Kokai is the buying platform of The Trade Desk, the largest independent demand-side platform (DSP), meaning the software advertisers and agencies use to buy digital ad impressions automatically across many publishers. It is both the screen a trader logs into and the machine learning layer that decides which impressions to bid on and at what price. Kokai exists because The Trade Desk wanted to move buying decisions away from manual rules set by traders and towards predictions made impression by impression. It replaced the previous platform, Solimar, and by February 2026 the company said almost all of its clients were running through it.

How Kokai works

When a person opens a web page, app or streaming channel, a supply-side platform (SSP) sends a bid request describing the impression: site or app, device, location, ad format and any user identifiers. Connected DSPs have milliseconds to decide whether to bid. The Trade Desk said at launch in 2023 that Kokai evaluated more than 13 million impressions a second, each carrying potentially thousands of signals. Jeff Green, the company's co-founder and chief executive, put the figure at 20 million impression opportunities a second in March 2026, with bidding decisions taking 10 milliseconds or less.

Kokai's distinguishing idea is what The Trade Desk calls distributed AI: deep learning models placed at several points of the buying process rather than in a single optimisation engine. The launch release of June 6, 2023 listed the main ones. Predictive bid clearing estimates the lowest price likely to win an auction. Relevance scoring rates each impression against a campaign's goals. Budget optimisation, key performance indicator (KPI) scoring and forecasting complete the set.

The models run on top of Koa, the artificial intelligence The Trade Desk introduced in 2018 to help set up and optimise campaigns. Koa remains the name of the optimisation layer inside Kokai, which makes the two easy to confuse. Kokai is the platform; Koa is the AI working inside it.

Seeds and relevance

A typical Kokai campaign starts with a seed. A seed is a set of people the advertiser regards as its most valuable customers, ideally built from first-party data such as customer relationship management (CRM) uploads, website pixel conversions or retail purchase data. Kokai compares the audience a trader is targeting with that seed and shows a relevance score, a forecast of how closely the targeting matches the seed, according to a June 21, 2024 guide published by The Trade Desk.

Controls and trading modes

Traders still set budgets, frequency caps, inventory lists and deal priorities, but more is now left to the models. In September 2025 The Trade Desk introduced the Koa Adaptive Trading Modes, splitting buying into a Performance Mode, in which the platform automates more decisions, and a Control Mode, in which traders keep more manual settings. Third-party data through Audience Unlimited cost 3.3% or 4.4% of impression costs in Control Mode and nothing extra in Performance Mode. In the second quarter of 2026, the on/off switch for Koa optimisations was replaced with three modes covering performance and delivery, efficiency, and allocation of spend by priority. Koa stays on by default.

What else lives inside Kokai

Several products sold under their own names are, in practice, sections of Kokai. Deal Desk, launched on June 9, 2025 as "a new pillar" of the platform, centralises private marketplace and programmatic guaranteed deals and assigns each a Deal Quality Score. The Trade Desk's internal analysis found that roughly 90% of deal IDs failed to scale. Inventory Controls draw on publisher metadata from Sincera, a supply-chain data company The Trade Desk acquired in January 2025, covering more than 400,000 publishers. Measurement draws on three indexes launched with Kokai: Retail Sales, TV Quality and Quality Reach.

Origin and evolution

Kokai is the third generation of The Trade Desk's buying interface in five years. Solimar launched in July 2021 after more than two years of development. Less than two years later, on June 6, 2023, the company presented Kokai at an event in New York.

Its most visible feature was the Programmatic Table, a navigation layout modelled on the periodic table of elements. The Trade Desk has not set out the origin of the name Kokai in the material reviewed for this article.

Adoption was slow. Through 2024 buyers could choose between Solimar and Kokai, and many stayed on the older interface. After a December 2024 reorganisation into about 100 scrum teams, the company reported on February 12, 2025 fourth-quarter 2024 revenue of $741 million, below its own guidance, and Green acknowledged problems in the transition. Bill Simmons, a former vice-president of product, said on March 14, 2025 that he had left the company days after critics questioned Kokai, calling the platform "a bold, fundamental reinvention of what a DSP can be."

The company then pushed. More than 70% of client spend was flowing through Kokai by the second quarter of 2025. From August 13, 2025, media buyers reported Solimar prompting them to create all new campaigns in Kokai, with full migration targeted for the end of 2025. Accounts of the cut-off differ: Adweek reported on November 20, 2025 that new Solimar campaigns had just been blocked, despite "assurances" one agency said it had received. By late 2025 nearly 85% of clients were on Kokai by default; on February 25, 2026 the company said "almost 100%" were.

The interface was revised along the way. In September 2025 The Trade Desk said it would keep the periodic table only at ad group level, removing it from advertiser and campaign views. On August 27, 2026 it released Kokai Zuma, which dropped the table as the default view in favour of an "applied settings" view, according to Adweek. Zuma also put Koa Assistant, a conversational tool backed by specialised agents, into closed beta. The company reported an average 32% improvement in cost per acquisition (CPA) from Zuma's upgraded modelling; PPC Land's reporting tied the figure to 62 campaigns.

Why it matters to marketers

For agencies and brands on the open internet, Kokai determines how most independent DSP spend is bought. The Trade Desk reported full-year 2025 revenue of $2.9 billion, and its 2024 gross spend was about $12 billion. Changes inside Kokai shift how much open-web money reaches publishers, connected TV (CTV) and retail media.

The Trade Desk built its position on the claim that a DSP owning no media buys more transparently than Google, Amazon or Meta. Kokai is where that claim is tested: which fees appear, which settings stay manual and how much optimisation can be explained. The second-quarter 2026 release, for instance, added three Koa optimisation modes, CTV pause ads and Deal Desk upgrades. In July 2026, Netflix opened its inventory to Kokai buyers through the Sellers and Publishers 500+ marketplace with no spend minimum.

