# Server-Side Ad Insertion
> Technology profile in The State of Streaming directory.
- Profile type: Technology
- Profile status: baseline
- Last updated: 2026-05-03T00:00:00.000Z
- Canonical URL: https://thestateofstreaming.com/tech/ssai-server-side-ad-insertion/
- Also known as: SSAI, ad stitching, dynamic ad insertion
## Summary
Server-side ad insertion (SSAI) is the streaming-video plumbing that splices ads into the same video manifest as the content, server-side, before bytes reach the device. It is the foundational primitive that makes CTV, AVOD, and FAST monetization possible at broadcast quality.
## Definition
Server-side ad insertion is a video delivery technique in which ad creatives are stitched into the content manifest on the server — the HLS or DASH playlist the player downloads — so that ads and program material arrive at the device as a single, continuous stream over the same TCP/HTTPS connection. Because the player does not make a separate ad call, SSAI defeats client-side ad blockers, eliminates the buffering and player-state errors that plague client-side insertion (CSAI), and renders ads at the same bitrate, codec, and frame rate as the content. SSAI is the foundational primitive of CTV, AVOD, and FAST monetization: every ad-supported streaming service of consequence either runs an SSAI vendor or operates its own stitcher. A typical SSAI workflow combines an origin or live encoder, an ad decision service that resolves a VAST response per impression, a manifest manipulator that splices the ad segments into the playlist, and a tracking layer that fires VAST beacons server-side using IAB Tech Lab macros so measurement and verification still work without a client-side SDK. The sister term DAI (dynamic ad insertion) is used interchangeably by some vendors — Google in particular — and refers to the same server-stitched delivery model; SSAI is the IAB-preferred technical term and DAI is the more common commercial label.
## Market size
U.S. CTV ad spend forecast to grow 13.8% in 2026 — SSAI is the delivery primitive underneath effectively all of it (as of 2026-01-29). Source: IAB 2026 Outlook Study — https://www.streamtvinsider.com/advertising/iab-forecasts-138-us-ctv-ad-spend-growth-2026

## Key trends

- Server-guided ad insertion (SGAI), built on HLS Interstitials and MPEG-DASH Events, is emerging as the next-generation hybrid — the server identifies the slot but the client fetches and plays the ad — reducing origin load on long-tail VOD and extended DVR while preserving SSAI's ad-blocker resistance.
- Live-event scale is the proving ground: Google Ad Manager DAI delivered 7 million concurrent 1:1 addressable streams during the PSG vs Real Madrid FIFA Club World Cup match in 2025, resetting the bar for what SSAI infrastructure must handle.
- Low-latency live SSAI is closing the gap with broadcast — AWS launched Amazon IVS Low-Latency Streaming SSAI via MediaTailor in April 2026, and Yospace, FreeWheel, and Wowza all now ship low-latency HLS/DASH stitchers.
- VAST 4.x and the IAB Tech Lab SSAI/VAST Macros spec (v1.0, November 2020) have hardened server-side measurement, verification, and macro-driven targeting — making SSAI streams interoperable with the same OMID/MOAT/DV/IAS verification pipeline as CSAI.
- Pod-serving architectures (Google's DAI Pod Serving, FreeWheel's pod logic, custom publisher stitchers) are decoupling ad decisioning from manifest manipulation, letting publishers keep their own CDN and origin while outsourcing only the auction and pod construction.


## Major players

- alphabet — https://thestateofstreaming.com/companies/alphabet/
- amazon — https://thestateofstreaming.com/companies/amazon/
- comcast corporation — https://thestateofstreaming.com/companies/comcast-corporation/
- brightcove — https://thestateofstreaming.com/companies/brightcove/
- yospace — https://thestateofstreaming.com/companies/yospace/
- akamai — https://thestateofstreaming.com/companies/akamai/
- wowza — https://thestateofstreaming.com/companies/wowza/


