The loading state is your most valuable inventory.

Every web page renders a skeleton placeholder before content arrives. Marrow turns that time into a brand surface — and improves your Core Web Vitals score at the same time.

See it live →How it works

MARRW

How it works

One script tag. Sub-50ms ad fetch. Zero layout shift.

Tag your skeleton

Add data-marrow-slot to any skeleton element on your page. Hero images, product cards, app shells — anywhere your users currently wait.

Marrow paints the load

The SDK detects the slot before first paint, fetches branded creative from our edge in under 50ms, and renders it inside the slot’s exact bounding box. Becomes the LCP element.

Real content takes over

When your content arrives, the creative fades back smoothly. Same bounding box, zero layout shift. The publisher’s CWV score improved. A brand got measurable attention. The user noticed nothing wrong.

The measured result

LCP cut by 63%. CLS held at zero.

Tested with a Playwright fleet against a representative news-article page under mobile / 4G conditions, 20 paired runs:

1339ms

Baseline LCP p50

487ms

Treatment LCP p50

−63.6%

LCP delta

0.000

CLS p75

Reproducible. See it live, or read the methodology in our integration brief.

Who it’s for

Publishers who want CWV wins. Brands who want attention.

If you’re a publisher

Marrow is a script-tag drop-in. Your Core Web Vitals scores go up — meaningful SEO benefit. You earn a revenue share on inventory that did not exist yesterday. No reflow risk. No change to your existing programmatic stack. We sell the inventory; you collect.

If you’re a brand

A new inventory class with measurable per-exposure attention quality. Premium CPMs justified by paint-timestamp and duration metrics rather than the IAB viewability standard that wasn’t designed for this. Brand-safe by construction; the creative inherits the publisher’s editorial context.

See the demo →