What aI browsers and extensions tools are for
AI browsers and extensions bring an assistant into the place where you read and work online. Depending on the tool, you can summarise a page, ask questions about a document or compare information across open tabs. They can help researchers, office workers, students and anyone who regularly moves between websites and notes. The practical change is less copying between your browser and a separate chat window, while checking the answer remains your responsibility. For example, preparing a comparison might normally mean collecting terms from several service pages into a document. With a suitable assistant, you can request a comparison of those tabs and then check each point against the original wording. Comet and Dia support working across tabs. Sider can summarise pages and YouTube videos. The useful starting point is your actual browsing routine and the content the assistant can access.
Example uses:
- You summarise an open page to identify the sections that deserve a closer reading.
- You compare information across browser tabs while preparing a research note for later verification.
- You ask questions about a document to locate details relevant to your current task.
- You draft an email in the browser and revise its wording before sending it.
- You summarise a supported video to decide which passages you need to watch carefully.
The main tools at a glance
Comet 55/100
Comet is a browser that summarizes pages and compares information across tabs. It serves people who want to write emails or fill out forms with an assistant while browsing. Features: Summarize the page being viewed; Compare information across multiple tabs; Write emails from the browser. Entry price: $20 per month, with a free tier. Runs on: Windows, macOS, iPhone and iPad, and Android.
Sider 55/100
Sider lets browser users access multiple models in a sidebar, summarize pages and YouTube videos, and ask questions about documents. It also translates content, automates browser actions, and generates images and presentations. Features: Use multiple models in a sidebar; Summarize pages and YouTube videos; Ask questions about documents. Free tier available. Runs on: web browser, Windows, macOS, iPhone and iPad, Android, and browser extension. Data hosting: Several regions.
Monica 55/100
Monica lets users chat with multiple AI models, summarize pages and videos, and ask questions about PDFs. It also translates documents while preserving layout and generates images and videos. Features: Chat with multiple AI models; Summarize pages and videos; Ask questions about PDF documents. Entry price: $99 per year, with a free tier. Runs on: web browser, Windows, macOS, iPhone and iPad, Android, browser extension, and API. Data hosting: United States.
Merlin 48/100
Merlin helps people query several models through one interface. It summarizes pages and videos, analyzes documents, drafts replies and posts, and searches for information on the web. Features: Query several models from one interface; Summarize pages and videos; Analyze documents. Entry price: $19 per month, with a free tier. Runs on: web browser, browser extension, iPhone and iPad, Android, and macOS. Data hosting: United States.
Dia 40/100
Dia is a macOS browser for people who want to ask questions about pages, multiple tabs and connected applications. It also supports preparing documents and organizing tabs and browsing profiles. Features: Ask questions about a page being viewed; Cross-reference information from multiple tabs; Query connected applications. Entry price: $20 per month, with a free tier. Runs on: macOS.
Opera Neon 40/100
Opera Neon lets users ask questions about open pages, perform actions on websites, and research with multiple agents. It also creates websites and tools from requests and groups tabs by task. Features: Ask questions about open pages; Perform actions on visited websites; Conduct research with multiple agents. Entry price: $19.9 per month, with a free tier. Runs on: Windows and macOS.
The category in figures
Of the 6 tools in the category, 6 (100%) offer a free tier, 17% have a public API and 1 have a French interface. The median entry price, per month, is $19.9 (across 5 tools with a published price). 3 disclose where data is hosted, 0 of them in Europe or on device.
