Brello vs Microsoft Copilot: privacy compared

Summary

Brello 1.0 runs its model on your Android phone, needs no account and keeps chats only on the phone. Microsoft Copilot processes your prompts on Microsoft’s services and keeps your conversations so you can return to them. Microsoft documents two versions of the consumer app. For the updated app, released on 18 August 2026, it says prompts, responses and file contents aren’t used to train foundation models. For the older app, it stores conversations for 18 months by default, may have people review some of them, and trains on them unless you opt out or are excluded. Copilot offers memory, file uploads and voice, which Brello 1.0 lacks. Checked 5 October 2026.

Brello 1.0 processes questions, photos and answers with a language model on the phone, and stores chats in one file in its private app storage, excluded from Android cloud backups and device-to-device transfer.
Microsoft says prompts, responses and file contents in the updated Copilot app, available since 18 August 2026, “aren’t used to train foundation models”.3
For the older Copilot app, Microsoft stores conversation activity for 18 months by default and uses it for AI training unless you opt out or belong to an excluded group, such as signed-out users and users under 18.1
Microsoft’s FAQ for the older Copilot app says some conversations get automated and human review, and that “an opt-out of human review is not available”.1
With web search on, Brello 1.0 sends the search text from the phone straight to a search engine, which sees the phone’s IP address; Copilot generates a short query from your prompt and sends it to Bing.5

Last checked 5 October 20267 Microsoft pagesBrello 1.0, version 1.0.0

Every statement about Copilot quotes or closely paraphrases one of Microsoft’s own pages, numbered under Sources with the date we checked it. Microsoft documents two versions of the consumer Copilot app: an updated app for web, desktop and mobile, available since 18 August 2026, and the older app, whose Privacy FAQ now “applies only to the older version”.1 Where the two differ, we say which one a statement describes. We compare Copilot used with a personal Microsoft account, not Microsoft 365 Copilot with a work or school account. Statements about Brello describe Brello 1.0, a prototype Android app that runs language models entirely on the phone. Our method is set out in the editorial standards, and the AI assistant privacy comparison puts Copilot beside ChatGPT, Gemini, Claude and Perplexity.

At a glance

Brello 1.0 and Microsoft Copilot differ most in where a question is processed, how long it is kept and who may read it.

Question	Brello 1.0	Microsoft Copilot
Where the model runs	On the phone. Questions, photos and answers go only to the on-device runtime.	Your prompt and conversation history pass through input classifiers, then Copilot decides “which language model should respond”.7 Microsoft may process personal data “in your region, in the United States, and in any other jurisdiction” where it, its affiliates or its service providers operate facilities.6
Account required	No. There is no sign-up and no account system.	Updated appMicrosoft’s privacy pages apply “when you sign in with a Microsoft account”.2Older appNot required: the FAQ covers “users who are not signed into Copilot”.1
Offline use after setup	Yes, after a one-time model download of 977 MB to 3.66 GB.	Not stated in Microsoft’s documentation (checked 5 October 2026).
When the web is used	Only when you turn on web search, or approve it for one question. It is off by default.	Copilot “can search the web to improve the quality of its responses”, and the updated app has a Web search toggle.4 The query goes to Bing.5
Where chats are stored	In one file in Brello’s private storage on the phone, excluded from Android cloud backups and device-to-device transfer.	Updated appCopilot “keeps your prior conversations” so you can return to them; no period is stated.4Older app“By default, we store conversation activity for 18 months.”1
Use of chats for training	None. Chats stay on the phone, and there is no Brello server to receive them.	Updated appPrompts, responses and file contents “aren’t used to train foundation models”.3Older appUsed for AI training unless you opt out or are in an excluded group.1
Human review	None. No chat leaves the phone, so no one can review it.	Updated appNot addressed in its privacy pages. Submitted feedback is “reviewed by Microsoft’s operations teams”.7Older appSome conversations get automated and human review, with no opt-out.1
Platforms	Android 8.0 or newer, on 64-bit ARM phones. No iPhone, web or desktop app.	A website and apps “on Windows, Mac, iOS, and Android”.6

Table 1. Brello 1.0 and Microsoft Copilot (consumer app, personal Microsoft account) at a glance. Copilot cells quote or closely paraphrase Microsoft’s pages, checked 5 October 2026; the numbers link to the sources. Brello cells describe Brello 1.0, version 1.0.0; how Brello handles your questions, photos and answers sets out the full data flow.

