Assertify

Assertify

Let your AI agent use any website you're logged in to.

Log in once. Your session stays encrypted on your machine. Claude, Codex, Cursor and any MCP client can then browse, click, type and read for you.

Quick start · Connect your client · Tools · Security · FAQ

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You:    Check my LinkedIn messages and summarize anything from recruiters.

Agent: open_session("linkedin") → click "Messaging" → read_text … You have 3 recruiter messages. The most recent is from Dana at Acme, about a Senior QA role …

✨ Why Assertify

Most sites have no API, or one that can't do what you need. Assertify gives your agent a real browser that is already logged in as you, without ever handing it your password.

• 🔐 Log in once, by hand. A normal browser window opens; you sign in (2FA, passkeys, SSO all work). The agent never sees your password.
• 🧳 Encrypted, local, yours. Sessions are AES-256-GCM encrypted with a key in your OS keychain. Assertify itself sends nothing anywhere. There is no server and no account.
• 🤖 Works with every MCP client. Claude Code, Claude Desktop, Codex, Cursor, VS Code, Gemini CLI, Grok, Windsurf…
• 👀 See what the agent sees. Every step can come with a screenshot, shown in the chat and saved to disk.
• 🛡️ Fenced in. Each login is locked to its own domains, so a prompt injection on a page can't walk your logged-in browser somewhere else.
• 👥 Many accounts per site. Five Gmail accounts? Log in to each; they're named after their emails. Use one, or open them all at once.
• ✋ Asks before it acts. Buttons that send, post, buy, delete or connect are paused until you say yes. Logins can be made read-only.
• 🧍 Behaves like a person. Real Chrome, your own browser fingerprint, curved mouse moves, uneven typing and natural pauses. No navigator.webdriver flag.
• 📎 Uploads files and folders. Photos for a Facebook post, a PDF for an email: the agent clicks the upload button and picks your files, just like you would. Key and password files are always refused.
• 🪟 Handles pop-ups. Cookie banners are declined for you; "share your contact info" style pop-ups are flagged so the agent decides, or closes them.
• 🔁 Hands back to you when needed. CAPTCHAs, 2FA prompts and expired logins open in a window for you to finish; the agent then carries on.
• 🪶 Fast and token-cheap. The agent reads a compact outline ([e12] button "Send"), not raw HTML.

⚙️ How it works

flowchart LR

U(["👤 You"]) -- "log in once per account" --> L["Login window real browser, 2FA works "] L -- "named by email" --> V K[["🔑 OS keychain macOS · Windows · Linux "]] -. key .-> V

subgraph V["🔒 Encrypted vault"] direction LR P1["personal@gmail.com"] P2["work@gmail.com"] P3["shop@gmail.com"] P4["you@company.com LinkedIn "] end

V -- decrypt --> S["⚙️ Assertify server asks before send · buy · delete "] A(["🤖 AI agent"]) <-- "pick one account or all at once" --> S S -- "side by side" --> B

subgraph B["Headless browsers, logged in"] direction LR H1["Gmail · personal@"] H2["Gmail · work@"] H3["Gmail · shop@"] end

classDef person fill:#eef2ff,stroke:#6366f1,color:#1e1b4b classDef safe fill:#ecfdf5,stroke:#10b981,color:#064e3b classDef live fill:#fff7ed,stroke:#f97316,color:#7c2d12 class U,A,L,S person class P1,P2,P3,P4,K safe class H1,H2,H3 live style V fill:#f0fdf4,stroke:#10b981 style B fill:#fffbeb,stroke:#f59e0b

Log in once per account; each one is saved under its email. Your agent then opens one account by name, or every account for a site at once, each in its own logged-in browser. Everything above runs on your computer, on macOS, Windows or Linux.

🚀 Quick start

You need uv:

• macOS / Linux: curl -LsSf https://astral.sh/uv/install.sh | sh
• Windows (PowerShell): powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

git clone https://github.com/romaklym/assertify.git

cd assertify uv sync uv run assertify setup

setup downloads the browser (Chromium, about 300 MB, once), checks your keychain, and prints the exact command to connect your AI client. If you skip it, Assertify downloads the browser on first use, or falls back to your installed Chrome or Edge.

