rtblint

OpenRTB linter. Validates OpenRTB 2.x bid requests and bid responses against versioned IAB Tech Lab spec snapshots, from 2.0 through the monthly 2.6 releases (currently up to 2.6-202606).

Website and playground: rtblint.org

What it checks

• Malformed JSON and wrong top-level shape
• Required fields, including required non-empty arrays
• Unknown objects and fields per version catalog (ext subtrees stay open)
• Type mismatches (string, integer, float, boolean, object, and array forms)
• Documented enum values, including AdCOM lists and vendor ranges (500+)
• Deprecated, moved, removed, and not-yet-available fields across versions
• Semantic rules: site/app/dooh exclusivity, imp media type presence, skippable video dependencies, duration exclusivity, seatbid/nbr presence on responses, and more

Every finding carries a stable rule id, a severity, a message, and a JSON path.

Surfaces

Surface	Package	Status
Rust CLI	rtblint	Working
Rust library	rtblint-core	Working
MCP server	rtblint-mcp	Working
Node (WASM)	rtblint-core on npm	Working
Python	rtblint on PyPI	Not implemented yet
Go	github.com/aleksUIX/rtblint/go	Not implemented yet

OpenRTB 3.0 payload validation is not implemented yet (the 3.0 catalog ships for introspection only). The 2.6-202204 snapshot has no extracted catalog and reports itself as unsupported instead of passing payloads silently. See ROADMAP.md for what's next and CHANGELOG.md for release history.

CLI

cargo install rtblint

rtblint validate request.json
rtblint validate --type response response.json
rtblint validate --version 2.5 --format json request.json
cat request.json | rtblint validate --stdin

Exit codes: 0 valid, 1 validation errors, 2 usage or I/O error.

Node

import { validate, validateResponse, versions } from "rtblint-core";

const report = validate(JSON.stringify(bidRequest), "2.6-202505");
if (!report.valid) {
  for (const issue of report.issues) {
    console.log(`[${issue.severity}] ${issue.path}: ${issue.message} (${issue.id})`);
  }
}

MCP server

rtblint-mcp speaks MCP over stdio and exposes validate_bid_request, validate_bid_response, and list_openrtb_versions.

{
  "mcpServers": {
    "rtblint": { "command": "rtblint-mcp" }
  }
}

Rust library

use rtblint_core::{validate_bid_request_for_version, OpenRtbVersion};

let result = validate_bid_request_for_version(OpenRtbVersion::V2_6_202505, payload);
for issue in &result.issues {
    println!("{} {} {:?}", issue.severity, issue.id, issue.path);
}

Spec data and provenance

The validator runs on structured catalogs extracted from the IAB Tech Lab OpenRTB specifications: object names, field names, type notations, enumerated value sets, and section citations. The catalogs carry no spec prose. rtblint is not affiliated with or endorsed by IAB Tech Lab. See NOTICE for attribution.

License

Apache-2.0. See LICENSE and NOTICE.