Where your question is processed

Brello 1.0 processes your question on the phone. Copilot sends it to Microsoft, where it is screened and passed to a language model that Copilot chooses.

In Brello 1.0, the prompt goes only to the on-device runtime, Google’s LiteRT-LM, which runs one of three downloaded models on the phone’s GPU, or on its CPU when the GPU isn’t available: Brello Pro, based on Gemma 4 E4B by Google; Brello Vision, based on Gemma 4 E2B by Google; or Brello Core, based on Qwen3 1.7B by Alibaba. All three are released under Apache 2.0, and Brello isn’t affiliated with or endorsed by Google or Alibaba. Photos are copied into Brello’s private app storage and never uploaded. There is no Brello server, proxy or relay, so there are no Brello logs to keep. The one exception, web search, is covered below.

Microsoft’s Transparency Note for Copilot, dated 18 August 2026, describes the path: “When a user enters a prompt in Copilot, the prompt, conversation history, and the system message are sent through several input classifiers to help filter out harmful or inappropriate content.” Copilot then determines whether the request needs “grounding data from the web and which language model should respond to the request”.7 The Microsoft Privacy Statement says Copilot “will use your prompts, location, language, and related settings to provide helpful responses and improve services”, and that personal data “may be stored and processed in your region, in the United States, and in any other jurisdiction where Microsoft or its affiliates, subsidiaries, or service providers operate facilities”.6

Microsoft’s pages for the updated app apply when you sign in with a personal Microsoft account. Copilot in Microsoft 365 apps, and Copilot used with a work, school or organisational (Microsoft Entra) account, have their own pages and are not compared here.2 For the general difference between cloud and on-device assistants, see on-device AI, explained.

How long conversations are kept

Brello 1.0 keeps chats only on the phone until you delete them. Microsoft keeps Copilot conversations in your history: for 18 months by default in the older app, and for no stated period in the updated app.

Brello 1.0 writes chats, including any “Thought process” text, to a single file, conversations.json, in its private app storage. Android backup is turned off for the app, and its data-extraction rules exclude every storage domain from cloud backup and from device-to-device transfer, so chats are not copied to Google Drive backups or to a new phone. You delete a chat by swiping left on it, or every chat with “Delete all chats” in Settings. Nothing is synced, so if the phone is lost or reset, the chats are gone.

For the older app, Microsoft’s FAQ says: “By default, the conversations you have with Copilot are saved”, and “By default, we store conversation activity for 18 months. You can delete individual conversations or your entire conversation history at any time.” A file you share is “stored securely for a short time (no longer than 18 months) and then automatically deleted”.1

For the updated app, Microsoft says Copilot “keeps your prior conversations with Copilot so you can revisit them or continue them at any time”, and that you can delete a chat from the Chats list.4 The privacy dashboard lets you export or delete all your Copilot activity history.3 None of the pages for the updated app gives a retention period. The Privacy Statement says Microsoft keeps personal data “for as long as necessary to provide the products and services you use”, and for purposes such as improving products and meeting legal obligations, so “actual retention periods can vary significantly”.6

Human review

No one can review a Brello 1.0 chat, because no chat leaves the phone. Microsoft’s FAQ for the older Copilot app says people review some conversations, with no opt-out; its pages for the updated app don’t say.

The FAQ says: “Some Copilot conversations are subject to both automated and human review for product improvement and digital safety purposes.” Review also follows a suspected breach of the Code of Conduct in the Terms of Use, and “an opt-out of human review is not available”. It adds that “trained AI experts may review Copilot conversations to build, evaluate, and improve the accuracy and safety of our AI models”, and that external research organisations can help review Copilot conversation logs. Its advice: “You shouldn’t provide any confidential or sensitive personal data that you would not want Microsoft to use for purposes explained in this FAQ and in the Microsoft Privacy Statement.”1

For the updated app, Microsoft’s privacy pages don’t say whether people review conversations. Its Transparency Note says feedback you submit is “reviewed by Microsoft’s operations teams”.7 Across its products, the Privacy Statement says Microsoft’s processing “involves both automated and manual (human) methods”, and that to build, train and improve its automated systems, such as AI, “we manually review some of the results against the underlying data”.6

Brello 1.0 has no account system, no analytics and no crash reporting, and no Brello server receives your questions. We have nothing for a person to review.

Model training and who is excluded

Brello 1.0 can’t use your chats for training, because they never leave the phone. For Copilot, the answer depends on the app version.

