Preflight your HTML5 banner

Check a banner against an ad network's real requirements — size, dimensions, required tags, click integration, and forbidden external sources — before you upload it.

Provide the banner

ZIP, a single HTML file, or pasted code.

Choose ad network

We pre-select it from the banner when we can — limits and rules load automatically.

Awaiting input

Pick a network and add a banner to see the report.

Catch banner rejections before the ad server does

Ad networks bounce HTML5 creatives for small, avoidable reasons — an oversized ZIP, a missing or malformed clickTag, dimensions that don't match the declared ad.size, or an external font URL that a strict DSP like Amazon forbids. Banner Check runs every one of those checks right in your browser, so you catch problems in seconds instead of waiting on a rejection. Nothing is uploaded — your files never leave your machine.

It's built by Viewst, an AI ad-production platform that exports network-ready HTML5 banners at scale, and the ruleset mirrors Viewst's live ad-network export pipeline.

A dedicated validator for every ad network

Each network has its own page with that network's exact size limit, click integration, required vendor scripts and external-URL policy. Open one to validate against a single network or to read its full requirements: