Questions and answers.

A free AI chat app for Windows, in beta. Quick questions get a quick answer. Big ones get a short answer at once, then a full one that several AIs research, write and check together, with charts, checklists and calculators where they help. You bring your own OpenRouter key, or sign in to OpenRouter in one click, and use any model you like, free or paid. It also has what you'd expect: side-by-side model compare, a prompt library, memory, web search with sources, files in and out, voice and spending limits. More is on the way; see the roadmap.

No catch. Chat is free and stays free, with no subscription, trial, account or message limit from us. You pay your model provider for paid models, at their prices, or nothing on free models. Later there'll be optional paid add-ons like Mosaics, for people who want them. What's in Chat now stays in Chat.

Because a chat app gets good by being used by lots of people who say what's wrong with it. Chat is also what everything else in Mosaik is built on. Mosaik will pay its way later with optional add-ons, never with ads or your data.

It works, and it's used every day, but it's early. Some things will be rough, some will change, and plenty is still to come. Updates install themselves, and Report a problem in the app goes straight to the developer.

A big question gets a short answer straight away and a full one built by several AIs at once, so you never wait on a blank page. You're not tied to one company's models, and you pay per use instead of a monthly subscription. You also get more say: your instructions override Mosaik's, every setting is there to change, a side question doesn't clutter the chat, and you see what each answer cost. And your chats stay on your computer.

You get a short answer in a few seconds: two to four sentences with only what's certain. Then an outline appears, and each part is researched, written and checked by its own AI, all at the same time, up to eight for a report. Parts appear as they pass their check, and nothing you've already read changes. Small talk and quick facts still get one quick reply. Turn it off in Settings, or for one message from the send arrow.

Yes. Ask either for your data export, then choose the file in Mosaik's Import chats. Every chat comes over with its dates and every answer version, and the file is read on your computer. See Importing.

Select words in any message and press Ctrl Shift K. A small window opens next to them where you can ask about the selection. The answer knows the conversation, and nothing is added to the chat.

Almost any: pictures, PDFs, Office and OpenDocument files, audio, video, archives, code and text. Each goes to the model in a form it can take, and when it can't take one at all, a quick model describes or transcribes it first. Ask for a spreadsheet, a slide deck, a document, a picture or a ZIP and it arrives as a file you can open and save. See Attachments.

No. There's nothing to sign up for with us. For the models, a free OpenRouter account is the easiest start, and the setup guide signs you in with one click. Your own key or local models work too.

The app runs on Windows 10 and 11, 64-bit. Linux is next, a mobile app is planned, and macOS may follow. Mosaik in your browser is coming soon too.

It's coming soon: a lighter Mosaik for any computer or phone, with nothing to install. The roadmap shows what comes next.

One independent developer in Hungary. There are no ads, and your data isn't the business. See About.

Nothing. There's no subscription, trial or account, and no limit on how much you use it.

Paid models are billed separately by OpenRouter, by use and at their prices. Free models cost nothing. Mosaics will be an optional paid add-on when it arrives.

All of Chat, including every update: Dynamic output, smart elements, Smart mode, any model, compare, the prompt library, memory, quick-ask, web search, files, voice, styled answers, saved setups, spending limits and settings changed from any chat. Only future add-ons like Mosaics will cost money.

One key reaches hundreds of models from OpenAI, Anthropic, Google, Meta, DeepSeek, Mistral and others, at the providers' own prices. You're never locked to one company, and you can switch model mid-conversation. The docs show how to connect.

No. Mosaik isn't part of OpenRouter or affiliated with it. It uses OpenRouter to reach the models, and OpenRouter bills you directly for any paid ones.

Yes. Keep Cost at Free, where new accounts start, or turn off paid models in Settings › Spending, and only free models run, with no card needed. OpenRouter allows 50 free-model requests a day, or 1,000 a day once you've bought $10 of credit, once. Free models are sometimes busy or unavailable, and Mosaik works best with frontier paid models, which cost a cent or two a reply.

