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SPECIFICTION
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Tandem Browser

tandembrowser.org

Free plan WindowsmacOSLinuxAPI
Visit tandembrowser.org
Spec score 7.5 #11 of 18 in Browser Agents

What it is

Tandem Browser is a free, MIT-licensed browser in developer preview for running AI agents alongside a person’s browsing session. Agents share tabs, cookies, and the DOM, and can work with the accessibility tree, rendered DOM, network requests, console output, and DevTools. If an agent reaches a CAPTCHA, unclear form, or judgment call, it pauses for user help. MCP- or HTTP-speaking agents can connect locally or through a private Tailscale network, with separate workspaces and tab locks. The documented API includes more than 280 HTTP endpoints and 257 MCP tools, protected by bearer tokens. Tandem has no cloud backend, subscription, or telemetry according to its FAQ; browsing data remains on the machine unless sent elsewhere. It can run offline with Ollama or LM Studio. Daily-driver features include extensions, bookmarks, history, a local password vault, workspaces, and sidebar apps. It uses Chromium and supports macOS Apple Silicon, Windows 11 x64, and Linux on a best-effort basis.

Spec sheet

Product
Tandem Browser is an open-source, local-first browser where AI agents share the user's browser session, tabs, cookies, and DOM.Read 30 Sep 2026 · tandembrowser.org
Audience
The maker describes the product as aimed at AI power users, MCP builders, privacy-minded operators, and teams exploring browser agents.Read 30 Sep 2026 · tandembrowser.org
Platforms
The FAQ lists macOS Apple Silicon and Windows 11 x64 as supported, with Linux described as best-effort; it says macOS builds are signed and notarized while Windows builds are unsigned.Read 30 Sep 2026 · tandembrowser.org
API
The API page documents more than 280 HTTP endpoints and 257 MCP tools, with bearer-token authentication.Read 30 Sep 2026 · tandembrowser.org
Security
The maker describes an eight-layer security pipeline with an 811K-plus-entry blocklist, YARA-style rules, AST fingerprinting, entropy detection, and 51 automated tests.Read 30 Sep 2026 · tandembrowser.org
Support
The maker directs users to GitHub Discussions for questions and troubleshooting, and GitHub issues for bugs and concrete feature requests.Read 30 Sep 2026 · github.com
Agent connections
Agents can connect on the same machine or remotely over a private Tailscale network; each agent can have its own workspace, with tab locks to prevent conflicts.Read 30 Sep 2026 · tandembrowser.org
Browser features
The maker lists workspaces, extensions, bookmarks, history, a local password vault, and sidebar apps among its daily-driver browser features.Read 30 Sep 2026 · github.com
Data handling
The FAQ says there is no Tandem Browser cloud backend, subscription, or telemetry, and that browsing data stays on the user's machine unless they choose to send it elsewhere.Read 30 Sep 2026 · tandembrowser.org
Human handoff
When an agent encounters a CAPTCHA, unclear form, or judgment call, it pauses and asks the user for help.Read 30 Sep 2026 · tandembrowser.org
License and stage
The site identifies Tandem Browser as MIT licensed and in developer preview.Read 30 Sep 2026 · tandembrowser.org
Model integrations
The maker says agents that speak MCP or HTTP can connect, including Claude, GPT, Gemini, OpenClaw, Ollama, LM Studio, and custom scripts.Read 30 Sep 2026 · tandembrowser.org
Offline use
The FAQ says Tandem Browser can run fully offline when used with a local model such as Ollama or LM Studio.Read 30 Sep 2026 · tandembrowser.org
Page access
Agents can work with the accessibility tree, rendered DOM, network requests, console output, and DevTools.Read 30 Sep 2026 · tandembrowser.org
Sidebar integrations
The repository lists Telegram, WhatsApp, Discord, Slack, Gmail, Calendar, Instagram, and X as sidebar apps.Read 30 Sep 2026 · github.com

Plans and prices

Free Free Free and open source · no subscription Read 30 Sep 2026 · tandembrowser.org

Every Tandem Browser plan and price →

Strong points and limits

Strong points

  • Free and open source
  • More than 280 HTTP API endpoints
  • 257 documented MCP tools
  • Offline use with local models
  • Separate workspaces and tab locks

Limits

  • Still in developer preview
  • Linux support is best-effort
  • No free trial because plan is free

Who it suits

It suits AI power users, MCP builders, privacy-minded operators, and teams exploring browser agents. It also fits users wanting local or offline browser automation.

Verdict

Tandem Browser combines a local browser session with extensive agent access and a documented API. Its developer-preview status and best-effort Linux support are the main constraints to consider.

Where Specifiction places it

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