VAST Tester AleksUIX

A modern, vastlint-powered VAST validator, debugger, and QA workbench.

If you are looking for a new and improved alternative to the IAB Tech Lab VAST Tester, this repository is meant to be that starting point. It keeps the familiar idea of a browser-based VAST tester, but adds deeper validation, wrapper inspection, playback diagnostics, tracking visibility, and shareable findings for real ad-tech workflows.

This project is built on top of vastlint, the Rust-based VAST validation engine behind vastlint.org. It is an independent open-source project and is not affiliated with or endorsed by IAB Tech Lab.

Looking for the IAB Tech Lab VAST Tester?

If that search term brought you here, the short version is this: this repo is an open-source, modernized VAST tester built for teams who want more than a legacy pass/fail checker.

It is designed for buyers, sellers, SSPs, DSPs, SSAI teams, QA engineers, and ad-ops workflows that need to:

• validate VAST XML against the IAB VAST specification
• inspect wrapper chains and resolved ads in detail
• understand tracking, macro expansion, and playback behavior
• share findings quickly with partners, vendors, or internal engineering teams

What This Repo Does

• Validate pasted VAST XML or a remote VAST URL
• Auto-fix deterministic issues that vastlint can repair
• Resolve wrapper chains through vastlint-client
• Inspect wrapper hops, resolved ads, media files, and rule findings in one UI
• Display findings inline while editing XML
• Review playback-oriented runtime signals, tracking waterfalls, and macro previews
• Switch between different compliance-oriented validation profiles
• Export reports and copy error summaries for partner debugging

Built on vastlint

This UI is the interactive frontend layer for the broader vastlint ecosystem.

• Core project: github.com/aleksUIX/vastlint
• Hosted web validator: vastlint.org
• npm package: npmjs.com/package/vastlint

Use this repo when you want a browser-first debugging workflow. Use vastlint directly when you want CLI automation, CI checks, MCP integration, or to embed VAST validation inside another system.

Getting Started

This app currently depends on local file-based packages from a sibling vastlint checkout in ../vastlint.

Recommended workspace layout:

your-workspace/
	vastlint/
	VAST-Tester/

Install dependencies:

npm install

Start the dev server:

npm run dev

Create a production build:

npm run build

Deploy

This repo is intended to stay separate from vastlint-infra and deploy directly to Cloudflare Pages on the custom hostname iab-tech-lab-vast-tester.vastlint.org.

One-time Cloudflare auth on your machine:

npm run cf:login

One-time Pages project creation:

npm run cf:pages:create

Deploy the current branch from your local machine:

npm run deploy:pages

After the first successful deploy, attach the custom domain in Cloudflare Pages:

iab-tech-lab-vast-tester.vastlint.org

This workflow avoids GitHub Actions and repo secrets while keeping deployment repeatable from the local CLI.

Why This Exists

The goal is not to reproduce the old tester one-to-one. The goal is to provide a stronger open-source workflow for anyone searching for an IAB Tech Lab VAST Tester style tool, but needing more visibility into why a tag fails, how wrappers resolve, what media is actually returned, and where tracking or compliance issues appear.

Notes

• The app depends on local file-based packages in ../vastlint.
• For URL-backed validation, the target endpoint must allow browser-side fetching from your local dev or deployed origin.
• Browser playback results can vary based on codec support and remote asset permissions.