Glasp and YouTube Spoiler are both Chrome extensions that can summarize YouTube videos, but they are aimed at different users with different goals. Glasp is a research and note-taking platform. YouTube Spoiler is a feed-triage tool. Understanding that distinction will save you from installing the wrong one.
What Glasp Actually Is
Glasp started as a web highlighting tool — you select text on any web page and Glasp saves it to your profile. The YouTube summarization feature was added on top of that core. When you open a YouTube video, Glasp shows a sidebar with a transcript and an AI-generated summary. It also has a social layer: you can follow other users, see their highlights, and share your own.
The social angle is Glasp's genuine differentiator. If you are a researcher who wants to share annotated reading lists with collaborators, or a student comparing notes with classmates, that community dimension adds real value. For someone who just wants to know whether a video is worth watching before clicking on it, the same features add friction.
What YouTube Spoiler Actually Is
YouTube Spoiler is narrowly focused on one thing: letting you hover over a YouTube thumbnail and get an AI summary without opening the video. It works on the homepage, search results, recommended feed, and channel pages. The entire workflow is hover, click Spoil, read bullet points, decide. No video, no watch page, no new tab.
It supports 35 languages, does not require an account, and starts working immediately after installation.
Feature Comparison
| Feature | YouTube Spoiler | Glasp |
|---|---|---|
| Summarize from thumbnail | Yes | No |
| Works on YouTube feed / homepage | Yes | No |
| AI bullet-point summaries | Yes | Yes |
| Full transcript view | No | Yes |
| Web page highlighting | No | Yes |
| Social / sharing features | No | Yes |
| Account required | No | Yes |
| Language support | 35 languages | English-first |
| Free tier | 3/day, no account | Limited credits/mo |
| Paid plan | $3.99/mo unlimited | from ~$9/mo |
Pricing
YouTube Spoiler: 3 free summaries per day (no account required), Pro unlimited at $3.99/mo.
Glasp: a free plan with a limited number of AI summary credits per month; additional usage via paid plans (pricing has varied — check Glasp's website for current rates). An account is required even for the free tier.
When to Use YouTube Spoiler
- You want to triage your YouTube feed in seconds without opening videos
- You do not want to create an account or sign in to anything
- You need summaries in languages other than English
- You want unlimited summaries at the lowest possible price
- You just want one thing: "what is this video about?"
When to Use Glasp
- You are doing research and want to highlight and annotate web pages alongside videos
- You want a transcript of the full video alongside an AI summary
- You want to share your reading/viewing notes with others
- You are building a knowledge base from multiple content types (articles + videos)
- The social and community layer is valuable to your workflow
The Honest Take
Glasp is a more powerful tool for knowledge workers who need to annotate, highlight, and share content across the web. If that is you, its YouTube summarization feature is a good bonus on top of something you would use anyway.
If you primarily want to know whether a YouTube video is worth watching before you open it, Glasp is heavier than you need. YouTube Spoiler answers that specific question faster, cheaper, and with no account friction.
Frequently Asked Questions
What is Glasp and how does it differ from YouTube Spoiler?
Glasp is a social web-highlighting and annotation tool that includes YouTube video summarization as one of its features. It requires opening a video on the watch page before you can generate a summary. YouTube Spoiler is focused purely on fast summaries from thumbnails — you never need to open the video. Glasp is better for research and note-taking; YouTube Spoiler is better for fast feed triage.
Is Glasp free?
Glasp has a free plan with limited AI summary credits per month. Additional usage requires a paid plan. YouTube Spoiler gives 3 free summaries per day with no account required, and Pro unlimited is $3.99/mo.
Does Glasp work on the YouTube homepage?
No. Glasp only activates on the video watch page (youtube.com/watch). YouTube Spoiler works across the YouTube homepage, search results, recommended feeds, and channel pages — anywhere thumbnails appear.
Can Glasp summarize YouTube videos without an account?
No, Glasp requires creating an account. YouTube Spoiler requires no account or login and starts working immediately after installation.
Related: YouTube Spoiler vs Eightify • YouTube Spoiler vs NoteGPT • Best YouTube Summarizer Extensions