AI notes apps where you bring your own key and switch models

An AI notes app where you bring your own key lets you connect the AI account you already have, switch models when a better or cheaper one comes along, and keep every note and task where it is. Barside works this way. It's a free desktop app for Windows, Linux and Mac, and it has no AI model of its own. You connect Claude, ChatGPT, Gemini or OpenRouter in Settings → AI, pick a model, and switch to another connected company with one click. Your library never lives with the AI company, so switching only changes which AI answers your requests.

This guide covers how bring-your-own-key (BYOK) works in desktop notes and assistant apps, what it costs next to a subscription, what stays put when you change providers, and how support differs on Windows, Mac and Linux. It ends with the exact steps to connect an account in Barside.

How an AI notes app with your own key lets you switch models

In an AI notes app where you bring your own key and switch models, the app and the model are kept apart. Most AI notes apps bundle a model into a monthly plan. A BYOK app separates the two: the app supplies the tools, such as editing notes, adding tasks or searching your library, and the AI company supplies the thinking, billed to your own account through its API.

In Barside, every request follows the same path. You type or say what you need, and Barside sends it to the AI you connected along with a list of its tools. The AI picks a tool, Barside runs it on your computer, and the loop continues for up to 40 steps. The AI assistant for your computer and notes shows each step in an activity log, and anything that rewrites text or touches another app waits for your approval first.

That design has three consequences:

• The AI company sees only what each request needs. It receives your request, tool results, the memories the assistant needs and matching excerpts from your notes, without your whole library.
• The key stays with you. Barside saves it encrypted on your computer and sends it only to its own company, with no Barside server in between for work on your computer.
• Switching is cheap. The notes, tasks and history belong to Barside, so a new provider only changes where the next request goes.

What stays put when you switch AI providers?

An AI assistant app with multiple AI accounts, where you can switch providers and keep your notes and tasks persistent, comes down to where those notes and tasks are stored. In Barside, they're stored in Barside's data folder on your computer. You can connect more than one company in Settings → AI and click the one you want to use. The line under the assistant's name always shows the AI and the model in use, so you know which one will answer.

When you switch, all of this stays where it was:

• Notes, workspaces and drawings. They're files in your library, saved as you type, with no account needed.
• Tasks and reminders. Every checklist item and reminder lives in a note, so the task board looks the same whichever AI you use.
• Assistant conversations and Undo. Conversations are kept by Barside, and the Undo buttons still work after a restart.
• Agents and saved workflows. Their settings, instructions and the notes they wrote stay in your library. The next run uses whichever AI is connected.
• Your choices about privacy. Workspaces you untick in Library & briefing → Sources stay out of AI requests no matter which company you pick.

Plan for one difference: features depend on what each company offers. Web search in the assistant works with Claude, ChatGPT and OpenRouter, and Gemini has no web search in Barside. For screen understanding, choose a model that can see images.

A couple of examples show how people use this. Maya, a freelance copywriter, drafts in Claude and keeps OpenRouter connected so she can try a new model on the same client notes without moving anything. Dev, a graduate student, starts with Gemini for everyday summaries and switches to ChatGPT on days he needs the assistant to search the web for sources. Neither of them exports or re-imports a single note.

How to connect an AI account in Barside

1. Download Barside for Windows, Linux or Mac, and open it.
2. Press Ctrl+Shift+A, or choose Assistant in the sidebar. The first time, it shows Connect an AI to start, with one button per company. The same buttons are in Settings → AI.
3. For Claude, ChatGPT or Gemini, Barside opens that company's key page in your browser. Make a new key and copy it. Barside picks it up from the clipboard, checks it and saves it encrypted.
4. For OpenRouter, sign in and press Authorize. There's no key to copy.
5. Choose a model under the buttons. Claude and OpenRouter start with Claude Opus 5, ChatGPT with the newest balanced GPT model on your account, and Gemini with the newest Gemini Flash.
6. Connect a second company the same way if you want a fallback or a model to compare.
7. To switch later, open Settings → AI and click another connected company.

If you already pay for a Claude or ChatGPT plan, choose My plan instead. Barside then runs Claude Code or Codex on your computer, signed in with your plan, so you skip API billing.

Does your own key cost less than a subscription?