## Key facts

- IAB Tech Lab published the SSAI VAST Macros v1.0 specification in November 2020, standardizing how SSAI servers pass context (device, IP, content, session) into VAST ad calls. — IAB Tech Lab: https://iabtechlab.com/wp-content/uploads/2020/11/IABTechLab_SSAI_VAST_Macros_v1.0-Nov-2020.pdf
- VAST 4.1, released in 2018, was the first VAST version to address SSAI explicitly via macros for server-to-server communication; VAST 4.3 tightened HTTP-header requirements for SSAI. — IAB: https://www.iab.com/news/vast-4-1/
- Google Ad Manager Dynamic Ad Insertion served 7 million concurrent 1:1 addressable streams during the PSG vs Real Madrid FIFA Club World Cup match. — Google Ad Manager: https://admanager.google.com/home/resources/feature-brief-dynamic-ad-insertion/
- Amazon IVS Low-Latency Streaming added SSAI support via AWS Elemental MediaTailor in April 2026, extending server-stitched ads to sub-three-second live latency. — AWS: https://aws.amazon.com/about-aws/whats-new/2026/04/amazon-ivs-low-latency-streaming-server-side-ad-insertion/
- The IAB 2026 Outlook Study forecasts U.S. CTV ad spend will grow 13.8% in 2026, second only to social at 14.6% among ad channels. — IAB / StreamTV Insider: https://www.streamtvinsider.com/advertising/iab-forecasts-138-us-ctv-ad-spend-growth-2026


## External coverage

- 2020-11-30 — IAB Tech Lab: SSAI Digital Video Ad Serving — VAST Macros v1.0 (https://iabtechlab.com/wp-content/uploads/2020/11/IABTechLab_SSAI_VAST_Macros_v1.0-Nov-2020.pdf)
- Amazon Web Services: AWS Elemental MediaTailor Documentation (https://docs.aws.amazon.com/mediatailor/)
- Google: Evolving Dynamic Ad Insertion for the future of streaming (https://blog.google/products/admanager/evolving-dai-future-streaming/)
- AdExchanger: AdExplainer: What Is Server-Side Ad Insertion (SSAI)? (https://www.adexchanger.com/adexplainer/adexplainer-what-is-server-side-ad-insertion-ssai/)

## Profile
Server-side ad insertion is the unglamorous plumbing that makes the rest of CTV ad-tech matter. Every addressable buy, every programmatic-guaranteed deal, every FAST channel pod, every shoppable-ad demo eventually has to hit a player on a Roku, a Fire TV, a Vizio, or a smart-TV-bundled Samsung TV Plus tile — and almost all of them get there through a server-stitched manifest. Without SSAI, CTV would have inherited the worst of pre-roll web video: ad blockers stripping inventory, clients dropping the SDK call, mid-roll buffering wheels, codec mismatches between content and ad. With it, the viewer cannot tell the ad break from the show, which is the entire commercial proposition.

The market shape is straightforward and stable. The two hyperscaler-backed services — **Google Ad Manager DAI** and **AWS Elemental MediaTailor** — anchor the high end and run the largest live events on the planet, with Google's 7-million-concurrent FIFA Club World Cup stream serving as the current high-water mark for what an SSAI infrastructure must absorb. Beneath them, **FreeWheel** (a Comcast company) is the incumbent for premium broadcasters and MVPDs in North America, **Yospace** (RTL Group) is the live-broadcast specialist of choice in Europe and increasingly the loudest voice on the next-generation server-guided model, and **Brightcove**, **Wowza**, and **Akamai** sell SSAI as part of broader video-platform or CDN bundles. **Amagi** and **Wurl** package SSAI inside the cloud-playout and FAST-distribution layers their channel-launcher customers actually buy. The category is mature enough that vendor consolidation runs through bundling and partnership rather than greenfield entrants.

A note on terminology that matters more than it should: **DAI** (dynamic ad insertion) and **SSAI** are used interchangeably across the vendor landscape — Google is the loudest holdout for the DAI label — but they describe the same server-stitched delivery model. The IAB-preferred technical term is SSAI; DAI is the older commercial brand. **SGAI** (server-guided ad insertion) is the genuinely new thing — a hybrid built on HLS Interstitials and MPEG-DASH Events in which the server identifies ad slots and signals the client to fetch and play, splitting the load between origin and device. SGAI is not a replacement for SSAI; it is an additional mode that the same vendors are shipping for cases where origin compute or extended-DVR economics make pure server-stitching unattractive. Treat the three terms as a spectrum of where the ad-pod work happens, not as competing categories.

What is worth watching from here is less the underlying stitching technology — that is solved — and more what publishers and platforms layer on top of it: pod-serving APIs that decouple decisioning from manifest manipulation, server-side OMID/verification reaching parity with client-side measurement, low-latency live SSAI that no longer trades latency for monetization, and the slow but inexorable pull of shoppable, interactive, and creator-personalized ad formats into the server-stitched stream where they can actually scale.

## Tags

- SSAI
- DAI
- SGAI
- CTV-ads
- video-monetization
- ad-tech
- streaming-infrastructure
- VAST
- FAST
- AVOD

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