Beyond instant messaging applications, it's important to remember that other applications on your smartphone can exploit your data for commercial purposes. Fortunately, there are open-source alternatives that respect your privacy. That's what I'd like to introduce to you in this chapter.

I won't go back over the alternatives for browsers and instant messengers here, as we've already covered them in detail in previous chapters.

Email remains an essential communication tool, but the most popular applications, such as Gmail or Outlook, pose a number of privacy issues. These services often analyze your messages, store metadata and participate in the creation of advertising profiles.

Alternatives:

FairEmail is a comprehensive, security-oriented Android application. It supports all IMAP/SMTP providers, enables message encryption via OpenPGP, blocks remote images (used as trackers), and uses no third-party services. It gives you fine-grained control over connections, notifications and synchronization behavior.

K-9 Mail is an open-source Android mail client, recently integrated into Mozilla's Thunderbird ecosystem. It supports multiple accounts, PGP encryption via OpenKeychain, and works without an intermediate server.

Thunderbird Mobile is the mobile version of the popular open-source e-mail client developed by the Mozilla Foundation. True to the project's philosophy, the application emphasizes confidentiality, code transparency and the absence of intrusive telemetry. Thunderbird Mobile is based on the K-9 Mail application, of which it is the official successor on Android. It features advanced management of IMAP and POP accounts, e-mail encryption (via OpenPGP), and a simple, efficient interface.

Tuta (formerly "Tutanota") offers a complete end-to-end encrypted email solution, but its mobile client only supports Tuta accounts. It does not work with other providers. interface is modern and uncluttered, and registration requires no personal data.

Proton Mail is a secure Swiss-based messaging service offering native end-to-end encryption between Proton users. The mobile application is open-source, ad-free and collects no personal data upon registration. Proton Mail only supports Proton accounts, but allows encrypted sending even to external addresses via a password.

An email system is based on 2 distinct components: The email provider (such as Gmail, Tuta or Proton Mail), which handles receiving, sending and storing messages via servers; and the email client, which is the application used to view and write your emails (such as Gmail the application, Outlook, K-9 Mail or Thunderbird). The client can connect to different providers via standard protocols such as IMAP or SMTP.

It is therefore possible to use a privacy-friendly open-source client while initially maintaining an account with a more traditional provider. Some applications, such as Gmail, Proton Mail or Tuta, offer email clients that also act as a messaging provider, and thus offer a complete solution integrating both the interface reading and sending/receiving email service.

Here are a few suggestions, when you're choosing your email provider:

Most classic mapping applications, such as Google Maps, Waze or Citymapper, collect a great deal of personal data. They record your movements, searches and habits, and use them for commercial purposes.

Alternatives:

Organic Maps is a free offline navigation application. It is based on data from OpenStreetMap, an open, collaborative database. You download the maps of the regions you're interested in, then navigate without a network.

It contains no advertising, tracking or data collection. The app is particularly suited to journeys on foot, by bike or car, with interface simple, fast and distraction-free.

OsmAnd (OpenStreetMap Automated Navigation Directions) is another comprehensive open-source mapping application. It offers offline GPS navigation, detailed maps (including trails, bike paths and landforms), and extensive customization.

You can activate different layers (pedestrian zones, public transport, etc.), define speed alerts or integrate specialized maps such as those for hiking or nautical routes.

The free version is already very rich, and the paid version allows you to unlock even more features and support the project.

Classic office tools such as Google Docs or Microsoft Office are very practical, but pose serious confidentiality problems. Documents are stored on their servers, analyzed, and sometimes used for marketing purposes or to train AI models.

Alternatives:

Collabora Office is a mobile version of LibreOffice, designed for Android and iOS smartphones and tablets. It lets you create, edit and share office documents without ever leaving your device or personal cloud.

The application supports collaborative editing when connected to a Nextcloud instance with the Collabora Online extension. This makes it possible to reproduce a Google Docs-like experience, but by hosting your files yourself.

ONLYOFFICE is an open-source office suite. It lets you open and edit Word, Excel and PowerPoint documents directly on your mobile, even locally. You can also connect it to various cloud services for automatic synchronization, such as Nextcloud.

