cannot make clickable. That refusal arrives after you have saved the creative and moved on, so check these requirements before you upload.

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Declare exactly one click tag

An ad server finds the creative’s exit, the place a click goes, from a plain JavaScript declaration in an HTML file in the ZIP. Google Ad Manager works this way, and so do most ad servers. Declare one click tag in the main HTML file and use it for the exit:
The declaration has to match this form:
  • It starts with var, then the name clickTag, optionally followed by digits (clickTag, clickTag1, clickTag2). The name is case-sensitive.
  • It assigns a quoted string on one line, in double or single quotes. An empty string is fine, because the approved click-through replaces the value.
  • It is in an .html or .htm file. A declaration in a .js file is not found.
These forms are not detected. A ZIP that uses only them has no click tag, as far as the ad server is concerned: Declare one exit. A ZIP that declares two different click tags, for example clickTag and clickTag1, has two exits, and one approved click-through cannot fill both. Repeating the same clickTag declaration in more than one HTML file is one exit.

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The approved click-through replaces the declared value

The URL you wrote in var clickTag is not the final destination. When a Google Ad Manager seller receives the ZIP, its sales agent writes the click-through approved on the creative into the one click-tag declaration and leaves every other part of the ZIP unchanged. Use any valid https:// URL while you build the ZIP, and set the real destination on the creative. An ad server accepts a click-through only when it is a valid URI, so characters it would reject, such as spaces, braces and non-ASCII letters, are percent-encoded when the value is written. The URL decodes to the same destination.

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When Apostra warns you

When you bring an HTML5 ZIP to Apostra, whether you attach it in chat or upload it through the v2 buyer upload flow, Apostra opens the ZIP’s HTML files and checks for a click tag. V3 save_creative does not take a ZIP. If the check finds no click tag, or more than one different click tag, the ZIP is still saved and the reply carries a warning. The warning names the problem, says what to add, and links this page. It is a warning rather than a refusal because some sellers use another click mechanism. A seller whose ad server needs a detectable click tag, such as Google Ad Manager, still refuses the ZIP. Fix it by adding the declaration above to the main HTML file and saving the corrected ZIP to the creative. Apostra checks only a ZIP it receives in the upload itself. It does not download a ZIP you linked by URL.

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Declare the size

Every HTML5 creative needs a size, because a seller that lists one format per banner size matches the creative to a format by its size. Put it in the main HTML file:
Use the banner’s real pixel size. Apostra does not infer it from the file name, the CSS or the images. A creative with no size is refused when you save it, and nothing is saved. The ways to declare a size, including formatParams, are in Save an HTML creative with its size.

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Add a backup image when the seller asks for one

Some sellers’ HTML5 formats require a backup image, the still picture shown where HTML5 cannot run. Where a seller’s format requires one, the creative needs an image asset in the backup_image slot, and the format can also set a maximum file size for it. A creative with no backup image, or one over the limit, does not fit that format. Add the image to the creative and save it again.

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Third-party display tags (CM360 tags) for Google Ad Manager sellers

A tag from Campaign Manager 360 (CM360) can carry bracket placeholders such as [timestamp] or [gdpr]. Google Ad Manager (GAM) expands only its own %%…%% macros, so a CM360 placeholder reaches the page as written unless the seller’s sales agent handles it first. For a GAM-backed seller the sales agent handles an inline tag’s placeholders like this: Fill or remove a refused placeholder in the tag, then save the corrected tag. The refusal appears on the creative’s seller entry, as Creative sync outcomes describes. A GAM seller accepts a display tag in two forms, once the seller’s product declares the delivery type in supported_delivery_types:
  • inline_markup: the tag’s markup, sent unchanged as a third-party creative.
  • paired_redirect: the tag’s ad-request URL with its click-through URL. When the ad-request URL is a CM360 https://ad.doubleclick.net/ddm/ad/… URL, GAM runs it as an internal redirect, and CM360 handles clicks. Any other ad-request URL is sent as an image redirect with its click-through URL.
Saving a display tag is described in Bring data in.