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Vastlint, inline linting for ad tags in VS Code, Kiro, Cursor

by aleksuix·Apr 20, 2026·4 points·0 comments
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AI Analysis

●●●BangerNiche GemSolve My Problem

Inline VAST linting in VS Code beats web validators for catching ad tag errors early.

Strengths
  • •108 rules covering full IAB spec versions prevents costly revenue-leaking errors.
  • •WASM core enables local validation without network calls or latency.
Weaknesses
  • •Extremely niche audience limited to ad tech developers working with video ads.
  • •VAST is a legacy 20-year-old format with declining relevance in some areas.
Target Audience

Ad tech developers, video engineers

Similar To

ESLint · IAB VAST Validator · XMLSpy

Post Description

I got tired of debugging VAST issues after the fact so I built vastlint.

VAST XML is how video ads get delivered on the web and on TV. It's a 20-year-old format with a 200-page spec, and broken tags are incredibly common. Most get caught in QA or post-campaign, not while writing the code. The US video ad market is around $30B a year and a lot of that leaks through errors that are honestly pretty easy to prevent.

The VS Code extension shows squiggles on the offending tag as you type, hover tooltips with what's wrong and how to fix it, and a Problems panel with file and line. 108 rules covering the full IAB VAST spec from 2.0 to 4.3.

It's on both the VS Code Marketplace and Open VSX so it works in VS Code, Cursor, Windsurf, Kiro, VSCodium, Gitpod, and Theia. The validation runs locally via WASM, no network calls.

GitHub: https://github.com/aleksUIX/vastlint VS Code Marketplace: https://marketplace.visualstudio.com/items?itemName=aleksUIX... Open VSX: https://open-vsx.org/extension/aleksUIX/vastlint

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