Services such as Google Drive or Dropbox store your files on remote servers belonging to private companies. Your data can then be scanned and used for advertising or statistical purposes. What's more, you need an Internet connection and a third-party account to access them.

Alternatives:

Nextcloud is an open-source personal cloud solution that you can host yourself or use via a trusted provider. It lets you synchronize, share and edit your files from your smartphone, while retaining total control over their storage.

On Android, you can install the official Nextcloud mobile app to access your personal cloud from anywhere. You can also add functions such as photo management, office, calendar and messaging.

Material Files is an open-source file manager that's light and uncluttered. It lets you browse, move, copy or delete files locally on your Android device.

The application contains no ads or trackers, and requires no abusive permissions. It's an interesting alternative to the Google-supplied file explorer, often integrated into other proprietary cloud services.

Many people use applications like Google Calendar or Outlook Calendar to manage their appointments. Yet these services are connected to centralized online accounts that collect data on your habits, meeting locations and interactions.

Alternatives:

Etar is a simple, efficient and completely open-source calendar. It can run locally, but also allows synchronization via CalDAV, a standard protocol for synchronizing calendars with privacy-friendly services (such as Nextcloud or EteSync).

This application is part of the "Simple Mobile Tools" suite. It requires no account or network access, making it ideal for completely offline use. You can add events, set reminders and organize views by day, week or month. Like the rest of the suite, Simple Calendar is ad-free, tracker-free and 100% open-source.

Tuta Calendar, developed by the team behind Tuta Mail, is a fully end-to-end encrypted calendar designed to keep your events confidential. It works on Android, iOS and via a web client. Even the titles, descriptions and metadata of your events are encrypted, ensuring that no third party, including Tuta, can access your data.

Proton Calendar also offers native end-to-end encryption for your events and their metadata. It is accessible on mobile (Android, iOS) and via a web client, with a clear and intuitive interface. The service enables the creation of multiple calendars, import/export of events and sharing options. The web client is open-source, but the mobile applications are not yet fully open-source.

Applications like Evernote, Google Keep or OneNote are used to capture ideas, organize tasks or save lists. However, they all rely on proprietary online services, which centralize your data on their servers and often analyze your content for commercial purposes.

Alternatives:

Quillpad is a lightweight application designed specifically for Markdown note-taking. It lets you optionally encrypt your notes, organize your content by tags and colors, and add reminders. Everything works without an account or connection, and data remains stored on your device. They can also be saved encrypted on pCloud.

Joplin is a more comprehensive solution, offering synchronization of encrypted notes via compatible services such as Nextcloud, Dropbox or WebDAV. You can manage simple or structured notes (in Markdown), classify your documents, and even import file attachments.

Its interface is a little more complex than QuillNote's, but it's still perfectly usable on mobile, and suitable for both personal and professional use.

Many users let their browsers store their passwords via solutions such as Google Password Manager. While convenient, this type of centralized management doesn't offer user-controlled end-to-end encryption, and exposes your credentials to risk should your Google account be compromised. For a more secure and sovereign management of your passwords, several open-source alternatives are available.

Alternatives:

Bitwarden is one of the most comprehensive open-source password managers available. It encrypts all your credentials locally, lets you generate strong passwords, and offers encrypted synchronization between devices.

You can use Bitwarden's servers, or self-host it if you like for total control. Its interface mobile is clear and fluid, with seamless integration into the Android or iOS system.

KeePass is a historical password manager based on encrypted local files. On mobile, KeePassDX is an excellent Android implementation, compatible with all KeePass databases. It works offline, without a cloud, making it a good solution for those who want to keep their data 100% local.

There's also KeePassium for iOS, a well-integrated application in the Apple ecosystem, compatible with the KeePass format and open-source. Another iOS alternative for a KeePass client is Strongbox, but this software has not been open-source for several years.

Launched by the Proton team (known for Proton Mail and Proton Drive, among others), Proton Pass combines ease of use, end-to-end encryption and privacy-friendly Swiss infrastructure. The mobile application is intuitive, lets you add secure notes, and supports auto-completion. It's an excellent alternative for those who want a turnkey solution, without worrying about technical management.

VPNs (Virtual Private Network) enable you to encrypt your Internet traffic and route it through a remote intermediary server. This masks your IP address, secures your connections on public networks (airport Wi-Fi, cafes...) and protects you against certain forms of surveillance.