Limitations and criticisms

Criticism has focused on usability, control and cost. Media buyers described the interface as overloaded and the periodic table menu as unintuitive. One trader reported dropped conversions and higher cost per mille (CPM) after moving campaigns. An agency told AdExchanger in 2025 that it was moving spend towards Display & Video 360 and Yahoo for 2026 for reasons of functionality and trader efficiency rather than price.

Samantha Ross, senior director of product marketing at The Trade Desk, summarised the feedback at the Zuma launch: "users appreciate the power of Kokai, but they want it to be easier to use," according to Digiday. Dominic Johnson of Collective Measures told Digiday that the company "seems to still be playing catch up in terms of their AI features."

Fee transparency is a separate dispute that reaches Kokai indirectly. In March 2026 Publicis said an audit had found The Trade Desk did not pass and advised clients against the platform; The Trade Desk denied failing any audit, and the parties resolved the dispute by mid-June 2026. Dentsu and WPP reportedly left the OpenPath supply programme in February 2026 over similar concerns. The company does not disclose its take rate, which reporting places between 12% and 15%. The 32% Zuma figure has not been independently verified.

  • Koa: the AI introduced in 2018 that predates Kokai and now runs inside it as the optimisation and assistant layer. Kokai is the platform; Koa is the intelligence within it.
  • Solimar: Kokai's predecessor, launched in July 2021 and phased out for new campaigns during 2025.
  • OpenPath and Ventura: OpenPath is a direct supply path between The Trade Desk and publishers, charging publishers a flat 4.5% fee; Ventura is a streaming TV operating system. Both connect to Kokai but are not part of the buying interface.
  • Kokai Zuma: a named release of Kokai, shipped in August 2026, not a separate product.
  • Kōkai in Japanese: romanised as "koukai" or "kōkai," the word 航海 means a sea voyage. It has no link to the ad tech product beyond spelling.

Recent developments

The platform's latest phase is agentic. Green confirmed in March 2026 a closed beta letting advertisers build Kokai campaigns through Anthropic's Claude. Digiday reported in August that external AI tools would gain access to Kokai's agents.

The commercial backdrop has darkened. Second-quarter 2026 revenue rose 3% to $715 million, and Green told analysts on August 6 that budget-squeezed advertisers were shifting towards guaranteed buying as rivals wrap deals in agentic tools at far lower fees. On September 3, 2026 The Trade Desk cut about 15% of its workforce, roughly 575 roles. On September 21 it left the S&P 500 for the S&P SmallCap 600. As of October 2026 every client is on Kokai, and the question has moved from adoption to whether agents built on it can keep spend on the platform.

Timeline

  • 2018 - The Trade Desk introduces Koa, its AI for campaign setup and optimisation.
  • July 2021 - Solimar launches as the company's new trading platform.
  • June 6, 2023 - Kokai launches in New York with distributed AI, the Programmatic Table, new indexes and a Partner Portal.
  • June 21, 2024 - The Trade Desk publishes guidance on seeds and relevance scores in Kokai.
  • December 2024 - Company reorganises into about 100 scrum teams.
  • January 2025 - The Trade Desk agrees to acquire Sincera.
  • February 12, 2025 - Fourth-quarter 2024 revenue of $741 million misses guidance; Kokai transition problems acknowledged.
  • March 14, 2025 - Former VP of product Bill Simmons announces his departure.
  • June 9, 2025 - Deal Desk launches as a pillar of Kokai.
  • Q2 2025 - More than 70% of client spend runs through Kokai.
  • August 13, 2025 - Buyers report Solimar directing new campaigns to Kokai.
  • September 2025 - Periodic table limited to ad group level; Koa Adaptive Trading Modes and Audience Unlimited announced.
  • November 20, 2025 - Adweek reports new campaign creation in Solimar blocked.
  • February 25, 2026 - Company says almost 100% of clients run through Kokai.
  • March 4, 2026 - OpenTTD partner framework launches.
  • March 2026 - Closed beta of Claude-built Kokai campaigns disclosed; Publicis fee dispute begins.
  • April 30, 2026 - Three Koa optimisation modes enter closed beta.
  • May 12, 2026 - CTV pause ads enter open beta in Kokai.
  • June 2026 - Publicis dispute resolved.
  • July 20, 2026 - Netflix inventory opens to all Kokai buyers via Sellers and Publishers 500+.
  • August 27, 2026 - Kokai Zuma released with Koa Assistant and applied settings view.
  • September 3-4, 2026 - About 15% of staff cut.
  • September 21, 2026 - The Trade Desk moves from the S&P 500 to the S&P SmallCap 600.

Summary

Who: The Trade Desk, the Ventura, California-based independent DSP led by Jeff Green, built and operates Kokai. Agency traders and in-house advertisers use it on the buy side; publishers and SSPs supply inventory and deals into it.

What: The Trade Desk's buying platform, combining a campaign interface with machine learning models, branded Koa, that score and price individual impressions across display, video, audio, CTV and retail media.

When: Launched on June 6, 2023, made mandatory for new campaigns during 2025, used by almost all clients from February 2026, and updated with the Zuma release on August 27, 2026.

Where: The open internet, meaning ad inventory outside the walled gardens of Google, Meta and Amazon, accessed globally through The Trade Desk's web interface, APIs and, increasingly, AI agents.

Why: To replace manual, rule-based buying with impression-level predictions about relevance and price, and to give The Trade Desk an AI-based case for independent buying against platforms that own both media and data.