OpenDirect is an application programming interface (API) specification, maintained by IAB Tech Lab, that lets a buyer search a publisher's catalogue of advertising products, check price and availability, place an order, attach creative and book guaranteed inventory, all through software rather than email, spreadsheets and phone calls. It exists because the direct sale of reserved ad space, the part of the market built on insertion orders, stayed manual long after auctions were automated. Every publisher's order system differed, so each buyer integration was custom; OpenDirect proposed one interface for all of them. The current version, as of October 2026, is 2.1.

How an OpenDirect transaction works

The specification describes a RESTful API, authenticated with OAuth, that a publisher or its vendor exposes and a buying platform calls, in four steps.

First, the relationship. A buyer must obtain an organization ID from the publisher before it can trade, and an agency acting for a brand must hold formal consent from that advertiser and be able to prove it. The publisher then creates an account tying buyer and advertiser together. Second, discovery. The buyer queries /products, posts searches to /products/search and asks for availability and pricing at /products/avails. A Product can be a single placement or a run-of-network package, and carries a base price, currency, rate type, estimated daily availability, minimum spend, minimum and maximum flight lengths and a lead time in days.

Third, the order. The buyer creates an Order under its account, with a currency, a directional budget and start and end dates, and adds Lines, one per product. Each line carries the requested quantity (qty), a rate, a projected cost and optional frequency caps. Five rate types are allowed: cost per thousand impressions (CPM), cost per thousand viewable impressions (CPMV), cost per click (CPC), cost per day (CPD) and flat rate. Fourth, creative and booking. Creative is uploaded to the account and attached to lines through an Assignment object, which in version 2.1 sets each creative's share of voice. The buyer then calls ?reserve or ?book.

A line moves through a defined set of booking statuses: Draft, PendingReservation, Reserved, PendingBooking, Booked, InFlight, Finished, Stopped, Canceled, Pause, Expired, Declined and ChangePending. A worked example shows the logic. A buyer asks for 500,000 impressions on a homepage product at a $12 CPM for two weeks. If the publisher's forecast cannot cover the quantity, the specification requires the reservation to fail and the line to be marked Declined. If it can, the line is Reserved until its expiry time, then Booked, at which point the projected cost is $6,000 and the publisher's ad server delivers it at the same priority as any other direct campaign. Changes after booking go through a ChangeRequest, which the seller approves or rejects, and line-level reporting comes back through a Stats object.

OpenDirect therefore sits before delivery. It replaces the request for proposal (RFP), the insertion order and manual trafficking, and carries no bids.

From a four-company working group to version 2.1

In June 2013, AOL, Yahoo, Microsoft and Yieldex formed a working group to standardise the automated sale of reserved inventory, a model the trade was then calling programmatic direct or automated guaranteed. Bionic Advertising Systems and MediaMath joined later, and the group handed the work to the Interactive Advertising Bureau (IAB) and its Digital Advertising Automation Task Force.

The IAB released OpenDirect 1.0 for public comment on November 3, 2014, at its Ad Operations Summit, with comments open until December 3. "OpenDirect 1.0 is valuable to the industry at-large and therefore is best served under the auspices of the IAB," said Scott Cunningham, then vice president of technology and ad operations at the IAB, according to the announcement. The final 1.0 followed in January 2015.

Version 1.5, released in March 2016, was described by IAB Tech Lab as the first major update. It added multiple currencies, publisher-created orders, change requests for orders in flight and booking before creative was assigned.

Version 2.0 changed the architecture. IAB Tech Lab released it for public comment in January 2018, with feedback due by March 12. It adopted the Advertising Common Object Model (AdCOM), the shared vocabulary for sites, placements and ads that IAB Tech Lab also uses in OpenRTB, extending OpenDirect beyond display to video and out-of-home, and added a messaging object so buyers and sellers could negotiate inside the API. "This update to OpenDirect will allow for more fluid movement of premium inventory," Dennis Buchheim, then general manager of IAB Tech Lab, said at the time. Robyn Parker of Adslot, co-chair of the working group, described automated guaranteed as "automation of the insertion order process," according to MarTech. A final 2.0 was dated February 13, 2019, according to Kochava, whose XCHNG platform claimed the first implementation; IAB Tech Lab's version table gives no date.

Physical media and the 2.1 rewrite

The most recent revision came from outdoor advertising rather than the web. The Out of Home Advertising Association of America (OAAA) released an OpenDirect 1.5.1 in May 2021, with contributions from Clear Channel, JCDecaux, Kinetic, Ocean Outdoor and others. Ian Dallimore of Lamar Advertising, who co-chaired the effort, described the status quo bluntly: "Currently the exchange of excel documents between vendors and agencies is how inventory and availability is shared." The spec file in the GitHub repository is nonetheless headed "Released March 2016," an inconsistency in the record.

Version 2.1 generalised that work. Its new ProductTargeting object recognises that physical media is sold by frame, location, time and share of time rather than by impression. A buyer can target frames that see an audience, or an audience that sees frames, and buy on fixed, per-frame or cost-per-thousand pricing. Availability responses now say whether inventory is Available, Partially Available or Unavailable, with 13 coded reasons, from Booked and Optioned to ClientDuplication and LocationDuplication. The Stats object gained proof-of-play fields: spot start and end times with time-zone offsets, spot length in milliseconds and share of time.

The release date depends on the source. The repository's tag is labelled 202407 and IAB Tech Lab's standards page reads "last updated July 8, 2024", but the 2.1 commit was reverted the same day and only restored on September 19, 2024. Outdoor trade bodies in the United States, Australia and the United Kingdom announced it in late September 2024.