However, not all VPNs are created equal. Popular services like NordVPN or ExpressVPN work well, but their approach remains commercial, with a model based on user tracking for marketing optimization. They also require account creation and often collect more data than they let on.

Alternatives:

Mullvad is one of the best VPNs in terms of privacy protection. It requires no email or password: Your account is linked to a simple random number. Payment can be made in bitcoins or cash. The mobile client is open-source, easy to use and powerful. Mullvad keeps no logs, does not track its users, and regularly publishes independent security audits.

IVPN is another excellent privacy-focused alternative. It offers a simple and efficient mobile interface, no log collection, and allows anonymous registration. You can also pay in bitcoins. The application incorporates a firewall blocking all non-VPN traffic, which can be very useful on a smartphone. The clients are open-source.

Developed by the Proton team, this VPN offers a free, ad-free plan. Proton VPN is based in Switzerland, subject to strict privacy laws, and publishes regular audits. Its clients are also open-source.

Two-factor authentication (2FA) is an additional layer of security on top of your password. It often relies on a one-time code generated every 30 seconds by an authentication application. This code is based on a secret shared between your device and the online service, according to the TOTP (Time-based One-Time Password) protocol. The best-known application is Google Authenticator, but it's not open-source and makes you dependent on the Google ecosystem.

Alternatives:

Aegis is a comprehensive open-source application. It encrypts your 2FA database with a password, offers exportable backups (also encrypted), and lets you sort your accounts by directory. The interface is clear, modern and easy to restore on a new device, as long as you have the backup file and associated password.

Ente Auth is a modern, open-source, multi-platform solution with end-to-end encrypted backups. It enables you to synchronize your 2FA codes securely on mobile, desktop and web. You can also use it offline, without cloud backup or account creation.

Ente AuthAn open-source, end-to-end encrypted 2FA authenticator

Ente Auth offers many additional features: Organization by tags, customized icons for each service, notes, favorites, integrated search, secure team code sharing.

Authy offers 2FA synchronization across multiple devices, which can be handy, but the application is not open-source and requires a phone number for registration. For beginners, however, it is more complete than Google Authenticator, thanks in particular to its cloud backup function.

Proton AuthenticatorHow can I use Proton Authenticator to secure my accounts with 2FA?

If you'd like to find out more about password managers, 2FA authentication and VPNs, I recommend you read the dedicated chapters in the SCU-101 course:

Classic weather applications like AccuWeather or Météo France often collect personal data, including your precise location, usage habits and sometimes even device identifiers, for commercial or advertising purposes. These services also rely on centralized proprietary APIs, limiting your control over what data is displayed or transmitted.

Alternatives:

Geometric Weather offers detailed forecasts and customizable widgets, all without advertising or intrusive data collection. Its code is open-source. The application supports several weather providers.

Prognoza is a minimalist application that gets straight to the point: Displaying current weather and forecasts. It offers several widgets. Prognoza is ad-free, tracker-free and requires no unnecessary authorization.

Simple weather application, based on OpenWeatherMap, open-source, configurable, with widgets.

More generally, on weather applications, it's better to manually configure the locations you're interested in than to activate automatic geolocation.

Popular platforms like Spotify or YouTube offer a seamless user experience, but at the cost of a significant compromise on privacy. These services constantly collect behavioral data: Viewing or listening history, time spent, content preferences, device used. This information is often used for profiling or targeting purposes.

Alternatives:

LibreTube is an Android application that lets you watch YouTube videos without Google tracking you. All requests are redirected via a Piped proxy server, which anonymizes access to videos. Its interface is modern, fast and ad-free. The application requires no Google account, and lets you anonymously subscribe to channels or create local playlists.

NewPipe is another alternative YouTube client. Lightweight, ad-free, tracker-free and entirely open-source, it lets you view, download or listen to videos from YouTube (and other platforms such as SoundCloud or PeerTube) in the background. No connection to Google is required. NewPipe works completely independently of the official YouTube application, and does not require any Google service to operate.

The popular VLC media player is also available on Android. It supports a wide range of audio and video formats, and lets you play files locally or over a network, all without advertising or data collection. It's an excellent solution for managing your own multimedia library locally, without connection to a third-party service.

