Agentic Browser Showdown 2025: Atlas vs Copilot Mode vs Dia vs Comet

What are agentic browsers?

Agentic browsers move beyond "chat about a page" to letting an AI operate inside the browser. They expose page structure, tab relationships, and history to a model so it can read multiple tabs, maintain task context over time, and take actions like navigating, filling forms, or completing workflows. In 2025 the leading examples are OpenAI's ChatGPT Atlas, Microsoft Edge with Copilot Mode, The Browser Company’s Dia, and Perplexity's Comet. Each makes different tradeoffs around autonomy, memory, and privacy.

High-level comparison

Atlas aims to be the most fully agentic with deep ChatGPT integration and broad browser control but a more complex privacy and security story. Edge's Copilot Mode extends an existing browser with cross-tab reasoning and guarded automation aimed at enterprises. Dia focuses on reading, writing, and structured workflows with local-first privacy and intentionally limited autonomy. Comet pursues an aggressive personal-assistant model with heavy automation and a correspondingly larger security and legal risk surface.

1. ChatGPT Atlas (OpenAI)

Architecture

Atlas is built around ChatGPT rather than being a Chromium shell plus an extension. It runs on Chromium but wraps the renderer in OpenAI's OWL process architecture, separating rendering from the Atlas application and agent layer. Atlas currently launched on macOS with Windows, iOS, and Android planned.

Atlas exposes ChatGPT throughout the UI (omnibox, main panel, sidebar) and provides APIs into the current tab DOM, tab list and history, and conversation state.

Agent mode

Agent Mode lets paid users execute multi-step workflows: open and close tabs, navigate sites, fill forms, book reservations, and compare products across pages, returning structured summaries. Actions are sandboxed to the browser and cannot access local files or execute local programs. Agent actions require explicit user consent and Atlas surfaces prompts like 'Should I start clicking and filling these forms' before proceeding.

Memory and privacy

Atlas stores filtered summaries of visited pages and inferred intent rather than full captures, retaining summaries for about 30 days. Memories are opt-in and can be viewed, edited, or deleted; memory can be disabled per-site or globally, and Atlas supports incognito. Parental controls can disable both memories and agent mode for child accounts.

However, Atlas sends page snippets and metadata to OpenAI's servers for summarization, which increases exposure risk if protections fail. Researchers have demonstrated prompt-injection attacks against Atlas's omnibox and agent context, showing that agentic browsing expands the attack surface.

Pricing and fit

Atlas is free to install on macOS for ChatGPT users; Agent Mode is restricted to paid ChatGPT tiers (Plus, Pro, Business, Enterprise). Atlas fits users who want maximal in-browser automation and accept cloud-centric data handling and evolving security tradeoffs.

2. Copilot Mode in Microsoft Edge

Architecture

Copilot Mode is an AI layer inside Edge rather than a separate browser. It provides a unified Copilot box for chat, search, and navigation and can access open tabs, history, and certain settings with user permission. Microsoft integrates Copilot with Journeys (topic-centric clusters over history) and Copilot Actions, an early automation layer for tasks such as clearing cache, unsubscribing, and booking reservations in preview.

Agentic behavior

Copilot Mode can reason across tabs, summarize and compare them, and assist with planning and research. Actions Preview enables partially agentic flows but has shown inconsistent reliability and occasional hallucinated completions. Unlike Atlas or Comet, Copilot Mode does not expose a freely programmable DOM-level agent; templates are narrower and guarded, especially around email and account-sensitive operations.

Data, privacy, and enterprise posture

Copilot Mode is designed for enterprise adoption. Access to tab and history data is permissioned; users and admins can disable history-based personalization and Copilot context. Microsoft layers Prompt Shields and Azure AI safety controls to mitigate prompt injection and jailbreak attempts.

Fit: good for organizations that want AI-assisted browsing with scoped automation and stronger auditability than fully agentic alternatives.

3. Dia (The Browser Company)

Architecture and UX

Dia is an AI-first browser built on Chromium and available on macOS. The canonical interaction is 'chat with your tabs': the assistant can read open and referenced tabs and operate on selections, answering questions or transforming content in place. Dia includes a Skills system where users create reusable prompt scripts and workflows for note-taking, research templates, and other tasks. The UX is optimized for reading, writing, and learning workflows.

Memory and local-first privacy

Dia emphasizes a local-first privacy posture: history, chats, bookmarks, and saved content are stored locally and encrypted. Data is sent to servers only when needed to answer a specific query. Memory stores summaries and preferences but can be disabled or scoped in settings. This results in an AI that behaves more like a local knowledge layer with scoped cloud calls rather than a continuous telemetry stream.

Agentic scope and constraints

Dia intentionally limits agentic autonomy. The assistant can summarize pages, transform text, generate content, and run Skills across the current tab set, but public builds do not expose general DOM automation for open-ended clicking and form submission on arbitrary sites. Dia functions as a high-context copilot rather than a fully autonomous web operator.

Pricing and availability

Dia is available to all Mac users as of October 2025. A free tier covers core AI chat, Skills, and Memory with usage limits; Dia Pro at $20/month unlocks higher usage. Dia is well suited for users focused on writing, learning, and privacy-sensitive knowledge work.

4. Comet (Perplexity)

Architecture and capabilities

Comet is Perplexity's Chromium-based AI browser positioned as a personal assistant rather than a search UI. The Comet Assistant can summarize pages, execute multi-step workflows for research, coding, meeting prep, and e-commerce, and integrate with email and calendars. It can manage complex end-to-end tasks such as comparing products and proceeding to checkout. Recent updates emphasize long-running, persistent agentic behavior across tabs and time.

Data model and privacy claims

Perplexity states that browsing data, cookies, and saved credentials are stored locally by default and can be deleted. Integrations like 1Password keep vaults end-to-end encrypted. The product uses a hybrid model: local browser state with selective uploads to Comet servers and Perplexity's models. Independent reviewers warn that deep integration with third-party services and high agent autonomy can create a large effective privacy risk, especially for corporate data.

Security incidents and legal pressure

Comet has the most visible security and legal issues among the four. Researchers demonstrated indirect prompt-injection attacks ('CometJacking') where malicious pages hijacked the assistant to exfiltrate data and perform fraudulent actions. Perplexity patched vulnerabilities but security audits still urge caution. Amazon is suing Perplexity over agentic shopping behavior, alleging automated sessions accessed accounts and violated platform policies.

Pricing and availability

As of late 2025 Comet is free to download globally, with monetization through Pro/Max subscriptions and a Comet Plus tier. Comet is best for power users who want maximal automation and are prepared to manage security and policy risks.

Choosing an agentic browser in 2025

Pick Atlas for the most powerful in-browser agent and richest action surface if you're comfortable with cloud-based processing and evolving security tradeoffs. Choose Edge + Copilot Mode when you need enterprise-oriented, scoped automation within a Microsoft ecosystem. Use Dia for local-first privacy, reading and writing workflows, and limited automation. Opt for Comet only if you want the most aggressive personal-operator experience and can actively manage security advisories and platform-policy risks.