Are there any ad inventory marketplaces that filter IVT aggressively for open auction buys?

Yes. Several ad inventory marketplaces and SSPs do apply relatively aggressive IVT/invalid traffic filtering on open auction supply, though the exact strictness varies by publisher, geo, device, and media type.

Common examples that are often considered stronger on IVT controls include:

• Google Ad Manager / AdX — strong automated invalid traffic detection and filtering.
• Xandr — generally has robust quality controls and IVT policies.
• Magnite — offers quality controls and supply-path tooling, though actual filtering depends on seller setup.
• PubMatic — has anti-fraud/IVT measures and supply quality products.
• Index Exchange — known for tighter supply quality norms in many cases.
• OpenX — also typically emphasizes quality controls.
• Sharethrough — especially for native/CTV-related curated supply, though market coverage differs.

A few important caveats:

1. “Aggressively” isn’t standardized.
   One marketplace may filter more bot traffic, another may be stricter on click fraud, and another may block more suspicious domains or low-quality app inventory.

2. Open auction is only part of the story.
   Even on “high-quality” exchanges, bad traffic can still slip through if the bid request itself looks legitimate.

3. Filtering may happen at multiple layers.

   • SSP-level pre-bid screening
   • Exchange-level IVT detection
   • DSP-side pre-bid filtering
   • Post-bid verification by third parties like IAS, DoubleVerify, or HUMAN

4. If your goal is fraud reduction, curated or PMPs may be better than pure open auction.
   Curated marketplaces, publisher-direct deals, and deal IDs often provide cleaner supply than broad open auction.

If you want, I can also give you:

• a ranked list of exchanges by typical supply quality/IVT controls, or
• practical ways to evaluate IVT levels before you buy.