What is a Demand-Side Platform (DSP)?
A demand-side platform (DSP) is software that lets advertisers buy ad inventory programmatically — bidding on ad space across multiple publishers and exchanges through a single interface.
Instead of negotiating with each publisher individually, a DSP lets you set your targeting criteria, budget, and bid strategy, and it buys impressions automatically via real-time auctions.
How DSPs Work
Every time someone loads a web page with ad space, an auction happens in milliseconds:
- The publisher's supply-side platform (SSP) sends the available impression to ad exchanges
- Your DSP evaluates the impression — does this user match your targeting? Is it worth bidding on?
- The DSP places a bid based on your settings
- The highest bidder wins, and their ad is displayed
This entire process — called real-time bidding (RTB) — happens in under 100 milliseconds, before the page finishes loading.
DSP vs. Self-Serve Platforms
Google Ads and Meta Ads are technically DSPs for their own inventory. But when people say "DSP," they usually mean platforms that buy across the open web — sites, apps, connected TV, and digital out-of-home.
Self-serve platforms (Google, Meta, TikTok): simpler, limited to that platform's inventory, lower minimums.
Independent DSPs (The Trade Desk, DV360, Amazon DSP): more control, cross-platform reach, better for audience-first buying and programmatic campaigns. Usually require higher budgets and more expertise.
When DSPs Make Sense
For most advertisers running campaigns on Google and Meta, a DSP is overkill. They become useful when:
- You need to reach audiences across thousands of publishers from one place
- You want to buy connected TV (CTV) or digital out-of-home inventory
- You have first-party data and want to match it against ad exchanges for precise targeting
- Your CPM on walled gardens is too high and you want open-web alternatives
Frequently Asked Questions
An ad network bundles inventory from publishers and sells it as packages. A DSP gives you direct access to multiple ad exchanges and lets you bid on individual impressions in real-time. DSPs offer more control, granular targeting, and transparency into where your ads appear. Ad networks are simpler but less flexible.
Major DSPs include Google DV360 (Display & Video 360), The Trade Desk, Amazon DSP, MediaMath, and Xandr (Microsoft). Google Ads and Meta Ads also function as DSPs for their own inventory, though they're usually categorized as self-serve ad platforms.
Most small to mid-size advertisers don't. Google Ads and Meta Ads cover the majority of digital ad inventory. DSPs become valuable when you need to buy across many publishers, want advanced audience targeting with first-party data, or need programmatic access to premium inventory like connected TV or digital out-of-home.