All aI browsers and extensions tools
Click a header to sort. Data checked on official sites, October 24, 2026.
| Tool | Free | Entry price | API | Data | Score |
|---|---|---|---|---|---|
| Comet Comet is a browser that summarizes pages and compares information across tabs. It serves people who want to write emails or fill out forms with an ass | Yes | $20 per month | – | Not disclosed | 55 |
| Sider Sider lets browser users access multiple models in a sidebar, summarize pages and YouTube videos, and ask questions about documents. It also translate | Yes | not published | – | Several regions | 55 |
| Monica Monica lets users chat with multiple AI models, summarize pages and videos, and ask questions about PDFs. It also translates documents while preservin | Yes | $99 per year | Yes | United States | 55 |
| Merlin Merlin helps people query several models through one interface. It summarizes pages and videos, analyzes documents, drafts replies and posts, and sear | Yes | $19 per month | No | United States | 48 |
| Dia Dia is a macOS browser for people who want to ask questions about pages, multiple tabs and connected applications. It also supports preparing document | Yes | $20 per month | – | Not disclosed | 40 |
| Opera Neon Opera Neon lets users ask questions about open pages, perform actions on websites, and research with multiple agents. It also creates websites and too | Yes | $19.9 per month | – | Not disclosed | 40 |
Also useful
These tools belong to another category but also cover this need:
- LanguageTool LanguageTool helps people writing texts correct spelling, grammar, and punctuation errors. It also lets users
- Bardeen Bardeen helps people build prospect lists using information from web pages. It extracts information, enriches
- Jetwriter AI Jetwriter AI serves users writing emails and reading web pages. It drafts replies adapted to their style, corr
- Brisk Teaching Brisk Teaching helps teachers prepare lessons, quizzes and teacher-guided activities. It also supports adjusti
Choosing well and avoiding pitfalls
Test each option on pages you actually visit, including long articles, tables and French content if you need it. Check whether the assistant can access the full page, attached documents and relevant tabs. Useful answers should make their supporting passages easy to find. Review permissions, site access controls and data retention terms before connecting work accounts. Also consider browser compatibility, copying or exporting results, and connections to your existing applications. Compare usage limits and billing rules for the available models. A convenient interface matters less if it cannot reliably read the material your work depends on.
A summary can drop an exception, mix up tabs or treat an old page as current. Check consequential details in the original context. Browser access can also expose personal information and confidential work content. Restrict permissions and avoid sensitive pages when the service’s protections are unclear. If an assistant can perform actions, inspect the destination and completed fields before confirmation. Text embedded in a website may contain misleading instructions, so keep your task explicit and review unexpected behaviour.
To compare with the cost of using an AI model directly, see the API price calculator.
Free or paid?
Free plans generally let you explore the interface, ask questions and try page summaries. Restrictions may apply to model access, document length or how often you can make requests. Paying can make sense when those limits regularly interrupt useful work or when additional controls are needed. Check the terms for your specific workflow before choosing a subscription.
Tools in the category with a free tier: Comet, Sider, Monica, Merlin, Dia, and Opera Neon.
For which jobs?
The profiles that use these tools most, based on the use cases documented by publishers: content writers, students, marketers, researchers, freelancers, and project managers.
Related categories
Learn more
Frequently asked questions
What is the best tool to use AI right in your browser?
On our access and transparency grid, Comet (55/100), Sider (55/100), and Monica (55/100) come first. Test two of them on your own examples: output quality depends a lot on your case.
Are there free tools?
Yes, 6 of 6 tools have a free tier, often limited in volume: Comet, Sider, Monica, and Merlin.
Can the assistant automatically read every open tab?
Access depends on the browser, extension and permissions you grant. Some assistants work with the active page, while others use selected tabs. Check the settings and ask which material supports an answer. Do not assume that an open page, especially one behind a login, has been read completely.
Is it suitable for confidential work documents?
Check your organisation’s rules and the service’s data terms before using it. Look at what leaves the browser, how it is retained and whether you can delete it. Limit site access where possible. If the answers remain unclear, use anonymised examples or an environment approved for confidential material.
Can I rely on a summary when comparing services?
Use it as a draft comparison that you can inspect. A summary may omit restrictions or combine terms that apply to different situations. Request the supporting passages and revisit the original pages. Check dates, eligibility and relevant exclusions before making a decision based on the comparison.
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Neutrality. No affiliate links. No vendor pays to be reviewed, rated or ranked. Reviews are directed by François Chollet, neutral and factual, and every data point is dated and sourced. How we score