It depends on the model and the length. With Cost at A little, a short answer without web search usually costs a fraction of a cent, and at Free it costs nothing. Every answer shows its price, so you'll see for yourself, and a $10 monthly limit is on from the start.

Settings › Spending sets a daily and a monthly limit and can switch paid models off. A request that would go over a limit is never sent. See Costs and limits.

Yes, that's much of the point. Set the model, your instructions, the temperature and the answer length for everything, then change any of them for one chat. Your instructions win over Mosaik's own guidance.

Through OpenRouter, yes. OpenRouter lets you add your OpenAI, Anthropic or other provider keys to your OpenRouter account, and Mosaik uses them from there.

Not yet. Models running on your own computer, with Ollama or LM Studio, are on the roadmap for later. For now every model comes through OpenRouter, free ones included.

On your computer, in a database in %APPDATA%\Mosaik\Mosaik. We never receive them. Backing up is copying that folder.

Yes, Mosaik installs on as many computers as you like. Each keeps its own chats for now. Mosaik Cloud, coming soon, will keep your chats and settings the same on all of them. It will be a small paid add-on, because it runs on servers that cost money every month. Chat itself stays free.

In Windows Credential Manager. Signing in always keeps it there; a key you paste is kept there if you choose to remember it, and otherwise only in memory until Mosaik closes. It's never written to the database or the log, and only ever sent to OpenRouter.

Your messages go to OpenRouter and the model you picked. Web searches go to the search engines that answer them, and pages are fetched from their sites. The update check tells mosaikchat.com your Mosaik and Windows versions. A problem report, feedback or a feature suggestion goes only if you send it. The privacy notice has the full list.

No. The app has no analytics, telemetry or usage statistics, and this site runs no analytics scripts. The site counts two things as one total a day: downloads, and the app's checks for a new version. Nothing about who made them is kept. See Privacy.

That depends on the provider. OpenRouter's privacy settings let you exclude providers that train on or log your prompts. Their policies apply to what you send them.

The installer isn't code-signed yet, so SmartScreen shows “Windows protected your PC”. Click More info, then Run anyway. The Download page has the file's SHA-256 if you want to check it. We plan to sign it.

No. Mosaik installs for you alone, in your own user folder.

On its own, by default: it downloads a new version in the background and installs it when you close Mosaik. It can ask first instead, or not check at all. See Updates and your data.

Windows Settings › Apps › Installed apps. Your chats stay until you delete them; Uninstalling says where they are.

Try Troubleshooting, send a report from the app with Report a problem (the speech-bubble button at the top of the sidebar), or ask in the community.

Mosaik in your browser is coming soon, then a Linux version, with more in Chat guided by what people ask for. Further off: a mobile app and Mosaics. The roadmap has the details.

Yes, it's planned, with the same idea: your key, your models. There's no date yet.

Mosaics is the part of Mosaik for code, writing, art and research. You can use each on its own, and a mosaic is a project that brings them together: a book, an app, a small business, a hobby. You talk to one AI, the lead, which plans the work, hands parts to the right tools and checks with you before anything is final. See Mosaics.

When it's ready. We'd rather not guess a date. Leave your email and we'll tell you when it's out.

It'll be an optional paid add-on, and we'll say how much before it's out. Chat stays free either way.

It edits your files and runs commands in your project, so it isn't sandboxed from them. The safety nets are rules for commands (reading and tests run, installs and deletions ask first, destructive commands are refused), a checkpoint for every turn that you can undo, and plans that wait for your approval.

Send you Mosaik news: big releases, the Linux and mobile apps, and Mosaics. A few emails a year, nothing else. We don't share it, and you can ask us to delete it at any time.

Use the unsubscribe link in any of our emails, or write to us from the address you signed up with (see Contact) and we'll remove it.