Atlas vs Copilot Mode vs Dia vs Comet Agentic AI Browsers in 2025: Which One Is Right for You?

Agentic AI browsers are fundamentally transforming how we interact with the web—evolving from simply "answering questions about web content" to "actively operating on the web itself." In 2025, four agentic AI browsers stand out from the pack: OpenAI's ChatGPT Atlas, Microsoft Edge with Copilot Mode, The Browser Company's Dia, and Perplexity's Comet. Each has made distinct design choices regarding autonomy, memory capabilities, and privacy protections. This article provides an in-depth analysis of their architectures, features, and risk profiles to help different types of users identify which browser best aligns with their workflows.

What are Agentic AI Browsers?

Agentic AI browsers represent a paradigm shift in web browsing technology. Unlike traditional browsers that simply render web pages or conventional AI chatbots that merely answer questions about web content, agentic browsers are not just "chat over a page." They expose the browser's DOM (Document Object Model), tab graph, and browsing history to an AI model, enabling them to:

• Read and reason across multiple tabs - Understanding context from multiple sources simultaneously
• Maintain task context over time - Remembering your goals and progress across sessions
• Take actions on your behalf - Navigating, filling forms, clicking buttons, and completing complex workflows

For users seeking the best agentic AI browser for automation, it's important to understand that OpenAI ChatGPT Atlas, Microsoft Edge Copilot Mode, The Browser Company's Dia, and Perplexity's Comet all possess these capabilities, but they make different tradeoffs in terms of autonomy, memory, and security. The key distinction is moving from passive information retrieval to active web operation—these browsers don't just tell you about the web, they work on the web for you.

High-Level Comparison

Before diving into the technical details, here's how these four agentic AI browsers compare at a glance:

Atlas is the most fully agentic: deep ChatGPT integration, rich browser control, strong but complex memory and privacy story.

Copilot Mode is an incremental but significant extension to Edge: unified Copilot, cross-tab reasoning, early 'Actions' for automation, still conservative compared with Atlas and Comet.

Dia is an AI-first browser built on Chromium, optimized for reading, writing, and structured workflows with privacy-first defaults and intentionally limited autonomy.

Comet is a highly agentic personal assistant browser with deep workflow automation, a local-data narrative, and currently the most aggressive legal and security risk profile.

The rest of the article unpacks these differences in greater technical depth.

1. ChatGPT Atlas (OpenAI): AI-Native Browser with Full Agent Mode

1.1 Architecture

Atlas isn't simply a standard Chromium shell with an extension—it's a dedicated AI browser built around ChatGPT. While based on Chromium, it employs OpenAI's OWL process architecture, which separates the rendering engine from the Atlas application and agent layers.

Key Characteristics:

• Currently macOS only at launch, with Windows, iOS, and Android versions "coming soon"
• ChatGPT is integrated everywhere: omnibox, main panel, and a ChatGPT sidebar that can observe the current page and tabs
• Provides first-class API access to:Current tab DOM and visible contentTab list and navigation historyUser queries and previous conversation state
  • Current tab DOM and visible content
  • Tab list and navigation history
  • User queries and previous conversation state

1.2 Agent Mode: Genuine Browser Control

Agent Mode is the key differentiating feature. For Plus/Pro/Business users, Atlas can execute multi-step workflows:

• Open and close tabs, follow links, switch between sites
• Fill out forms and online applications
• Book hotels, restaurants, and other services
• Compare products across multiple sites and return structured summaries

These capabilities make Atlas particularly compelling as an agentic AI browser with workflow automation, allowing users to delegate complex, multi-step tasks that would normally require significant manual effort.

