Four Line

One prompt, every AI. Side-by-side ChatGPT, Claude, Gemini, Grok & Kimi with shared notes, prompts, and broadcast.

Four Line is an AI workspace that lives on your new-tab page. Run multiple AI assistants side-by-side, broadcast the same prompt to all of them at once, and keep your prompts and notes in a single library that travels with you. Built for people who use more than one AI every day — researchers comparing model outputs, developers debugging across providers, writers stress-testing drafts, and anyone tired of juggling five tabs and copy-pasting the same question into each one. ━━━━━━━━━━━━━━━━━━━━ WHAT YOU GET ━━━━━━━━━━━━━━━━━━━━ SIDE-BY-SIDE AI PANES Open up to four AI assistants at once in any combination. Drag to resize. Switch single-pane or split-view per workspace. Each pane keeps its login, history, scroll position, and chat conversation when you switch. Supports all major providers — including free-tier and subscription models from both US and international services. ISOLATED SESSIONS PER WORKSPACE New in v1.2: every group gets its own copy of every AI. Your "Code" workspace can have one provider pinned to a specific conversation while your "Writing" workspace has that same provider on a totally different chat — no more sessions bleeding across groups. Same for the independent dock tabs at the bottom. BROADCAST — ONE PROMPT, EVERY MODEL Type a question once. Press send. Every visible AI gets the prompt typed into its input field and submitted — you compare answers in real time. Choose Prompt mode (typed into the chat box, any length) or Attachment mode (long text gets sent as a file the AI reads — for full documents and codebases). Broadcast is compatible with all supported providers and handles each service's unique editor format automatically. GROUPS — SCOPED WORKSPACES Save a set of AI assistants as a named "group" — for example, a "Code review" group or a "Writing" group. Switch contexts in one click. Lock a group to prevent accidental edits. Unlimited workspaces on Pro. NOTES WITH PROJECTS AND RICH TEXT A real notes library — multiple notes, organized into projects (folders) you create. The editor supports headings, bold, italic, underline, lists, blockquotes, code blocks, links, and inline images. Paste a screenshot directly into a note. Edit and Preview tabs let you switch between writing and reading mode. PROMPT LIBRARY Save reusable prompts. One tap to copy them into any AI pane. Insert directly into the active chat via the per-pane Insert Prompt button — no clipboard juggling. SAVE FROM ANY WEBPAGE Highlight text on any page, right-click, and choose "Save to Four Line as Note" or "Save as Prompt". Pick a title, and it lands in your library with a link back to the source. Works on any site, not just AI services. SWITCH GOOGLE ACCOUNTS QUICKLY Right-click a Gemini or AI Studio tab, choose "Switch Google Account…", and enter the account index (0, 1, 2…). The pane reloads to that account's workspace — no more cookie wrestling. EDIT TAB URLS INLINE Right-click any pane and choose "Edit URL…" to navigate to a specific saved conversation without leaving the workspace. URLs persist per group, so each workspace remembers exactly where you left off — even after a full browser restart. INFORMATIVE LOADING UI Slow connection? You see elapsed seconds, your current bandwidth, and after fifteen seconds a Reload and Open in Browser escape hatch — no more staring at a silent spinner wondering whether the service is down or your wifi is. DARK, LIGHT, AND SYSTEM THEME The whole UI follows your OS theme by default. Override per-preference in Settings. WORKSPACE EXPORT AND IMPORT (PRO) Move your full setup — groups, tabs, notes, prompts — between machines with a single JSON file. ━━━━━━━━━━━━━━━━━━━━ FREE AND PRO ━━━━━━━━━━━━━━━━━━━━ Four Line is free forever for four AI providers, two workspaces, two tabs per workspace, ten notes, ten prompts, and one image per broadcast. No trial, no card up front. Pro unlocks unlimited AI providers, unlimited workspaces and tabs, unlimited images per broadcast, unlimited notes and prompts, long-text broadcast attachments, and workspace export/import. $9.99/month or $79.99/year, billed by Polar. Sign in with Google once and your license follows you across devices. ━━━━━━━━━━━━━━━━━━━━ WHO IT'S FOR ━━━━━━━━━━━━━━━━━━━━ — Engineers who want to run the same code question past multiple models before trusting any one answer — Researchers comparing outputs across providers at scale — Writers who want a second (and third, and fourth) opinion on a draft — Power users who'd rather have one focused workspace than fifteen pinned tabs ━━━━━━━━━━━━━━━━━━━━ HOW IT WORKS ━━━━━━━━━━━━━━━━━━━━ Four Line replaces your new-tab page with a workspace. Pick the AI assistants you want, group them however you like, and that view becomes home. Logins persist via each service's own cookies — Four Line never sees your credentials and never reads your conversations. Permissions explained: declarativeNetRequest — strips X-Frame-Options and CSP frame-ancestors from supported AI sites so they can render inside panes (the same approach every multi-AI extension uses; we don't read your traffic). webNavigation — tracks which page each pane is on so your chosen URL and account persist after a refresh or browser restart. contextMenus — powers the "Save selection as Note / Prompt" right-click items. storage — saves your tabs, groups, prompts, and notes locally. activeTab and scripting — opens the save dialog when you right-click a selection. Activated only at click time, on the tab you clicked. identity — Google sign-in for the Pro tier, using chrome.identity (no third-party SDK, no popup). host_permissions for supported AI services — required to load them inside panes. ━━━━━━━━━━━━━━━━━━━━ WHAT'S DIFFERENT ━━━━━━━━━━━━━━━━━━━━ There are other multi-AI extensions. Here is what sets Four Line apart: 1. Real broadcast. Most multi-AI tools just open multiple tabs. Four Line types the same prompt into the actual input element of each service and clicks Send — you get answers from all of them from one keystroke. Long prompts get sent as attached files when the service supports it. 2. Workspace, not just tabs. Groups, locked layouts, persistent state, your own notes and prompts — it's a place to do work, not a launcher. 3. Per-workspace AI sessions. Each group's instance of a provider is fully independent — different conversations, different scroll positions, different histories. Most extensions reparent a single iframe across groups and you lose your place every time you switch. 4. A real notes library. Most extensions ship a textarea and call it notes. Four Line gives you projects, a rich text editor, and image support. 5. Honest free tier. Four providers and two workspaces are enough to use the app daily without paying. Upgrade only when you outgrow it. ━━━━━━━━━━━━━━━━━━━━ PRIVACY ━━━━━━━━━━━━━━━━━━━━ Your workspace data — tabs, groups, prompts, notes, theme — lives entirely in your browser's local storage. Four Line never reads your AI conversations, never sees the text you broadcast, and never stores any of it on a server. The only Four Line servers in the loop are Firebase Authentication (used solely to verify your Google identity if you upgrade to Pro) and Polar (which handles billing and subscription state). No analytics, no telemetry, no advertising IDs. The extension does not phone home for any other reason. Your conversations with each AI provider are governed by that provider's own policies. Privacy: https://fourline.ai/privacy Terms: https://fourline.ai/terms Support: https://fourline.ai/contact