With an API key, you pay the AI company for what you use, request by request. Light or uneven use often costs little, while long research sessions or agents that run every day add up. A subscription app charges the same each month whether you use the AI or not, and it usually picks the model for you. Our guide to AI note-taking app pricing in 2026 works through both, and AI research assistant pricing compares subscriptions with paying for the API.

Barside charges nothing for AI. The app is free, agents included, and Barside Plus (US$20 a month or US$200 a year) adds cloud sync, encrypted cloud backup and cloud agents, with no AI credits inside it.

To cap API spending, open Settings → AI and turn on Limit what Barside's AI spends under AI spending limit. Set an amount from US$0.50 to US$10,000 for a day, a week (from Monday) or a month.

• Barside estimates each answer from the company's list prices for your model. OpenRouter reports the exact cost, so Barside uses that.
• At 80%, you get a notification and a banner in the assistant and Library.
• At the limit, the assistant, agents, Ask library, Quick AI and the Space helper stop sending requests until you raise the limit, turn it off or the count starts again.
• Each computer counts its own use, and cloud agents aren't counted, so set a limit on your AI account too.

How Windows, Mac and Linux support compares

Most lists of BYOK apps skip the operating system, which matters if you split your week between machines. The table compares three desktop tools, with other companies' facts as of September 2026.

Raycast is a strong keyboard launcher with a large extension store. Its bring-your-own-key manual explains that requests with Anthropic, Google or OpenAI keys go through Raycast's servers, while OpenRouter requests go straight to OpenRouter. BYOK needs a paid plan, with Pro at US$10 a month as of September 2026 on Raycast pricing, and its FAQ says there are no plans for Linux. Notion is excellent for shared databases and team wikis, and its AI comes with its plans; its desktop app is for Mac and Windows. For a launcher-focused comparison, read the Raycast alternative for Windows, and for a notes-focused one, the Obsidian alternative with the AI you choose.

Which desktop AI app works on Linux with your own key?

If you're looking for the best desktop AI app for Linux where you bring your own key, start by checking whether the app runs natively on Linux at all. Barside does. It installs as an AppImage or a .deb package and uses the same Settings → AI connection on Linux as on Windows, and Barside for Mac uses it too. The assistant, AI search, agents and Quick AI all run on your key.

A few things work differently on Linux, and it helps to know them before you start:

• Other apps. The assistant can list, focus and minimize windows and press keys, but it can't read the controls inside other apps. On Linux, it does best with commands about your notes, tasks and Barside itself.
• Hotkeys on Wayland. Global hotkeys work while an X11 app is active, and Barside gives you a command to add as a shortcut in your desktop's keyboard settings.
• Voice. Hey Barside works on Linux with Barside's own speech engine and needs no extra speech pack.

Priya, a backend developer, uses Linux at home and Windows at work, and colleagues on a Mac use Barside for Mac. She keeps one Barside library per machine, or syncs them with cloud sync between computers in Barside Plus. The same key and the same model choice work on both of her computers.

Can agents keep working when you switch AI?

In AI agent desktop apps, switching LLMs with your own key shouldn't touch your notes, and in Barside it doesn't. AI agents that ask before they act run on the AI you connected, so a Morning briefing agent written for Claude keeps running if you move to OpenRouter. Its instructions, schedule and past notes stay in Agents & approvals, and anything it proposes still waits in the Inbox for Approve.

With cloud agents in Barside Plus, your key goes to Barside's server, sealed, and is used only to run your scheduled agents. If you change the AI or its key on the computer that sent it, that computer sends the new one within about two minutes. Remove my AI key from Barside deletes it from the server at any time.

It works in the other direction too, so you can use Barside from another AI app. Through AI connections, Claude Desktop, ChatGPT and other apps can read the workspaces you choose for each connection.

Where do your notes and your key live?

Your library lives in Barside's data folder, with no account required. When you use the assistant, your request, tool results, needed memories and matching excerpts go to the AI company you connected, and that company's data policy applies. Your voice is turned into text on your computer first. Read the AI you connect and your data, and if you handle client work, AI note apps and client confidentiality.

Cloud sync isn't end-to-end encrypted. Barside's server can read synced notes, which is how cloud agents can run. Cloud backup works differently, because only your recovery key opens it. See local-first storage, backups and sync and the wider list of local-first apps.

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