Why it matters to marketers

For most of its life, OpenDirect mattered more as an idea than as plumbing. The market for guaranteed programmatic buying grew mainly through a different mechanism: a deal agreed in a platform, then executed through deal IDs in OpenRTB bid requests, as with the Programmatic Guaranteed product Google opened in public beta in January 2016. Automating the conversation before the deal, OpenDirect's job, never reached comparable scale.

That has changed with AI agents. When IAB Tech Lab set out its agentic roadmap on January 6, 2026, it chose to extend OpenDirect, OpenRTB, AdCOM, VAST and the Deals API rather than write new standards. Its reference seller agent is built on OpenDirect 2.1, and the Kochava workspace that put the Agentic Advertising Management Protocols (AAMP) into open beta in March 2026 turns campaign briefs into OpenDirect bookings. A buyer agent needs what OpenDirect describes: a catalogue, an availability call and a booking endpoint. Adform's chief technology officer estimated a custom deals integration with one supply-side platform at 250 to 350 days of work, against roughly 50 on a shared standard.

Limitations and disputes

Adoption is the central weakness, and the specification concedes it. The 2.1 text says that "a handful of companies have already started adopting the API" and that "more features are needed to encourage wider adoption". IAB Tech Lab publishes no implementation count.

The reasons were identified early. In September 2014, Vedant Sampath of Mediaocean wrote in AdExchanger that the barriers were "entrenched processes and a lack of trust between the buyer and the seller", with publishers fearing commoditisation and agencies doubting fair pricing without RFP pressure. Managing separate credentials with every publisher, which the spec required, was another early complaint.

Maintenance is uneven. The 2.1 document still lists AppNexus, Moat and Telaria among IAB Tech Lab's board members and mentions DigiTrust, all names that have since disappeared from the market. The specification also states that it "does not directly enable improved impression counting between parties," leaving discrepancy disputes to the ad servers.

What OpenDirect is not

Programmatic guaranteed is a transaction type: fixed price, reserved volume, executed programmatically. OpenDirect is one way to agree and book such a deal; most programmatic guaranteed volume runs without it.

OpenRTB is the real-time bidding protocol that moves bid requests and responses during an impression. PPC Land's OpenRTB explainer covers it. OpenDirect operates days or weeks earlier and reuses OpenRTB's PMP and Source objects only to describe products.

The Deals API, which IAB Tech Lab released for public comment on December 5, 2025, pushes the metadata of an already agreed deal from a supply-side platform to a demand-side platform. It does not search catalogues or book inventory, and version 1.0 excludes negotiation.

OpenProposal, the draft core of AAMP 3.0, describes how agents exchange and compare proposals. Each agreed line then executes through OpenDirect 2.1, the Deals API or OpenRTB 2.6.

Recent developments

IAB Tech Lab announced in September that it was moving its specifications from PDFs to Markdown on GitHub, the format in which OpenDirect 2.1 already lives. AAMP 3.0, released on September 22, places OpenDirect at the execution end of agentic buying through OpenProposal's transaction_mechanism field. On October 23, IAB Tech Lab extended comments on AAMP 3.0 to November 10, adding 19 days to the window. No new OpenDirect version has been announced.

Timeline

  • June 2013: AOL, Yahoo, Microsoft and Yieldex form a working group to standardise automated sales of reserved inventory
  • September 19, 2014: Mediaocean's Vedant Sampath publishes analysis of lagging automated guaranteed adoption in AdExchanger
  • November 3, 2014: IAB releases OpenDirect 1.0 for public comment, open until December 3
  • January 2015: OpenDirect 1.0 finalised
  • January 12, 2016: Google opens Programmatic Guaranteed in public beta, using deal IDs rather than OpenDirect
  • March 2016: OpenDirect 1.5 released, adding multi-currency support and change requests
  • January 2018: OpenDirect 2.0 released for public comment until March 12, adopting AdCOM and buyer-seller messaging
  • February 13, 2019: Final OpenDirect 2.0 date, according to Kochava's XCHNG announcement
  • May 2021: OAAA releases OpenDirect 1.5.1 for out-of-home media
  • July 8, 2024: OpenDirect 2.1 committed and reverted on GitHub
  • September 19, 2024: OpenDirect 2.1 restored; outdoor trade bodies announce it later that month
  • December 5, 2025: IAB Tech Lab releases the Deals API 1.0 for public comment
  • January 6, 2026: IAB Tech Lab's agentic roadmap commits to extending OpenDirect
  • March 2026: Kochava opens an AAMP workspace built on OpenDirect 2.1 to public beta
  • September 22, 2026: AAMP 3.0 and OpenProposal released, mapping execution to OpenDirect 2.1
  • October 23, 2026: AAMP 3.0 comment period extended to November 10

Summary

Who: IAB Tech Lab maintains OpenDirect through its OpenDirect Working Group. AOL, Yahoo, Microsoft and Yieldex started it, Bionic Advertising Systems and MediaMath joined, and out-of-home bodies OAAA, OMA and Outsmart led the 2.1 work. Publishers and media owners expose the API; buying platforms and, increasingly, AI buyer agents call it.

What: A RESTful API specification for automated guaranteed buying, covering product search, availability and pricing, orders and lines, creative assignment, reservation, booking, change requests and reporting.

When: Formed as a working group in June 2013, released for comment in November 2014 and finalised in January 2015, revised in 2016, 2018-2019 and 2024. Version 2.1 is current as of October 2026.

Where: Between a buyer's planning or buying platform and a publisher's order management system and ad server, before delivery and outside the real-time auction.

Why: To replace RFPs, insertion orders and manual trafficking for reserved inventory with one standard integration, and, since 2026, to give AI agents a defined path to book guaranteed media.