For the updated app, Microsoft says: “Prompts, responses, and your file contents when using the Microsoft Copilot app aren’t used to train foundation models.” Optional feedback may be used to improve Copilot, but Microsoft doesn’t use it to train foundation models either.3 The Privacy Statement still lists other uses: Copilot uses “prompts and related data to provide and improve services, including relevant advertising”, and Microsoft uses conversation data “to monitor performance, troubleshoot and fix bugs and issues, prevent abuse, and to provide and improve Microsoft Copilot”.6

For the older app, the FAQ says: “Except for certain categories of users or users who have opted out, Microsoft uses data from Bing, MSN, Copilot, and interactions with ads on Microsoft for AI training.” That includes “your voice and conversation activity with Copilot, including the images or files you upload”. Microsoft says it doesn’t train Copilot on data from these users:1

users signed in with an organisational Entra ID account;
users of Copilot within Microsoft 365 apps with Personal or Family subscriptions;
users who are not signed in, and signed-in users under 18;
users who have opted out;
users in Brazil, China (excluding Hong Kong), Israel, Nigeria, South Korea and Vietnam.

Opting out “will exclude your future conversations” from training. Before training, Microsoft says it removes “names, phone numbers, device or account identifiers, sensitive personal data, physical addresses, and email addresses”, and it doesn’t train on Microsoft account profile data or email contents.1

Accounts and sign-in

Brello 1.0 has no accounts. Microsoft’s pages for the updated Copilot app describe use with a personal Microsoft account; its FAQ for the older app also covers people who aren’t signed in.

For the updated app, use with a personal Microsoft account is “governed by the Microsoft Services Agreement and the Copilot Terms of Use”.2 The account links Copilot to other Microsoft products: experiences with Bing, Edge and MSN can personalise Copilot, and “your Copilot chats can be used to help personalize your interactions on Bing, Edge, and MSN” unless you turn off “One shared experience”. Without a Microsoft 365 subscription, “you might see advertising in Copilot”; personalised ads “might use your chat history, saved memories, and other Microsoft data you’ve chosen to share”, and can be turned off.4

For the older app, Microsoft doesn’t train on the conversations of people who aren’t signed in, and personalisation “is disabled for unauthenticated users”.1

Brello 1.0 asks for none of this: there is no sign-up, the models download from Hugging Face without an account or token, and the app contains no ads and no analytics.

Offline use

Brello 1.0 works offline after a one-time model download. None of the Microsoft pages we checked describes an offline mode for Copilot.

Brello Core is a 977 MB download, Brello Vision 2.59 GB and Brello Pro 3.66 GB, and Wi-Fi is recommended for it. After that, the assistant works fully offline; only web search, which is optional, needs a connection.

Web search: who sees the query

Both products send a search engine a query built from your question. They differ in who sends it.

Brello 1.0’s web search is off by default. With it off, a question that looks time-sensitive brings up a card titled “Search the web for this?” with two buttons, “Search the web” and “Answer offline”. When Brello searches, the phone sends a cleaned-up search text, sometimes with up to 10 words of the previous question added for context on a follow-up, directly to DuckDuckGo, Bing, Brave Search, Google News or Wikipedia, and then fetches up to four result pages itself. The requests carry Do Not Track and Global Privacy Control headers, and the model that reads the pages and writes the answer still runs on the phone. The search engine and the websites see a normal request, including the phone’s IP address.

Microsoft says Copilot “generates a short query based on your prompt and sends it to Bing”, using “a few words from your prompt or any file you’ve uploaded”; “the full prompt or file is not used as the query unless it’s already very short”. A Sources button under the response shows “the exact query Copilot sent to Bing and the sources it used”. These queries are subject to the Microsoft Services Agreement and the Microsoft Privacy Statement.5

Bing is one of the engines Brello can use, so the difference lies in the sender. With Brello, no company stands between your phone and the search engine, but the engine sees your phone’s IP address. With Copilot, Microsoft receives your whole prompt and sends the query to Bing, under Microsoft’s own terms. How AI assistants handle your data explains these patterns in general terms.

What Copilot offers that Brello 1.0 doesn’t

Copilot has a much wider feature set than Brello 1.0. These are the differences Microsoft’s own pages describe.

