Independent AI ad
networks: what a US business can buy,
and whose apps the files confirm

Gravity, Koah, Thrad, Kontext and Velocity are five of the independent networks that sell ads inside AI apps other companies run. As of September 25, 2026, a US business can sign up on its own with Gravity, Thrad and Koah. Gravity and Thrad document targeting by country, including the US. Koah publishes no country rule. Kontext takes advertisers by email, and PubMatic announced curated deals for its inventory in December 2025. Velocity takes inquiries only through a contact form.

Whose apps they can be shown to sell is a short list. Digital Traction matched each network’s line in the publishers’ own ads.txt files against the network’s sellers.json on September 25, 2026. By that check, Thrad is confirmed for one app, DeepAI. Kontext is confirmed for four: PolyBuzz, SpicyChat, Chai and Saylo. Velocity matches 14 of its 30 seller accounts, a mix of AI apps and open-web sites such as radaronline.com. Koah’s line fails the check, and Gravity publishes nothing to check.

A match shows that both sides declare a relationship. It does not show that ads were delivered, how many, or that the traffic was valid. Several of the same apps are also sold through ordinary ad exchanges, which matters to a business that already buys through a demand-side platform (DSP).

Which networks a US business can buy today

Each network sets its own way in. The record below answers the US question first, then gives the result of the file check described in the next section. Each network’s buying route and the measurement it describes are also set side by side on the Advertising in AI page.

Gravity’s quickstart starts at its advertiser sign-up page and asks for an email and a company name (Gravity quickstart), and its geo targeting takes “Country codes (US, GB, CA)” (Gravity campaigns). Koah said on February 3, 2026, that advertisers can accept its agreement directly in the app, “Sign up, agree, and go” (Koah changelog). Its advertiser page offers a demo booking and a login (Koah).

Thrad sells through a self-serve platform, and its docs say “Thrad campaigns are targeted by country” (campaign targeting). A DSP can also bid in its real-time auctions. The sample bid request in Thrad’s DSP onboarding guide carries the chat itself, with messages from both the user and the assistant.

Kontext asks advertisers to email advertisers@kontext.so to be set up (Kontext docs). On December 9, 2025, PubMatic announced curated private marketplace deals for Kontext’s inventory and invited “select advertisers and agencies” to early testing (PubMatic). No newer status was found. Velocity’s advertiser page sends its “Get started” button to a contact form (Velocity).

Two established ad companies have also announced AI placements. Taboola announced an ad platform for AI chatbots and assistants on June 16, 2026, with demand from Realize, its existing ad platform. adMarketplace’s AI Discover beta was announced on April 28, 2026 to run from June to December 2026, with the United States among its first markets. Both are the companies’ own announcements, and neither was checked against files here.

How to check a network’s supply

Two public files, both defined by IAB Tech Lab, show which apps a network may sell:

• ads.txt sits on the publisher’s own domain. Each line names an advertising system allowed to sell the publisher’s inventory, the publisher’s account ID there, and the relationship (ads.txt 1.1). Apps publish the same lines as app-ads.txt on the developer’s website (app-ads.txt 1.0).
• sellers.json sits on the advertising system’s own domain, at /sellers.json, and lists the accounts it sells for (sellers.json 1.0).

In ads.txt, DIRECT means the publisher “directly controls the account” on that system. RESELLER means the publisher “has authorized another entity to control the account” and resell its ad space. In sellers.json, PUBLISHER means the named company owns the inventory and is paid directly by the advertising system. INTERMEDIARY means it does not own the inventory or is not paid directly.

1. Open the publisher’s ads.txt at its root domain, or app-ads.txt on the app developer’s website, and find the network’s line.
2. Note the domain that line names and the account ID.
3. Open the sellers.json at that exact domain and look for the same ID.
4. Write down the date. Either file can change at any time.

Two details decided four of the failures below. The specification says the sellers.json should sit at the domain the line names, not at a related host. And a line on a subdomain counts only when the root domain’s ads.txt declares that subdomain. Otherwise, under section 5.5 of ads.txt 1.1, only the systems in the root file are authorized.

Whose apps the files confirm for each network

Thrad

Thrad’s sellers.json lists one publisher, DeepAI, and DeepAI’s ads.txt names Thrad with the same ID on line 4. That is the whole list, although Thrad’s publisher docs tell every publisher to add a thrad.ai line, because “Ad buyers check your ads.txt before they bid.”

Kontext

Kontext’s publishers name megabrain.co in their lines. The sellers.json at megabrain.co, last updated September 11, 2025, lists four apps, and each one matches: PolyBuzz, SpicyChat, Chai and Saylo. Liner and Moescape carry megabrain.co lines too, but their IDs appear only in kontext.so/sellers.json, a domain no line names, so both fail. Kontext’s own ads.txt guide calls the line “a hard requirement for ramping up fill rate.”

Velocity

Velocity’s sellers.json lists 70 domain entries under 30 seller IDs. It carries no update date, and it gained an entry during the day of the check. Checking each domain’s root ads.txt and app-ads.txt, 14 of the 30 accounts match. The AI apps among them:

• DeepAI, HubX (aiapp.org) and Leadtech (getaichat.app)
• AIBY, the developer of ChatOn (AIBY’s app-ads.txt), Taze and AI Hay
• Jetkite, Kolbo.ai, Smry.ai and EcoGPT

The other matches are not AI apps: ndtv.com under a seller named Whtvr, 14 sites under a seller named Inline, among them radaronline.com and okmagazine.com, plus ovivogames.com and pointcoin.app (seller Multify). Nine of the file’s 30 seller IDs appear more than once, Inline’s 22 times and Whtvr’s 11. The sellers.json specification says a seller ID may not represent more than one entity, and IAB Tech Lab’s 2021 validation guide flags any repeated seller ID.

