How to Validate Publishers in APAC: Web, App & CTV Workflow

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Validating publishers is one of the most important responsibilities for programmatic teams in APAC. Whether you work on the supply side, on a DSP, or support buyers with inventory recommendations, you need to confirm that a publisher is legitimate, offers real scale and provides authorised, brand-safe supply.

In Southeast Asia, this can be complex. Many publishers do not have consistent ads.txt files, CTV supply is fragmented across regional platforms, and emerging apps often lack complete metadata. This guide covers reliable tools and manual workflows you can use to validate both web and app/CTV publishers.

1. SimilarWeb – Traffic & Geo Validation for Websites

Best for: traffic estimates, top markets, traffic sources
Website: similarweb.com

SimilarWeb provides directional traffic and engagement signals that help you validate the scale of a website. While not perfect, it’s extremely useful for identifying publishers whose traffic claims may be exaggerated or misaligned with their pitch.

APAC teams typically look for:

  • Estimated monthly visits – does this roughly match the publisher’s media kit?
  • Top geographies – especially for SEA campaigns
  • Traffic sources – heavy referral traffic can indicate low-quality traffic
  • Engagement time – extremely low time can signal low-attention supply

2. ads.txt & app-ads.txt – Verifying Authorised Sellers (Web, App & CTV)

Best for: confirming who is authorised to sell publisher inventory

For websites, ads.txt is the source of truth for verifying authorised sellers. For apps and CTV publishers, the equivalent is app-ads.txt, which is hosted on the developer’s website and linked from the app’s store listing.

A practical manual workflow:

  • Web: Visit https://publisherdomain.com/ads.txt and check the SSP entries, seller IDs and DIRECT/RESELLER relationships.
  • App/CTV: Find the app in the Play Store or App Store → click the developer website link → append /app-ads.txt and verify authorised sellers.

If a publisher appears in programmatic supply with no ads.txt/app-ads.txt file, or if entries don’t align with your DSP/SSP logs, that’s a red flag.

3. sellers.json – Cross-Checking SSP Declarations

Best for: verifying how SSPs classify publisher relationships

sellers.json files list how SSPs represent their publishers and resellers, including relationship types (DIRECT vs RESELLER).

A simple workflow:

  • Open the SSP’s sellers.json file
  • Search for the publisher’s domain, app bundle or seller ID
  • Check that the relationship type matches what you saw in ads.txt/app-ads.txt
  • Look for unexpected intermediaries or mismatches

Discrepancies between ads.txt/app-ads.txt and sellers.json usually indicate issues that should be resolved before onboarding.

4. WHOIS – Domain Ownership & Age Checks

Best for: confirming domain age and legitimacy

WHOIS tools (ICANN Lookup, Whois.com, DomainTools) allow you to check:

  • Registration date – recently registered domains deserve closer inspection
  • Ownership – does it match the publisher’s company name?
  • History – are there recent ownership changes?

This step prevents onboarding low-trust, newly-spun-up domains posing as premium publishers.

5. BuiltWith, Wappalyzer & Ghostery – Tech Stack & Ad Infrastructure

Best for: assessing the publisher’s technical setup
Websites: builtwith.com, wappalyzer.com, ghostery.com

These tools provide visibility into how a publisher is configured:

  • Which ad server they use (e.g., GAM)
  • If a CMP or privacy solution is present
  • Which analytics tools run onsite
  • Whether SSP/ad network tags appear in the stack

Ghostery goes further by showing which scripts and trackers fire in real time. This helps confirm:

  • Whether the publisher is running legitimate ad tech
  • Unexpected trackers or suspicious tags
  • Presence of viewability/measurement tools

6. Pixalate – App & CTV Legitimacy + IVT Risk

Best for: verifying app legitimacy and invalid traffic risk
Website: pixalate.com/resources/rankings

For mobile apps and CTV channels, Pixalate provides:

  • CTV rankings across OEM platforms (Samsung, LG, Xiaomi PatchWall, etc.)
  • IVT/SIVT risk ratings for apps
  • Signals on lesser-known or emerging apps

This complements app-ads.txt checks by adding behavioural and risk-based insights.

7. A Practical Web + App Publisher Validation Workflow

A simple, repeatable workflow for APAC teams might look like:

  1. Check traffic with SimilarWeb to validate scale and markets.
  2. Use WHOIS to confirm domain age and ownership.
  3. Validate authorised sellers via ads.txt (web) and app-ads.txt (app/CTV).
  4. Cross-check sellers.json to verify SSP declarations.
  5. Review the tech stack with BuiltWith, Wappalyzer and Ghostery.
  6. For apps/CTV, validate legitimacy and IVT/SIVT risk using Pixalate + app store metadata.

Conclusion

Publisher validation in APAC requires more than a quick traffic check or a single spreadsheet. It involves combining traffic signals, ownership checks, authorised seller verification and app/CTV legitimacy assessments.

Using tools like SimilarWeb, WHOIS, ads.txt, app-ads.txt, sellers.json, BuiltWith, Wappalyzer, Ghostery and Pixalate together gives APAC programmatic teams a structured way to decide which publishers to onboard, which to exclude and how to build cleaner, more accountable supply for their buyers.

If you’d like help designing or refining a publisher validation process for your team or market, feel free to reach out. I support APAC teams on supply quality, marketplace design and curation, and can help adapt this workflow to your specific environment.