Constraints:

• Agent mode cannot access local files or the operating system, and cannot download or execute local programs. It's sandboxed within the browser
• Actions require explicit user consent; Atlas displays prompts like "Should I start clicking and filling these forms?" before executing workflows

1.3 Memory and Privacy

Atlas introduces browser memories:

• It stores filtered summaries of visited pages and inferred user intent, not full page captures. Summaries are retained for approximately 30 days, enabling queries like "reopen the reports I read yesterday" or "continue the Athens itinerary plan"
• Memories are opt-in and can be viewed, edited, or deleted. Memory can be disabled globally or on specific sites, and Atlas supports incognito mode
• OpenAI has also added parental controls that allow guardians to disable both browser memories and agent mode for child accounts

Critical Considerations:

• Atlas still needs to transmit page snippets and metadata to OpenAI's servers for summarization, meaning sensitive content could be exposed if protections fail
• Security researchers have already demonstrated prompt-injection attacks exploiting Atlas's omnibox and agent context, confirming that highly agentic browsing increases the attack surface

1.4 Pricing and Target Users

• Atlas is free to install for ChatGPT users on macOS
• Agent Mode is only available on paid ChatGPT tiers (Plus, Pro, Business, Enterprise)

Best For:

Users who want maximum in-browser automation and are comfortable with cloud-centric data handling and an evolving security posture.

2. Microsoft Edge with Copilot Mode: Tab Reasoning with Controlled Autonomy

2.1 Architecture

Copilot Mode is Microsoft's AI layer within Edge, not a separate browser. It provides:

• A unified Copilot box on new tabs for chat, search, and navigation
• Deep integration with Edge context (open tabs, history, and some browser settings) when users opt in
• Microsoft also integrates Copilot Mode with:Journeys: Topic-centric clusters over browsing history that Copilot can summarize and reopenCopilot Actions: An early agentic layer capable of actions like clearing cache, unsubscribing from mailing lists, and booking reservations (in preview)
  • Journeys: Topic-centric clusters over browsing history that Copilot can summarize and reopen
  • Copilot Actions: An early agentic layer capable of actions like clearing cache, unsubscribing from mailing lists, and booking reservations (in preview)

2.2 Agentic Behavior

Compared to Atlas:

• Copilot Mode can reason across multiple tabs, summarize and compare them, and assist with structured tasks like trip planning or multi-site research
• Actions Preview extends this into partially agentic flows such as booking restaurants or filling forms, but current evaluations show inconsistent reliability and occasional "hallucinated" completions of tasks not actually executed

Crucially, Copilot Mode remains more constrained than Atlas or Comet:

• It doesn't expose an openly programmable DOM-level agent with free cursor control
• Action templates are narrower and more guarded, particularly for email and account-sensitive operations

2.3 Data, Privacy, and Enterprise Positioning

Edge with Copilot Mode is clearly targeted at enterprise adoption:

• Copilot access to tab and history data is explicitly permissioned; users can disable history-based personalization, Copilot context, and Copilot Mode entirely
• Microsoft integrates Prompt Shields and Azure AI safety layers to mitigate prompt injection and jailbreak attempts

Best For:

Organizations that want AI-assisted browsing and cross-tab reasoning while keeping automation scoped and more auditable than a fully agentic browser.

3. Dia (The Browser Company): AI-First, Chromium-Based, Privacy-Forward

3.1 Architecture and User Experience

Dia is The Browser Company's AI-centric successor to Arc, built on Chromium and currently available on macOS only.

Core Design Choices:

• The canonical interaction is "chat with your tabs": Dia's assistant can read open tabs, referenced tabs, and selections, answering questions or transforming content in place
• Dia includes a Skills system where users define reusable prompt "scripts" and workflows for tasks like note-taking or research templates
• Dia's UX is optimized for:Reading and understanding long-form contentIn-page writing and editingLearning workflows (tutoring, flashcards, argument comparison)
  • Reading and understanding long-form content
  • In-page writing and editing
  • Learning workflows (tutoring, flashcards, argument comparison)

3.2 Memory and "Local-First" Privacy

Dia's primary differentiation is its privacy stance:

• Browsing history, chats, bookmarks, and saved content are stored locally and encrypted, with data sent to servers only when required to answer a specific query
• The Memory feature stores summaries and learned preferences, but users can disable memory entirely in settings or control what contexts are shared
• The net effect is an AI browser that behaves more like a local knowledge layer with scoped cloud calls rather than a continuous telemetry stream

3.3 Agentic Scope and Constraints

Dia is intentionally less agentic than Atlas or Comet:

• The assistant can read and summarize pages, transform text, generate content, and run Skills over the current tab set
• Current public builds don't expose a general DOM automation agent capable of open-ended clicking and form submission across arbitrary sites
• In practice, Dia behaves as a high-context copilot rather than a fully autonomous web operator. This aligns with the company's positioning and with Atlassian's stated intent after acquiring The Browser Company, which emphasizes individual knowledge worker workflows over transactional automation

For those researching agentic AI browsers for privacy-focused users, Dia represents a deliberately conservative approach that prioritizes user control and data protection over maximum automation capabilities.

