Privacy and security

Nanobrowser runs in your browser. There is no account, and no Nanobrowser server receives your chats or pages. Your chats, files and settings are stored in your browser. To do a task, it sends pages to the model you picked.

What goes to my model provider?

Nanobrowser sends these straight from your browser to the model provider you set up, such as Anthropic, OpenAI, Google or OpenRouter:

• Your messages, your custom instructions and the files you attach.
• Text you quote from a page with Ask Nanobrowser about this.
• The content of the tabs the agent works in. This can include personal details shown on those pages, such as names, emails or orders.
• Screenshots of those tabs, for models that can see images.

What the provider does with it is up to its own privacy policy. OpenRouter passes your requests on to the company that serves the model you pick.

If you use a local model, such as Ollama or LM Studio, this data stays on your computer.

Some things are kept from the model:

• Your logins and cookies. They never leave your browser through Nanobrowser.
• The values of password, card number and one-time code fields, when Nanobrowser recognizes them. It may not recognize every one.

What you type in the chat always goes to the model. If a message looks like a card number, Nanobrowser warns you before it sends it.

What goes to my voice provider?

Only if you use voice input. The audio of each recording goes to the voice model you chose, from OpenAI or Google. Recordings aren’t kept by Nanobrowser. That provider’s own privacy policy applies.

Where do my API keys go?

• Keys are stored in your browser.
• Each key is sent only to its own provider.
• Keys are never in exports and never written to logs.

What does Nanobrowser send to us?

There are two switches in Settings → Data → Privacy. Both are on by default.

Switch	What it sends
Anonymous daily count	A short note at most once a day, on days you use Nanobrowser. It says the version, the browser, Nanobrowser’s display language, the week you installed it, whether it’s a new install, whether this is your first use this week and this month, whether you have a model set up, and whether you ran a task that day.
Help improve Nanobrowser	Usage totals for a past day, at most once a day. For example: how many tasks ran and how they ended, which tools ran, which errors happened (as error codes, with no text), which kind of provider and mode you used, which features you used, how many site rules you have, and how often approval cards were shown, allowed or denied.

For the full list, see the privacy policy.

What this data never includes:

• Your pages, the sites you visit, or your messages.
• Your files, your keys, or the text of your settings.
• Any ID that could tell your browser apart. The daily count can’t be linked from one day to the next, and the totals name no one.

It goes to PostHog, a product analytics service, in the United States. Nanobrowser asks PostHog not to store your IP address, not to work out your location, and not to make a profile of you. The data is kept for one year.

How do I turn it off?

• Open Settings → Data and turn off Anonymous daily count, Help improve Nanobrowser, or both.
• You can also turn off Help improve Nanobrowser on the welcome page when you first set up.

When you turn a switch off, anything counted and not yet sent is deleted at once.

If you turned off Help improve Nanobrowser in the earlier version (v0.2), both switches start off.

When you remove Nanobrowser, your browser opens a short Google Form that asks why. It’s optional, and Nanobrowser fills in nothing in it. Google asks you to sign in so each person answers once, but the form doesn’t record who you are.

How do I see or delete my data?

Open Settings → Data:

• Storage used shows how much space Nanobrowser’s data takes in this browser.
• Delete everything deletes all chats (including old v0.2 chats), attached files and task records, your shortcuts, your site rules, your settings, and your models with their API keys. Running tasks stop first. This can’t be undone. Your two Privacy switches stay as they are.

To delete one conversation, use Recent tasks in the side panel. To keep a copy of one, use Export as Markdown there.

Removing the extension also deletes all of its data in your browser.

How does Nanobrowser handle prompt injection?

• The agent is told to treat text on a page as data, never as orders. Only your messages are orders.
• Your mode and site rules are kept by the extension. The model can’t change them, and neither can a page.
• Payments, passwords, codes and access grants are always your steps, in every mode.
• The agent works only in its own tabs. It can’t run code in a page, read files on your computer, or upload a file you didn’t attach.
• Every step it takes is listed in the chat.

No protection is perfect. A clever page can still fool the model. For example, a fooled agent could read something on one site and carry it to another, by typing it or by opening an address. Opening pages and typing don’t ask, in any mode.

How can I use Nanobrowser safely?

• Start with sites you know. Try it first on websites you use often. Watch what it does.
• Use a separate profile. Make a separate Chrome profile for Nanobrowser, without your sensitive data or logins.
• Skip risky tasks. Avoid payments, private data and websites you don’t trust.
• Keep Ask mode unless you trust the task and the sites.
• Set important sites to Ask or Block, such as your bank or your email. See site rules.
• Read approval cards before you click Allow. Check the site it names.
• Click Stop at any time to take over.

Which Chrome permissions does Nanobrowser need?

These are permissions for the extension itself. They are not the same as the agent’s Ask and Auto mode.

Always needed

Permission	Why
Access to all sites (<all_urls>)	So the agent can work on any site you send it to.
debugger	To read pages, click and type. While the agent works, Chrome shows a bar: 'Nanobrowser' started debugging this browser.
tabs	To open, switch and close the tabs of a task.
sidePanel	To show the side panel.
storage and unlimitedStorage	To keep your chats, files and settings in your browser. Chats with images can get large.
webNavigation	To notice when a page opens a new tab, and to redraw the page border after a page loads.
alarms	To check on a running task every 30 seconds, so it carries on if Chrome puts the extension to sleep.
offscreen	To prepare a file before it’s saved to your Downloads folder.
contextMenus	To add Ask Nanobrowser about this to the right-click menu when you select text.
scripting	To draw the glowing border around the page the agent works on. To turn it off, use Show page border in Settings → General.

Optional

Four permissions are optional. Nanobrowser works without them, with less. Allow them in Settings → Permissions → Additional browser permissions, or on the welcome page. One click asks for all four.

Permission	Without it
tabGroups	The agent’s tabs are still grouped, but the group has no name and the default color, so it doesn’t show ● or ! for the task’s state.
notifications	No system notification when a task is done or needs you. When the side panel is closed, the badge on the toolbar icon is the only sign.
downloads	The agent can’t save files. When it tries, the Save this file? card asks Chrome for it when you click Save or Save as….
downloads.open	A saved file has no Open or Show in folder button.

Voice input also needs the microphone. Allow it in Settings → Permissions → Microphone.

How do I report a security problem?

Please don’t post it in public issues, pull requests or discussions. Report it through a GitHub Security Advisory, so it can be fixed before it’s made public.