Two ways to find an ad
Unsponsored is a Chrome extension that skips the sponsor reads in YouTube videos. It asks SponsorBlock's crowd-sourced list first. When the crowd has nothing for a video, a model of your choosing reads the transcript and points at the ad.
You bring the key. Eleven presets cover OpenAI, Grok, Claude, Gemini, Groq, Mistral, DeepSeek, OpenRouter, Ollama and LM Studio, plus any OpenAI-compatible endpoint, and all of them collapse into four request shapes.
Asking without telling
The video ID never goes to SponsorBlock. The extension hashes it with SHA-256 and sends the first four hex characters. SponsorBlock answers with every labelled video in that bucket and the match is picked locally, so all it learns is that you are watching one of them.
With a local model through Ollama or LM Studio, the transcript never leaves your computer. There is no server of mine anywhere in the path, no account and no analytics.
The model points, plain code decides
Captions are grouped into numbered lines of about five seconds, and the model answers with line numbers and a short quote, never timestamps. Models point at a line far better than they do arithmetic, and a line number can be checked: it exists or it does not.
Every answer then goes through plain code. The lines must exist in the chunk the model was shown, the quote must really be in them, a skip must last between 3 seconds and 10 minutes, and everything found together can cover at most 40% of a video. A transcript is text anyone can put in a video, so that check is also the prompt injection defence. One of the tests is called “a model told to skip everything cannot”.
Measured, not claimed
It ships with a small study anyone can re-run: 60 videos drawn at random by hash prefix, 40 with a sponsor read and 20 without. Grok 4.3 found the read in 36 of the 40, every segment it skipped as a sponsor really was one, and it skipped nothing in the 20 videos without an ad. The whole study cost $0.44. A small local model, qwen2.5 7B, found 30 of 40, for free, on a Mac.
One finding changed the design. Hand-written captions sometimes leave the ad out entirely, so the extension reads YouTube's automatic captions first.
YouTube's own ads
Version 0.2.0 also ends YouTube's ads, but only once YouTube itself offers the Skip button. YouTube ignores clicks made by scripts, so the ad clip is moved to a tenth of a second before its end instead, and only when the clip's length matches the player's ad clock, so it can never skip the real video. Ads without a Skip button play normally. Nothing is blocked.