Four Line

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 AI in the current workspace 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. KEYBOARD-FIRST Jump straight between panes without touching the mouse: Ctrl+Alt+1 through 4 focus a pane and drop your cursor right into that assistant's message box, and Ctrl+Alt+← / → cycle through them. ⌘/ (Ctrl+/) opens the full shortcut sheet, ⌘\ toggles split view, ⌘K opens the broadcast composer, ⌘⇧\ pins the sidebar. Shortcuts keep working even while you're typing inside a chat pane. 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. 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. Free also includes the independent dock at the bottom: open any provider there — including the Pro-only ones — one tab at a time, so you can try everything before deciding. 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. Single purpose: Four Line does one thing — it puts multiple AI assistants side-by-side in one workspace. It does not include a web search feature, and it does not change your default search engine or any other browser setting. Permissions explained: declarativeNetRequest and declarativeNetRequestWithHostAccess — remove framing restrictions (X-Frame-Options and CSP frame-ancestors) only for the frames Four Line itself creates inside its workspace, so supported AI sites can render side-by-side. These rules do not apply when you open those sites normally in a browser tab, and they never read or log your browsing traffic. webNaviga…