Programmatic · also called DSP, demand-side platform
DSP (demand-side platform)
A DSP (demand-side platform) is software that advertisers and agencies use to buy ad impressions automatically across many exchanges and publishers, deciding which impressions to bid on and how much.
A demand-side platform is the buyer's control panel for programmatic advertising. Advertisers or their trading desks load campaigns, budgets, targeting, frequency capping, deals and brand safety rules into it. The DSP then listens to billions of bid requests a day from SSPs and exchanges, evaluates each one, and bids on those that match.
Under the hood a DSP combines a bidder (fast servers that price each impression), data integrations (audiences, identity, contextual signals), pre-bid filters for invalid traffic and brand safety, and reporting. Independent DSPs include The Trade Desk; others belong to larger platforms, such as Google's Display & Video 360 and Amazon DSP. Microsoft wound down its Xandr-based DSP (Microsoft Invest) in 2026.
DSPs usually charge a percentage of media spend as their fee, part of the ad tech tax. Buyers compare DSPs on inventory access, data, supply path optimization, transparency of fees and log-level data, and how well they avoid fraud.
Think of it like this
A DSP is like a personal shopper with a strict brief who visits every market stall at once and buys only the items that match your list and budget.
An example
An agency sets up a DSP line item: bid up to US$6 CPM for viewable video on 3,000 approved news sites in Europe, cap 3 per user per day, budget €40,000.
Related terms
SSP (supply-side platform)
An SSP (supply-side platform) is software that publishers use to sell their ad inventory automatically to many buyers, running auctions and managing prices, deals and quality controls.
Real-time bidding (RTB)
Real-time bidding (RTB) is an automated auction in which advertisers bid on a single ad impression in the fraction of a second while a web page, app or stream is loading.
Trading desk
A trading desk is a specialist team, usually inside an agency or advertiser, that plans and executes programmatic buying on DSPs on behalf of campaigns and clients.
Supply path optimization (SPO)
Supply path optimization (SPO) is a buyer's practice of choosing the most direct, cheapest and most trustworthy routes to the same inventory, and cutting unnecessary resellers and duplicate paths.
Win rate
Win rate is the percentage of bids a buyer submits that actually win the auction, calculated as auctions won divided by bids placed, multiplied by 100.