Four Line

Stop pasting the same prompt into 5 tabs. Ask every AI at once, compare answers side-by-side, and save what works.

Stop pasting the same prompt into five tabs. Four Line turns your new-tab page into an AI workspace: run multiple AI assistants side-by-side, send one 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 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. 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 sent as a file the AI reads — for full documents and codebases). Broadcast handles each service's unique editor format automatically, and a history sidebar keeps every past broadcast with links back to each conversation. ISOLATED SESSIONS PER WORKSPACE Every workspace 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 sessions bleeding across workspaces. Same for the independent dock tabs at the bottom. WORKSPACES YOU CAN READ AT A GLANCE Save a set of assistants as a named workspace — a "Code review" set, a "Writing" set. Each workspace pill shows the icons of the AIs inside it, so you recognize it instantly. Double-click the name to rename it in place. Lock a workspace to prevent accidental edits. Switch contexts in one click. SIDE PANEL — AI WITHOUT LEAVING THE PAGE Pin Four Line to Chrome's native side panel and chat with any assistant while you read. Highlight text on any page, right-click, and "Send selection to Four Line" drops it straight into the composer. NOTES WITH PROJECTS AND RICH TEXT A real notes library — multiple notes organized into projects 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 switch between writing and reading mode. PROMPT LIBRARY Save reusable prompts and drop them into any AI pane with one tap — or insert directly into the active chat via the per-pane Insert Prompt button. No clipboard juggling. SAVE FROM ANY WEBPAGE Highlight text anywhere, 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. KEYBOARD-FIRST ⌘/ (Ctrl+/) opens the full shortcut sheet. ⌘\ toggles split view, ⌘K opens the broadcast composer, ⌘⇧\ pins the sidebar. Shortcuts work even while you're typing inside a chat pane. EDIT TAB URLS INLINE Right-click any pane and choose "Edit URL…" to jump to a specific saved conversation without leaving the workspace. URLs persist per workspace, so each one remembers exactly where you left off — even after a full browser restart. INFORMATIVE LOADING AND ERROR STATES Slow connection? You see elapsed time, your current bandwidth, and a Reload / Open in Browser escape hatch. If a page refuses to load inside the workspace, you get a clear message and a way out — never a silent blank pane. DARK, LIGHT, AND SYSTEM THEME The whole UI follows your OS theme by default. Override it in Settings. WORKSPACE EXPORT AND IMPORT (PRO) Move your full setup — workspaces, tabs, notes, prompts — between machines with a single 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. $1.30/month or $9.99/year. Sign in once and your license follows you across devices. ━━━━━━━━━━━━━━━━━━━━ WHO IT'S FOR ━━━━━━━━━━━━━━━━━━━━ — Engineers who want the same code question run 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 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 — removes framing restrictions (X-Frame-Options and CSP frame-ancestors) only inside Four Line's own panes, so supported AI sites can render side-by-side. It does not change those sites when you open them in a normal tab, and it never reads or logs your browsing 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" and "Send selection" right-click items. storage — saves your tabs, workspaces, 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 — account sign-in for the Pro tier, using chrome.identity (no third-party SDK, no popup). sidePanel — powers the side-panel surface. host permissions for supported AI services — required to load them inside panes. ━━━━━━━━━━━━━━━━━━━━ WHAT'S DIFFERENT ━━━━━━━━━━━━━━━━━━━━ 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 go as attached files where the service supports it. 2. A workspace, not a launcher. Workspaces, locked layouts, persistent state, your own notes and prompts — it's a place to do work. 3. Per-workspace AI sessions. Each workspace's instance of a provider is fully independent — different conversations, different scroll positions, different histories. Most extensions reparent a single frame 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, workspaces, 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 a secure authentication service (used solely to verify your identity if you upgrade to Pro) and a payment provider (billing and subscription state). No analytics, no telemetry, no advertising IDs. 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