--- title: "What Is CSAI? Client-Side Ad Insertion Explained | RentAnOTT" description: "CSAI inserts video ads in the player on the viewer's device. See how it works, its strengths in measurement and interactivity, and where SSAI does better." url: "https://www.rentanott.com/glossary/csai" markdown_url: "https://www.rentanott.com/glossary/csai.md" category: "Advertising" updated: "2026-10-05" --- # What is CSAI? CSAI (client-side ad insertion) is a way of delivering video advertising in which the player on the viewer's device requests each ad from an ad server and plays it itself, pausing the program while the ad runs. ## How CSAI works The player contains an ad SDK. At an ad break, the SDK calls the ad server, receives a response describing the ad, loads the ad's video file and plays it, usually in a second player layered over the first. It fires tracking signals as the ad starts, reaches each quarter and finishes, then hands back to the program. ## Strengths - Measurement: the device reports directly, which advertisers and verification vendors trust - Interactivity: clickable, skippable and overlay ads are straightforward - Targeting: device signals are available to the ad request - Simplicity: no stitching infrastructure is needed - Wide support among ad networks ## Weaknesses - Ad blockers can stop the ad request on the web - The switch between program and ad can show a pause or a spinner - Ad quality may not match the program's, since the ad is a separate file - Every device platform needs its own SDK integration - Hard to time precisely in live streams ## CSAI vs SSAI SSAI stitches ads into the stream on the server, giving seamless playback and resistance to ad blocking at the cost of harder measurement. CSAI is common for on-demand video on the web and mobile; SSAI for live, linear channels and television. Some services use both, or a hybrid in which the server guides the player. ## CSAI on RentAnOTT AVOD is included on every RentAnOTT plan, with advanced advertising as a $169/month add-on. For the server-side alternative, see the SSAI entry. [Read about SSAI](https://www.rentanott.com/glossary/ssai). ## Related terms - [SSAI](https://www.rentanott.com/glossary/ssai) — SSAI (server-side ad insertion) is a way of delivering video advertising in which the ads are stitched into the stream on the server before it reaches the viewer. The player receives one continuous stream containing both program and ads. - [Dynamic ad insertion](https://www.rentanott.com/glossary/dynamic-ad-insertion) — Dynamic ad insertion (DAI) is choosing which ads to show at the moment a viewer reaches an ad break, individually for that viewer, instead of permanently embedding the same ads in the video file for everyone. - [VAST](https://www.rentanott.com/glossary/vast) — VAST (Video Ad Serving Template) is the industry standard, published by the IAB Tech Lab, for how an ad server describes a video ad to a player. A VAST response is an XML document that tells the player which media file to play and which tracking addresses to call. - [Ad server](https://www.rentanott.com/glossary/ad-server) — An ad server is the system that decides which ad to show each time a player or stitching service asks for one, delivers the details of that ad and counts the result. For a publisher it is the control center of an advertising business. - [Pre-roll ad](https://www.rentanott.com/glossary/pre-roll) — A pre-roll ad is a video advertisement that plays before the content a viewer chose. It is the simplest ad position to implement, since it needs no markers inside the video. - [Mid-roll ad](https://www.rentanott.com/glossary/mid-roll) — A mid-roll ad is a video advertisement that plays in a break partway through the content, in the manner of a television commercial break. It is the main ad position for long-form and live video. - [Video player](https://www.rentanott.com/glossary/video-player) — A video player is the software on a viewer's device that requests a stream, decodes it and displays it, and provides the controls for watching. In a streaming service it also handles adaptive quality, DRM, subtitles, advertising and analytics. ## Further reading - [Pricing](https://www.rentanott.com/pricing) - [Content monetization platforms compared](https://www.rentanott.com/blogs/content-monetization-platforms) - [OTT revenue calculator](https://www.rentanott.com/tools/ott-revenue-calculator) ## Frequently asked questions ### What does CSAI stand for? CSAI stands for client-side ad insertion. ### Is CSAI being replaced by SSAI? Not replaced. SSAI has taken over live and television, while CSAI remains widespread for on-demand video on web and mobile, where interactivity and direct measurement matter. ### Does CSAI support skippable ads? Yes. Because the player controls the ad, it can show a skip button and report when it is used. All 163 terms: [Streaming and OTT glossary](https://www.rentanott.com/glossary). ## Book a demo Tell RentAnOTT what you are launching. The team walks through the platform and maps the path to go-live around your catalog, markets and revenue model. Book a demo: https://www.rentanott.com/contact ## More from RentAnOTT - [Home](https://www.rentanott.com/index.md) — What RentAnOTT is, what every plan includes, and how launch works - [Features](https://www.rentanott.com/features.md) — Every core feature and optional add-on - [Pricing](https://www.rentanott.com/pricing.md) — Platform tiers, apps, add-ons, usage rates and example bills in INR and USD - [Free tools](https://www.rentanott.com/tools.md) — OTT app builder and calculators for streaming revenue, bandwidth, bitrate and pricing - [Insights](https://www.rentanott.com/blogs.md) — All streaming business articles - [Glossary](https://www.rentanott.com/glossary.md) — Definitions of streaming and OTT terms - [Book a demo](https://www.rentanott.com/contact.md) — Talk to RentAnOTT about your launch Full site in one file: https://www.rentanott.com/llms-full.txt