In-App Advertising Transparency in 2025: App-ads.txt, Sellers.json, and beyond

The programmatic supply chain has never been more complex or more scrutinized. While spend keeps climbing (over $180 billion in the US this year), 97% of users from our 2025 survey said they need more transparency with how their data is used and handled. That trust gap is the real challenge of in-app advertising today, and it’s why standards like app-ads.txt and the SupplyChain object matter more than ever.

Five years ago, tools like app-ads.txt, sellers.json, and the OpenRTB SupplyChain object were new initiatives just starting to gain traction. Today, they’ve become industry standards. But fraud tactics have evolved, regulations have tightened, and advertisers now demand greater control over their supply chains. Let’s look at how transparency solutions have matured and what challenges remain in 2025.

App-ads.txt: From optional to essential

Who implements it? Publishers
Who benefits? Advertisers and publishers alike

The app-ads.txt specification, introduced by IAB Tech Lab in 2019, is now a baseline requirement for legitimate publishers. 66% of the top 1,000 Google Play apps have adopted app-ads.txt (versus a 24% overall adoption rate).

App-ads.txt helps eliminate spoofed apps and unauthorized resellers by allowing publishers to publicly list approved monetization partners (e.g., www.publishername.com/app-ads.txt). DSPs and advertisers can crawl this file to verify sellers and avoid fraudulent inventory.

The remaining challenge in 2025 is maintenance. Outdated or incomplete files continue to cause lost revenue opportunities for publishers and wasted spend for advertisers. For publishers, keeping app-ads.txt accurate and current is a competitive necessity.

Sellers.json and the OpenRTB SupplyChain Object

Who implements them? SSPs, exchanges, and intermediaries
Who benefits? Buyers (visibility), intermediaries (trust)

Launched shortly after app-ads.txt, sellers.json and the OpenRTB SupplyChain object closed the loop on transparency.

• Sellers.json: Intermediaries publicly disclose the publishers they represent in a .json file.
• SupplyChain object: Tracks every seller and reseller involved in an impression, giving advertisers full visibility into the transaction path.

In 2025, these tools are core to supply path optimization (SPO). Advertisers use them to identify the most direct, cost-efficient, and trusted supply routes by cutting out unnecessary hops, lowering fees, and reducing fraud exposure. Many brands now mandate SPO audits and clean supply commitments from partners.

Transparency in 2025

What started over five years ago with app-ads.txt and sellers.json is no longer optional. It’s become the industry baseline. By now, adoption across major publishers and intermediaries is widespread, and buyers expect these signals before spending.

But transparency hasn’t stopped there. Today, AI-powered verification and machine learning fraud detection have added an extra layer of protection, spotting invalid traffic patterns and spoofed inventory at speeds humans can’t match. Combined with SPO, these tools are giving advertisers more confidence that their spend is reaching real audiences through legitimate channels.

The result: transparency is no longer a “nice-to-have.” It’s the minimum requirement for participation in the programmatic ecosystem. The differentiation now lies in how effectively companies build on this baseline. That can be by pairing these standards with stronger reporting, offering clearer value exchange to consumers, or investing in privacy-first infrastructure.

Learn more

Download our 2025 In-App User Privacy Report for deeper insights into fraud, transparency, and consumer trust.