CoThink is a group chat with AI built in. Invite your family or friends into a room, and start a conversation that never forgets — it remembers every plan, every decision, and every question, so your AI gets smarter as your group does.
Access the best models from every major provider
The Problem
You research something on ChatGPT. Screenshot the answer. Text it to your partner. They have a follow-up. You go back to ChatGPT. Repeat. Forever.
CoThink puts everyone in the same AI conversation from the start. No screenshots. No copy-paste. No being the middleman.
The old way
The CoThink way
Group Chat
Everyone in the room sees the same thread. Ask questions, brainstorm, debate options — the AI responds to your whole group like a helpful teammate who never sleeps.
Permanent Memory
Tap any message to pin it as a “truth” — allergies, budgets, preferences, schedules. The AI carries these facts in every response, so you never re-explain context.
Like pinning a note to the fridge, but the AI actually reads it.
Bookshelf Project
We only have a table saw and a drill
Pinned by Dan
Max board length from the store is 8ft
Pinned by Shannon
Mid-century style, hardwood, tapered legs
Pinned by Dan
Budget is $200 for materials
Pinned by Shannon
Heart any message — the AI always remembers.
Graduation Banquet
Venue max capacity is 120 people
Grandma needs a wheelchair-accessible table
Mom is allergic to shellfish
Catering deposit due by March 28
Car Diagnostics
2019 Honda CR-V, 68k miles
Clicking noise when turning left
Brakes done in January
How It Works
Tap any message to open it in focus mode. Pin the entire message, or highlight just the part you want the AI to remember.
Option 1: Pin the whole message
Select text to pin a specific part, or pin the whole message.
For a mid-century bookshelf, I'd suggest tapered legs and walnut veneer plywood. You can get a full sheet of walnut ply at the store for about $55. With your table saw, you can rip the shelves and sides from one sheet.
Option 2: Pin just a selection
Select text to pin a specific part, or pin the whole message.
For a mid-century bookshelf, I'd suggest tapered legs and walnut veneer plywood. You can get a full sheet of walnut ply at the store for about $55. With your table saw, you can rip the shelves and sides from one sheet.
Option 3: Add from the Lens tab
Facts the AI always remembers.
We only have a table saw and a drill
DanMax board length is 8ft
ShannonEveryday questions
GPT-4o Mini
OpenAI
Gemini Flash
Grok Fast
xAI
DeepSeek V3
DeepSeek
Deep research & writing
Claude Sonnet
Anthropic
GPT-5.3
OpenAI
Gemini Pro
Grok 4.20
xAI
The absolute best
Claude Opus
Anthropic
GPT-5.4
OpenAI
Model Freedom
The AI industry wants you to pick a team. We don't. Switch between GPT, Claude, Gemini, Grok, and DeepSeek — per room, anytime. Use a fast model for quick questions, a frontier model when you need the very best.
One subscription instead of three. And you can try them all before you commit to a plan.
Value
ChatGPT Plus costs $20/mo for GPT only. Claude Pro costs $20/mo for Claude only. That's $60/mo just to compare two providers. CoThink gives you access to all major models for a single flat price — and your whole group shares the plan.
Only the room owner pays. Everyone else joins free.
Separate subscriptions
CoThink Pro
Built Smart
Every AI message costs “tokens” — tiny chunks of text the AI reads and writes. More tokens = more cost. Here's why CoThink is fundamentally smarter about this.
Tokens are fragments of text (~¾ of a word). Every time you message an AI, it reads your tokens in, thinks, and sends tokens back. Both directions cost money.
Most AI apps send your ENTIRE conversation history with every single message. 200 messages deep? The AI re-reads all 200. That's ~50,000 tokens per message.
We automatically compress older messages into smart summaries. The AI gets: system prompt + pinned truths + summary + recent messages. Just ~4,000 tokens total.
You don't configure anything. As conversations grow, CoThink handles compression behind the scenes. Longer chats. Lower costs. Smarter AI.
