vastlint

VAST Tag Tester

Test a VAST tag URL with a free online VAST tester

Paste a live VAST URL or raw XML into the editor below to fetch the tag, preview the creative, inspect tracking and click URLs, and catch delivery issues before launch.

Drop a .xml file or URL · paste XML or a URL · auto-validates · ⌘↵ to validate now

Quick start

Start with the editor, then review the results below it

  1. 1
    Paste a live VAST URL or raw XML. The tester auto-detects URLs, fetches XML when needed, and also supports drag-and-drop .xml files.
  2. 2
    Let the test run automatically. Validation starts after paste or while you type, so the editor stays the main workspace instead of making you jump through extra controls.
  3. 3
    Use the panels below the editor to QA the tag. Review rule violations, creative preview, companion assets, tracking vendors, and click URLs before launch.

At a glance

Full

rule coverage

6

VAST versions

<1ms

validation

0

data stored

Best for: live URL QA, creative preview, tracking inspection, click URL checks, and pre-launch delivery review.

Use the inspector instead: when you only need hop-by-hop wrapper debugging without the preview workflow.

What you get after a test

Creative preview

Preview the video ad, companion banners, and media assets in one place.

Tracking vendors

See which vendors fire tracking pixels and inspect their endpoints quickly.

Click URLs

Review click-through and click-tracking URLs without digging through raw XML.

Spec validation

Every issue is mapped to a rule, severity, and relevant spec guidance.

Pick the right tool

VAST Tag Tester

Best when you want end-to-end QA with preview, tracking, and click URL checks.

VAST Tag Validator

Best when you already have raw XML and only want pure spec compliance.

VAST Inspector

Best when the real problem is wrapper depth, redirects, or response-by-response tracing.

VAST tag tester FAQ

These answers are tailored to the main queries that should land on the tester: testing a live VAST URL, previewing ad creative, checking click tracking, and comparing the tester with the validator.

What is a VAST tag tester?

A VAST tag tester lets you test a live VAST URL or pasted XML end to end. It fetches the tag, previews the creative, shows tracking and click URLs, and helps catch delivery issues before launch.

How do I test a live VAST URL?

Paste the live VAST URL into the tester. The tool fetches the XML, validates it, previews the creative when possible, and shows tracking vendors, click URLs, and delivery signals in one workflow.

Can I preview a VAST creative before launch?

Yes. The tester is designed for pre-launch QA. It helps you preview the ad creative, inspect companion assets, review click-through behavior, and spot inconsistencies before traffic is sent to the tag.

What is the difference between a VAST tester and a VAST validator?

A VAST tester is for end-to-end QA on a live tag or XML. It adds URL fetching, creative preview, tracking inspection, and click URL review. A VAST validator is narrower and focuses on XML correctness and spec compliance.

Can I inspect click tracking and vendor pixels in a VAST tag?

Yes. The tester surfaces click URLs, click tracking, and vendor-related tracking signals so you can review where user actions and measurement calls are going without manually parsing the XML.

What is the best tool for testing a VAST tag before launch?

Use a VAST tag tester when you need more than pure validation. It is the right tool for final QA on a live tag because it combines URL fetching, preview, tracking inspection, click URL checks, and rule-based validation in one place.

Can I test raw VAST XML online?

Yes. You can paste raw VAST XML directly into the tester or upload a .xml file. The tool validates the XML, inspects the tracking and click URLs it contains, and helps you review the ad before launch.

Can I test VAST click-through URLs before launch?

Yes. A VAST tester is useful when you want to check the click-through destination and review click-tracking URLs before traffic starts hitting the ad tag in production.

How do I preview a VAST ad without sending live traffic?

Use the tester in a pre-launch QA workflow. Paste the live tag URL or XML, let the tool fetch the response, and review the creative preview, companion assets, and tracking behavior before the campaign is live.

Can I use a VAST tester for DV360, GAM, FreeWheel, or SSP tags?

Yes. If the platform gives you a live VAST tag URL or XML response, the tester can help you QA it. That makes it useful for tags coming from ad servers, SSPs, DSPs, or wrapper partners.

What should I check in a VAST tag before launch?

Before launch, check whether the live tag resolves, whether the creative previews correctly, whether click URLs and tracking vendors look correct, and whether the XML passes rule-based validation without serious errors.

Why does a VAST tag pass validation but still fail in the player?

A tag can pass pure XML and spec validation but still fail in playback because of wrapper behavior, tracking issues, missing assets, bad click URLs, or player-specific delivery problems. That is why a tester is useful in addition to a validator.

Need XML-only checks instead? Use the VAST Tag Validator instead. Need hop-by-hop redirect debugging? Open the VAST Inspector.

Need deeper docs after testing? Read the VAST tag testing guide →