Linux notes

• If the browser won't start, install its system libraries: sudo uv run playwright install-deps chromium.
• The key goes in Secret Service (GNOME Keyring or KWallet). On a server with no keychain, set ASSERTIFY_PASSPHRASE instead.
• Logging in needs a screen for the browser window. On a server, log in on your desktop and copy ~/.assertify-mcp over (with the same passphrase), or use ssh -X.

Then save your first login:

uv run assertify login github https://github.com/login

A browser window opens. Sign in, then close the window (or press Enter in the terminal). Done. Your agent can now use GitHub as you.

[!TIP]

You can also just ask your agent: *"log me in to Notion"*. It calls start_login, the window opens, and the session saves when you close it.

🔌 Connect your AI client

Replace /path/to/assertify with where you cloned it (assertify setup prints the exact line for you).

Claude Code

claude mcp add -s user assertify -- uv --directory /path/to/assertify run assertify serve

Claude Desktop

Easiest: download assertify.mcpb and double-click it. Claude Desktop installs it with its icon and handles Python for you.

Or add it to claude_desktop_config.json by hand:

{

"mcpServers": { "assertify": { "command": "uv", "args": ["--directory", "/path/to/assertify", "run", "assertify", "serve"] } } }

</details>

Codex

codex mcp add assertify -- uv --directory /path/to/assertify run assertify serve

or in ~/.codex/config.toml:

[mcp_servers.assertify]

command = "uv" args = ["--directory", "/path/to/assertify", "run", "assertify", "serve"]

</details>

Cursor

~/.cursor/mcp.json:

{

"mcpServers": { "assertify": { "command": "uv", "args": ["--directory", "/path/to/assertify", "run", "assertify", "serve"] } } }

</details>

VS Code (Copilot)

.vscode/mcp.json:

{

"servers": { "assertify": { "type": "stdio", "command": "uv", "args": ["--directory", "/path/to/assertify", "run", "assertify", "serve"] } } }

</details>

Gemini CLI, Grok, Windsurf, Zed and others

Any client that runs local (stdio) MCP servers works. Use this command:

uv --directory /path/to/assertify run assertify serve

For JSON configs, use the mcpServers block shown under Cursor.

🧰 Tools

👀 Seeing what the agent sees

Ask *"show me a screenshot"* or *"open my GitHub session with screenshots on so I can follow along"*. Images appear in the chat in clients that show them, and every one is saved to ~/.assertify-mcp/screenshots/ /NNN- .jpg. The folder is private to you and cleared after 7 days.

👥 Several accounts on one site

Log in once per account. Leave the name out and Assertify names each login after the email address it finds on the page (falls back to google.com-1, google.com-2… when a site doesn't show one):

assertify login https://mail.google.com   # sign in as you@gmail.com   -> saved as "you@gmail.com"

assertify login https://mail.google.com # sign in as work@gmail.com -> saved as "work@gmail.com" assertify login work https://mail.google.com # or pick the name yourself assertify list google.com # just the Google logins assertify rename google.com-1 side-project

Then just ask:

• *"Check my work@gmail.com inbox"*: the agent opens that one login.
• *"Any unread mail in any of my Gmail accounts?"*: the agent calls open_sessions(site="google.com") and gets one session per account, which it can work through side by side.

Each account lives in its own encrypted file and its own isolated browser, so cookies never mix. On sites that restrict automation, avoid running the same action on many accounts at once.

📎 Uploading files

Tell your agent what to upload and where:

*"Post the photos in ~/Pictures/trip to my Facebook with the caption 'Back home'"*

The agent opens the composer, calls upload_files(paths=["~/Pictures/trip"], text="Photo/video"), writes the caption, then asks you before pressing Post. Under the hood:

1. File dialog first. It clicks the upload button with a natural mouse move and picks the files in