What Is Fellou Browser?
Fellou is a browser that automates web-based tasks using AI. Unlike traditional browsers, it not only displays websites but can also take actions on your behalf, such as performing research, comparing competitor data, compiling reports, and interacting with websites that require login credentials.
Fellou uses a model that plans tasks before acting. It first generates a step-by-step action plan based on your prompt, then executes it automatically. This approach allows users to review and modify the plan beforehand, giving them control over what the AI does.
Fellou can operate across multiple platforms and web apps simultaneously, turning natural language commands into coordinated actions. It’s also capable of system-level tasks, such as managing desktop files and controlling local applications.
This is part of a series of articles about AI browser
In this article:
- Fellou Browser Key Features
- Fellou Browser Pricing
- Fellou Browser Review: The Pros and Cons
- Fellou Browser Security Concerns
Fellou Browser Key Features
Fellou combines AI-driven planning, agentic memory, and full-stack automation to carry out complex tasks across websites, platforms, and even your desktop. Below are the core features that show how it actually works in practice:
- Natural language to workflow automation: You can describe a goal, such as researching competitor pricing, compiling market insights, or drafting reports, and Fellou turns it into a detailed, step-by-step action plan. It breaks the task into discrete actions across platforms like Google, Reddit, Notion, and X, then runs them automatically without manual clicks.
- Cross-app, multi-platform execution: Fellou isn’t limited to a single tool. It can work across multiple services in parallel, such as querying Google for product comparisons, scanning Reddit for market sentiment, and collecting structured data into a Notion page. These tasks can run concurrently in the background, allowing users to continue browsing or step away entirely.
- Real-time plan review and intervention: Before executing a workflow, Fellou shows you the full plan, allowing for edits and approvals. During execution, you can pause and make corrections on the fly. This makes it possible to fix errors or reroute actions without restarting the process.
- End-to-end web automation: Fellou can automate entire workflows across the web: scraping data, submitting forms, downloading content, and navigating multi-step processes. It handles these actions in sequence, making it capable of performing start-to-finish tasks based on a single prompt.
- Logged-in access and deep search: Fellou operates with access to logged-in platforms (like Reddit or Notion), which enables it to perform personalized research and generate reports that include data behind authentication gates. It can create traceable outputs with source links, making it useful for verifiable research.
- System-level control: Beyond the browser, Fellou integrates with your desktop. When granted permission, it can control local applications, manage files, and carry out tasks like saving research outputs or opening specific tools, blurring the line between browser and full operating assistant.
- Agentic memory and context awareness: Fellou learns from your browsing activity, history, and notes to understand your workflow and context. It can recall past tasks and use that context in new instructions, reducing repetition and making interactions more efficient.
- Dynamic multitasking: Fellou’s backend can juggle multiple tasks simultaneously. For example, it can monitor news updates on Oracle and NVIDIA while compiling a Notion report and scheduling a calendar reminder, enabling real-time productivity across domains.
Fellou Browser Pricing
Fellou offers four pricing tiers:
Free:
- 1000 Sparks (one-time bonus for new users), roughly enough for 4 tasks
- 2 scheduled tasks
- Unlimited concurrent tasks (limited-time access)
Plus: $19.9/month
- 2000 Sparks/month (approx. 8 tasks)
- 3 scheduled tasks
- Unlimited concurrent tasks (limited-time access)
- Priority support
- Early access to new features
Pro: $39.9/month
- 5000 Sparks/month (approx. 20 tasks)
- 5 scheduled tasks
- Unlimited concurrent tasks (limited-time access)
- Priority support
- Early access to new features
Ultra: $199.9/month
- Unlimited Sparks (for a limited time)
- Unlimited scheduled and concurrent tasks
- Exclusive priority support
- Early access to new features
Each paid tier increases the number of Sparks (the unit of task execution), scheduled tasks, and support level. Ultra removes all caps and is suited for users with high-volume or mission-critical automation needs.
Fellou Browser Review: The Pros and Cons
Fellou stands out for its architecture and automation capabilities, but it also comes with limitations that affect reliability. Here’s a breakdown of the main pros and cons.
Pros
- Agentic task execution: Fellou can interpret plain-language prompts and carry out multi-step actions across websites and apps, making it useful for research, outreach, and content tasks.
- Web and form automation: The browser handles data scraping, form filling, and content submission with minimal input. It performed well on structured, simple pages, such as newsletter directories and submission sites.
- Persistent memory: Fellou stores scraped data locally, enabling it to reuse information in future runs. This saves time and reduces the cost associated with repeating tasks.
- Structured research output: In tasks like compiling YC startup data, Fellou pulled from multiple sources and returned structured, usable results. It can navigate multiple domains and platforms, which is helpful for complex research assignments.
- Spark estimates: Before executing, Fellou estimates how many Sparks a task will consume. This helps users manage usage and plan workflows within their credit limits.
Cons
- Struggles with complex webpages: Dynamic or irregular page layouts can cause execution loops or step failures. Fellou is not yet reliable enough for sites that rely on heavy JavaScript or real-time DOM changes.
- CAPTCHA limitations: The browser cannot solve CAPTCHAs or bypass human verification gates, which restricts its use on many modern websites.
- Execution reliability: While Fellou works well on repeatable, structured tasks, it’s not fully reliable for hands-off automation. Users may need to monitor and intervene during workflows.
- Early-stage stability: The tool shows promise but lacks the polish of mature automation platforms. Competing agents like Claude’s Computer Use and upcoming tools like Chrome’s native agent and Perplexity Comet may offer more stability in the future.
Fellou Browser Security Concerns
Fellou’s agentic architecture, designed to take autonomous actions across the web and system on behalf of the user, also introduces new security risks. Unlike traditional browsers that treat webpage content as untrusted and sandboxed, Fellou forwards visible webpage text directly to its language model for processing, along with user queries. This breaks conventional web security boundaries and exposes users to prompt injection attacks.
A notable example is a vulnerability discovered in August 2025, where attackers could embed malicious instructions in the visible content of a website. When a user asked Fellou to visit the site, the browser passed that content to the AI agent as input. The language model then interpreted the embedded instructions as part of its task, enabling actions such as sending emails, visiting external sites, or leaking sensitive data.
The issue stems from a deeper design flaw common to agentic browsers: the failure to separate trusted user input from untrusted web content when constructing prompts for the language model. Since the AI agent acts with broad privileges and across domains, traditional protections like the same-origin policy are bypassed. This means an attacker can hijack the AI’s behavior by injecting natural-language instructions into content that appears harmless to the user.
Fellou was notified of the vulnerability in August and it was publicly disclosed in October 2025. While it demonstrates some resistance to hidden or invisible prompt injections, the incident highlights the broader systemic challenge of securing agentic AI systems.
AI Browser Security with Seraphic
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