Other AI apps (300 messages deep)
Full history re-sent every single time
CoThink (300 messages deep)
Smart summary + recent messages + pinned truths
92%
fewer tokens per message
Longer conversations. Lower costs. Smarter AI.
500+ messages compressed into a single summary. Nothing lost, everything optimized.
Pro Tips
Instead of re-stating “Mom is allergic to shellfish” every conversation, pin it once. Saves ~50 tokens per re-statement, per message, forever.
Quick question about dinner? Use a Fast model (pennies). Deep research on your renovation? Switch to Powerful. Match the model to the task.
As your conversation grows, CoThink compresses older messages into smart summaries. You never think about it — it just keeps working.
Having a conversation that's just between humans? Toggle AI off. Zero tokens used. Toggle back on when you need help.
Customizable
Each room has its own system prompt. Turn the AI into a trip planner, a recipe helper, a homework tutor, or a budget advisor. Your “Meal Prep” room gets a cooking expert. Your “Vacation” room gets a travel guide.
Tweak the personality anytime from the Lens tab.
Live Sync
Messages appear instantly for everyone. Typing indicators show who's active. Unread badges tell you what you missed. Jump into any conversation and pick up where your group left off.
Like iMessage, but with AI superpowers.
Human Mode
One tap mutes the AI for your messages. Have a quick sidebar with your partner, then flip AI back on when you need help. The AI catches up on what it missed.
Pricing
Flat monthly plans. No credits, no per-message billing, no surprise charges. Only the room owner pays — members join free.
Perfect for trying CoThink
For active families & couples
For power users & large groups
No credit card required.
Anyone who lives, plans, or dreams with other people.
Coordinate meals, budgets, travel, and life decisions. No more copy-pasting AI answers in your texts.
Example rooms: Meal Prep, Vacation 2026, Budget, Date Night Ideas
Plan trips, manage household logistics, help with homework. One shared AI brain for the whole family.
Example rooms: Family Trip, School Help, Gift Lists, Holiday Plans
Plan events, brainstorm adventures, coordinate group decisions. AI helps everyone, not just the organizer.
Example rooms: Bachelor Party, Book Club, Game Night, Group Trip
Try every major AI model without juggling subscriptions. GPT, Claude, Gemini, Grok, DeepSeek — all in one app.
Example rooms: Model Playground, Research, Writing Lab
If AI feels intimidating, CoThink makes it as simple as texting. No jargon, no command line, no learning curve.
Example rooms: Dinner Tonight, Weekend Plans, Travel Ideas
Brainstorm, research, and problem-solve in dedicated rooms. Each room gets its own AI personality.
Example rooms: Brainstorm, Research Sprint, Project Alpha
No! Only the room owner needs a plan. Everyone you invite chats for free.
We offer models from OpenAI (GPT-4o Mini, GPT-5.3, GPT-5.4), Anthropic (Claude Sonnet, Claude Opus), Google (Gemini Flash, Gemini Pro), xAI (Grok), and DeepSeek. You can switch models per room.
Tokens are how AI measures text (roughly ¾ of a word). CoThink handles token optimization automatically behind the scenes — rolling summaries, smart context compression, pinned truths. You get flat monthly pricing with no per-token charges.
Yes. Your conversations are stored securely in your rooms, protected by row-level security. We don’t train on your data or share it with third parties.
Those are solo AI tools — one person, one conversation. CoThink is shared: your whole group participates in one thread, with access to multiple AI models, pinned facts the AI always remembers, and rooms customized per topic.
Absolutely! Many people create personal rooms for different topics. The multi-model access and pinned truths are great even if you’re the only one in the room. But it really shines when you invite your people.
Your messages aren’t deleted. You can always read your history. Your plan downgrades to Free, which keeps 3 rooms with Fast models.
Create your first room in seconds. Invite your people. Let the best AI models in the world help your group get things done.
No credit card required.