On August 31, the European Commission designated ChatGPT a “Very Large Online Search Engine” under the Digital Services Act — the same regulatory bracket Google Search has carried for years. The trigger was OpenAI’s own disclosure: 159.1 million average monthly users across the EU, more than three times the 45 million threshold that defines “very large.” Reddit and Roblox were designated Very Large Online Platforms the same day.
The numbers in this piece
01What the Commission actually did
- The designation is capability-based, not category-based. The Commission’s own language: ChatGPT qualifies because it “responds to users’ prompts and queries, including by searching the web” — the live web-search function is what triggers VLOSE status, not the chatbot product as a whole.
- The number came from OpenAI itself. The 159.1 million figure is OpenAI’s own DSA transparency disclosure, covering the six months ending March 31, 2026 — self-reported, as every platform’s threshold figure is under this regime.
- Reddit and Roblox got the platform version of the same label (Very Large Online Platform, not Search Engine), each also self-reporting past 45 million average monthly EU users.
- The compliance clock is four months from notification — by January 2027, per the Commission — covering systemic-risk assessments, independent audits, and data access for regulators and vetted researchers.
02What it means inside a GAM network
The obligation that matters to an ad-tech operator isn’t the audit regime — it’s the public ad repository. Once a service crosses into “very large” status and runs ads, DSA rules require every ad shown to EU users to be logged in a public, queryable repository: creative, targeting parameters, who paid for it — the same transparency layer Google and Meta have carried for years. ChatGPT’s ad business crossed a $1 billion run rate and opened self-serve access across Europe this same week (APH, September 1); the campaigns landing through that new self-serve door will be the first ChatGPT ads to run under full DSA ad-transparency rules from day one, not retrofitted onto an established business.
03What publishers and buyers should do
04The bottom line
Brussels didn’t rule that ChatGPT is a search engine in the everyday sense — it ruled that 159.1 million EU users searching the web through it is enough to trigger search-engine-grade oversight, the same 45 million-user bar that already governs Google. For a business that just told the market it’s scaling ad revenue fast, the timing puts its youngest ad campaigns under its strictest transparency regime first.
Search Engine Journal, “ChatGPT Is Now A ‘Very Large Online Search Engine’ In The EU” (31 August–1 September 2026), for the 159.1 million EU MAU figure, its OpenAI-disclosure sourcing, the designation date, and the public ad repository detail. European Commission, “Commission designates ChatGPT, Reddit, Roblox under Digital Services Act” (31 August 2026), for the VLOSE/VLOP designation split, the 45 million threshold, and the four-month/January 2027 compliance deadline. The publisher/GAM operator analysis is APH desk analysis.