Memory across chats. Copilot can remember “key details and preferences from your conversations”, and you can delete what it saves.4 Brello 1.0 carries only the last six messages of the current chat.
Files and documents. You can upload an image or document and ask Copilot to summarise it.1 Brello 1.0 takes text and at most one photo per message, with no files.
Voice. Microsoft lists voice search among Copilot’s features.6 Brello 1.0 has no voice input or output.
History that follows your account. You can return to a conversation or continue it at any time,4 and export your activity history.3 Brello 1.0 has no sync, backup or export.
More places to use it. Copilot runs on the web and on Windows, Mac, iOS and Android.6 Brello 1.0 runs on Android phones and iPhone.
Microsoft 365 and a choice of models. Copilot “is integrated into Word, Excel, PowerPoint, Outlook, Teams, and more”, and you can choose between AI models for different kinds of work, with features varying by subscription.2

Where Brello is weaker

Brello 1.0 is a prototype with small on-device models, and it gives up convenience to keep processing on the phone.

Availability. Brello 1.0 (version 1.0.0, 4 October 2026) is on Google Play and the App Store.
Smaller models. On-device models are far smaller than frontier cloud models: they can be wrong, have a knowledge cutoff and are weaker at long or complex reasoning. Brello’s system prompt asks the model to admit uncertainty, which is no guarantee.
Short memory. A 4,096-token context window; each answer sees only the last six messages, clipped.
Hardware demands. Android 8.0 or newer on a 64-bit ARM phone, 12 GB of RAM recommended for Brello Pro, a 977 MB to 3.66 GB download plus a speed cache of similar size, and up to a minute for a model’s first launch.
Fewer inputs. One photo per message; no files, no voice input or output, and an English-only interface.
No sync, backup or export. If you lose or reset the phone, the chats are gone.
Web search depends on others. Third-party engines can take up to about 14 seconds per attempt or return nothing, and they see your IP address.

Other comparisons

We answer the same questions for four other assistants, each from its provider’s own pages.

Sources, with the dates we checked them

We opened each page ourselves on 5 October 2026. Where a page shows its own date, we give it too.

Microsoft Support. “Privacy FAQ for Microsoft Copilot.” Applies only to the older version of the Copilot app, per Microsoft’s notice of the 18 August 2026 update. support.microsoft.com/en-us/microsoft-copilot/privacy-faq-for-microsoft-copilot. Checked 5 October 2026. Used for: the two app versions, storage for 18 months, training and its exclusions, human review, signed-out use and file uploads in the older app.
Microsoft Support. “Microsoft Copilot for individuals: your data, privacy, and responsible AI.” support.microsoft.com/en-us/privacy/microsoft-copilot/overview. Checked 5 October 2026. Used for: the scope of the updated app’s pages, the terms that govern it, Microsoft 365 integration and the choice of models.
Microsoft Support. “Microsoft Copilot for individuals: your activity history.” support.microsoft.com/en-us/privacy/microsoft-copilot/activity-history. Checked 5 October 2026. Used for: training in the updated app, feedback, and exporting or deleting activity history.
Microsoft Support. “Microsoft Copilot for individuals: your privacy controls and choices.” support.microsoft.com/en-us/privacy/microsoft-copilot/privacy-controls. Checked 5 October 2026. Used for: chat history, memory, shared experiences with Bing, Edge and MSN, the web search toggle and advertising.
Microsoft Support. “How web search works in Microsoft Copilot Chat and agents.” Linked from source 4 as the explanation of web search in Copilot. support.microsoft.com/en-us/microsoft-365-copilot/how-web-search-works-in-microsoft-365-copilot-chat-and-agents. Checked 5 October 2026. Used for: the query sent to Bing, and the terms that cover it.
Microsoft. “Microsoft Privacy Statement.” Last updated September 2026. microsoft.com/en-us/privacy/privacystatement. Checked 5 October 2026. Used for: how Copilot uses prompts and conversation data, human review across Microsoft’s products, where data is processed, retention, voice and platforms.
Microsoft Support. “Transparency Note for Microsoft Copilot (for individuals).” 18 August 2026. support.microsoft.com/en-us/privacy/microsoft-copilot/transparency-note. Checked 5 October 2026. Used for: how a prompt is screened and routed to a model, and review of feedback.

Facts about Brello describe Brello 1.0, version 1.0.0 (build 1), as of 5 October 2026. Product names are trademarks of their owners; Brello isn’t affiliated with them.

Version history

1.05 October 2026First published. All seven Microsoft sources checked on 5 October 2026, covering both the older and the updated Copilot app.