vastlint - IAB XML VAST validator and linter

vastlint - IAB XML VAST validator and linter

VAST XML validation MCP server for programmatic video advertising. Over $30 billion in annual CTV and video ad spend flows through VAST XML — malformed tags cause lost impressions, broken tracking, and revenue discrepancies between platforms. Validates VAST tags against IAB Tech Lab VAST 2.0, 3.0, 4.0, 4.1, 4.2, and 4.3 specifications, W3C XML 1.0 well-formedness, RFC 3986 URI syntax, IANA media types, ISO 4217 currency codes, Ad-ID registry format, and IAB SIMID 1.0–1.2. 118 rules covering required fields, schema validation, structural correctness, security, deprecated features, and value formats. Tools: validate_vast (validate inline XML), validate_vast_url (fetch and validate a VAST URL, following wrapper chains), list_rules (browse all 118 rules), explain_rule (get fix guidance for a specific rule), fix_vast (auto-fix common issues). Built on a zero-dependency Rust core. Sub-millisecond latency. No data retention — VAST XML is validated ephemerally and never stored. Self-hostabl