3.4 Pricing and Availability

• Dia now ships to all Mac users, no invite required, as of October 2025
• Free tier: Core AI chat, Skills, and Memory, with usage limits
• Dia Pro at $20/month unlocks effectively unlimited AI chat usage within terms of use

Best For:

Users with educational and writing-heavy workflows who want AI-augmented browsing without granting an agent broad control over their web session.

4. Comet (Perplexity): Highly Agentic Assistant Browser with Heavy Risk Surface

4.1 Architecture and Capabilities

Comet is Perplexity's AI browser built on Chromium, positioned as a personal AI assistant and "thinking partner" rather than a simple search UI.

The Comet Assistant Can:

• Summarize and explore any page
• Execute multi-step workflows for research, coding, meeting prep, and e-commerce
• Manage email and calendar via integrated connectors
• Handle complex tasks like comparing products, reading reviews, and proceeding all the way to checkout

Recent updates extend the agent to work longer and across larger jobs, emphasizing persistent, agentic behavior across many tabs and time periods. As one of the most advanced agentic AI browsers for research and shopping, Comet pushes the boundaries of what automated browsing can accomplish, though this comes with corresponding security considerations.

4.2 Data Model and Privacy Claims

Perplexity's Comet Privacy Notice and product pages claim:

• Browsing data, cookies, and saved credentials are stored locally on the device by default
• Users can delete browsing data and stored credentials from Comet settings and manage cookie behavior
• Integration with 1Password keeps vaults end-to-end encrypted and opaque to Perplexity

So the official architecture is hybrid: local browser state with selective context uploads to Comet's servers and Perplexity's search models.

However, multiple independent reviews argue that despite these controls, the combination of deep integration with third-party services (Gmail, calendar, financial accounts) and high agent autonomy over those services produces a large effective privacy risk envelope, especially for corporate data.

4.3 Security Incidents and Legal Pressure

Comet currently has the most visible security and legal issues among the four:

• Indirect Prompt-Injection / "CometJacking": LayerX and other researchers demonstrated that malicious URLs and embedded prompts could hijack Comet's assistant, exfiltrating data from connected services and even performing fraudulent actions
• Although Perplexity has patched specific vulnerabilities, security audits from Brave, Guardio, and others still recommend extreme caution for sensitive workloads
• Amazon Lawsuit: Amazon is suing Perplexity over Comet's "agentic shopping" behavior, alleging that automated shopping sessions accessed customer accounts and impersonated human browsing, violating platform rules and harming personalization systems

4.4 Pricing and Availability

• As of October–November 2025, Comet is free to download globally; earlier Max-only and Pro-only restrictions have been removed
• Perplexity monetizes via Pro/Max subscriptions for higher model tiers and via Comet Plus (~$5/month), which grants access to curated news and publisher content and is bundled into Pro/Max

Best For:

Power users who want maximum automation across research, communications, and purchases, and who are comfortable operating at the bleeding edge of the security and platform-policy risk curve.

Comparison Table

Which Browser Should You Choose in 2025?

When evaluating agentic AI browsers for enterprise use or personal productivity, consider these recommendations:

Choose Atlas when you want to explore the frontier of in-browser agents. It offers the richest action surface and memory model, at the cost of greater complexity in safety and compliance design.

Choose Edge + Copilot Mode when you need incremental AI assistance in a browser that already fits Microsoft-centric enterprise governance, and you prefer scoped agents over unconstrained ones.

Choose Dia when your primary workload is reading, learning, and writing, and you want strong local-first guarantees and explicit control over what information the model sees, with minimal automation.

Choose Comet only if you explicitly want a high-autonomy personal operator in your browser and are willing to track security advisories and platform policies closely.