Liner shows how the subdomain rule works. Its Velocity line sits on app.liner.com/ads.txt, but liner.com’s root file declares no subdomain, so only the root file counts, and it has no Velocity line. Liner fails for Velocity as it does for Kontext.

Koah

DeepAI’s ads.txt names koahlabs.com on line 3, but koahlabs.com/sellers.json returned a 404 page. The same ID is listed as DeepAI at app.koahlabs.com/sellers.json, a host no line names. By the rule, the line fails.

Gravity

No Gravity line appears in any file fetched, and Gravity publishes no sellers.json. One publisher explains why in its own file: “Gravity and Koah are direct first-party SDK integrations, not programmatic resellers” (smry.ai’s ads.txt, checked September 25, 2026). The file check cannot see supply that runs only through an SDK.

Where the same apps are resold

Other lines in the same files show a second way into several of these apps: exchanges that a DSP may already connect to. Each route below is declared on both sides.

• Koah through PubMatic. DeepAI’s first line authorizes PubMatic account 167410 as RESELLER, and PubMatic’s sellers.json lists 167410 as Koah Labs, an intermediary.
• Kontext through PubMatic. PubMatic lists account 167306 as Kontext, under megabrain.co. Liner, Chai, Saylo and PolyBuzz authorize it as RESELLER, which is consistent with the route PubMatic announced in December 2025.
• Kontext’s own accounts, marked DIRECT. InMobi, SmartyAds and Rise each list an account in Kontext’s name. PolyBuzz, SpicyChat, Moescape, Liner and Saylo declare those accounts DIRECT, a label the specification uses for an account the publisher itself controls.
• Thrad through bidline.net. DeepAI lists a bidline.net account as direct, and bidline.net’s sellers.json names that account’s seller as Thrad.ai, not DeepAI.
• Velocity through Rise, and often Sharethrough. In most of the AI apps’ files, Velocity’s line is followed by a Rise account that Rise lists as Velocity.io, and often by a Sharethrough account that Sharethrough lists as Rise’s in-app exchange. Velocity’s advertiser page promises “Direct access to AI-native apps,” a vendor claim.

Beyond the networks, all 10 AI-app files counted authorize PubMatic, Magnite, OpenX and Xandr as resellers, and Google appears in 6 of them. None of the files says which ad format those routes carry, so a DSP buy may reach the app without reaching the placement inside the chat.

Some network consoles also run ChatGPT campaigns. Thrad’s reporting numbers “combine Thrad and ChatGPT (OpenAI Ads) supply by default” (Thrad insights), and Gravity’s reporting API notes the time zone OpenAI’s reporting uses for ChatGPT campaigns. That is not resale of app supply. Gravity’s docs refer to “OpenAI ad accounts,” and OpenAI’s guide for API partners says to “Use the API key associated with the client ad account for every request” (OpenAI), which points to these campaigns sitting in an OpenAI ad account. Whose account it is, neither network’s docs say. Buying ChatGPT ads directly, and the account rules that apply, are covered in ChatGPT ads: what a US business can buy today.

What the networks do not publish

• Delivery by app. No network’s public advertiser documentation offers a report by app. Thrad’s reporting API breaks results down by source, country and device only, and “Any other value returns invalid_segment.” Gravity’s API returns ad-group series “summed across publishers,” although its dashboard shows “Top-performing publishers and conversation topics.” Velocity’s documentation sits behind a login, and its advertiser page promises “full visibility into performance and where your ads run,” a vendor claim.
• A publisher list. Gravity has no sellers.json, and Koah has none at the domain its line names.
• A current file at the named domain. The megabrain.co file that Kontext’s lines name was last updated September 11, 2025, while its newer May 12, 2026 file sits at kontext.so. Velocity’s and Thrad’s files carry no date, which the specification does not require.
• A self-serve route for Velocity. Its advertiser page leads to a contact form.
• The format sold through reseller accounts, from any network.
• An independent audit of delivery, from any network.

The last two come from absence: no such page was found on September 25, 2026.

What to check before buying

For a US business weighing a first test, the checks are short and public:

1. Confirm the route and the country. Find the sign-up page or the named contact, and check that campaigns can target the US.
2. Ask the network for its publisher list, then open each publisher’s ads.txt or app-ads.txt at the root domain.
3. Match each line’s ID in the sellers.json at the domain the line names, and write down the date.
4. Read the relationship. DIRECT should mean the publisher controls the account. If the exchange’s sellers.json names the network as the seller, ask why the line says DIRECT.
5. Ask whether the business’s own DSP already reaches the same apps through PubMatic, Magnite, OpenX or Xandr, and which format that route sells.
6. Ask for delivery by app. No network’s public advertiser API offers it.
7. For ChatGPT campaigns run through a network’s console, ask whose OpenAI ad account the campaign sits in.
8. Check the files again before each test. They change without notice.

About this guide

Every file named here was fetched on September 25, 2026, between 10:23 and 11:05 p.m. US Eastern, and every match is as of then. The files change without notice: Velocity’s sellers.json gained an entry that same day. Koah’s files at koah.ai and app.koah.ai, the domain PubMatic lists for Koah, returned 403 to the check and were not read. A match shows that both sides declare a relationship. It does not show that ads ran, how many, or that the traffic was valid. The networks’ documentation is their own, and claims about reach are labeled as vendor claims in the source notes.