VAST Reader

VAST 2.0 / 3.0 / 4.0 / 4.2 · Wrappers · Macros · Pixels

Analyze, debug, and validate VAST tags. Nothing leaves your browser.

⚠ Certaines URLs peuvent être bloquées par CORS. Dans ce cas, copiez le contenu et collez-le dans l'onglet XML.
Glissez un fichier .xml ou .txt ici · ou parcourir
🔒 Vos tags VAST ne quittent jamais votre navigateur. Aucune donnée n'est envoyée sur nos serveurs. Aucun stockage sur votre appareil.

VAST Reader: debug a video ad tag online

The Flownect VAST Reader is a debugger for ad ops, SSPs, publishers, and video engineers. Paste VAST XML, enter a tag URL, or upload a file to inspect structure, wrapper chains, macros, tracking events, and an IAB-focused compliance summary. Analysis stays 100% local: nothing is sent to our servers.

Supports VAST 2.0 through 4.2 (including macro and pod-related changes). It helps surface common failure modes: unresolved macros, duplicates across wrapper levels, depth limits, or blocked pixels (HTTPS, CORS, browser policy).

Frequently asked questions (FAQ)

What is a VAST tag?
VAST (Video Ad Serving Template) is an IAB standard that describes in XML how to serve a video ad: media files, durations, tracking URLs, redirects to other tags (wrappers), and more.
What is a VAST Reader (debugger) for?
It helps you read and validate tag contents, follow wrapper resolution to the inline VAST, exercise tracking pixels, and spot macro inconsistencies — useful before launch or when filing a ticket with a partner.
How do I debug a VAST Wrapper?
A wrapper points to another VAST. The reader resolves the chain to the final document and highlights common issues (loops, excessive depth, inconsistent macros per IAB guidance).
Why are my tracking pixels not firing?
Frequent causes: macros still in %%…%%, HTTP URLs on an HTTPS site, CORS blocks in the browser, or duplicate macros across wrapper levels that break reliable measurement.
What is the difference between VAST 2.0 and VAST 4.2?
VAST 4.x extends the model (pods, viewability-oriented tracking, richer macros and errors). VAST 2.x/3.x rely more on the classic %%MACRO%% substitution pattern from ad servers.
What is a duplicate macro between wrapper levels?
The same macro (e.g. %%CACHEBUSTER%%) may be resolved differently at each hop, making impressions hard to dedupe. Best practice is to substitute it at a single coherent level.
Are my VAST tags sent or stored on your servers?
No. Processing happens in your browser; we do not keep your tags on our systems.