Funkwhale is a decentralized platform for sharing and listening to music, with compatible clients.

Virtual keyboards such as Google's Gboard or Microsoft's SwiftKey are ubiquitous on smartphones. However, they pose major privacy risks: Every character typed can theoretically be recorded, analyzed or transmitted to remote servers. Even if these companies claim to anonymize data, collection is still possible.

Alternatives:

OpenBoard is a minimalist, open-source Android keyboard based on the AOSP (Android open-source Project) keyboard. It contains no proprietary components or trackers, and never communicates with remote servers. Autocorrection, predictive typing and a personal dictionary work locally only.

FlorisBoard offers a more modern, modular approach. Also open-source, it integrates advanced functions such as gesture input, personalized key layout and multilingual management. All data processing is done locally, without connection to external servers. FlorisBoard is still under development, but is already fully usable on a daily basis for those who want a powerful keyboard without sacrificing their privacy.

The Google Calculator application, while effective, is still a Google product and comes with the usual risks associated with data collection and dependence on a centralized ecosystem.

Alternatives:

OpenCalc is a fast and easy-to-use open-source calculator, perfectly suited to everyday needs. It collects no data and works entirely offline, without advertising or dependence on any external service.

The Google Play Store is the default source of applications on the majority of Android smartphones. However, it is deeply integrated with Google services and involves systematic data collection, even during simple searches or updates.

Alternatives:

F-Droid is an exclusively open-source application catalog. All available software is freely auditable and downloadable, without advertising, tracking or dependence on Google services. The F-Droid application itself requires no user account.

Aurora Store lets you access the Google Play Store catalog anonymously, without a Google account. It's a free client that interacts directly with Google's servers, while masking your identity via a generic account. It's a valuable solution for continuing to use certain necessary proprietary: Applications, while avoiding Google Play telemetry.

The Google News application, while practical and personalized, relies on a systematic analysis of your interests, browsing history and reading habits to refine its recommendations. This involves extensive collection of personal data, often used for advertising purposes.

Alternatives:

The News application, developed by Bubelov, offers a radically different approach. It's a minimalist RSS reader, designed to consult news without trackers, advertising or opaque recommendation algorithms. You can manually select your sources (press, blogs, podcasts, independent media, etc.), guaranteeing a neutral, private reading experience. The design is uncluttered, feeds are updated automatically, and no data is passed on to third parties.

Google Contacts, like many default applications on Android, permanently synchronizes your address books with Google's servers. This means that all your contacts' information (names, numbers, e-mails, sometimes postal addresses or photos) is stored online and associated with your account. This centralization facilitates backup and synchronization, but raises major privacy issues.

Alternatives:

Connect You is a lightweight, uncluttered open-source alternative, designed for those who want to manage their contacts locally, without data collection or forced synchronization with a third-party cloud. It offers an intuitive interface, makes it easy to sort, search and edit your entries, and can integrate with CalDAV services if you're using a self-hosted contact server (via Nextcloud, for example).

Google Photos is great for automatically saving images in the cloud, organizing them or finding them by facial recognition. But this simplicity conceals the systematic processing of your data: Every image is analyzed, indexed and cross-referenced with your other Google data. Your photos can become an additional source of information, exploited for commercial purposes.

Alternatives:

Simple Gallery is a minimalist open-source application that works entirely offline. It's part of the Simple Mobile Tools suite. It lets you manage, sort, view and edit your images without any data leaving your device. It also features retouching, password protection and a recycle garbage can to recover deleted items. No tracking, no forced synchronization: Your photos stay with you.

Aves is an alternative with a more modern interface. It provides smooth album navigation and advanced organization (tags, filters, sorting, etc.). It requires no Internet connection to operate, and collects no user data.

Ente Photos is an open-source service (clients + servers) for automatic photo backup with end-to-end encryption. Your images are encrypted on the device before being sent, ensuring that even Ente servers can't access them. Ente also offers a self-hosted version for advanced users.

Stingle is both a photo gallery and a camera application, combined with an encrypted backup service. Like Ente, photos are protected by end-to-end encryption. You can use their cloud service (1 GB free) or self-host the Stingle server for total control. The interface is simple, with no ads or trackers.

Alternatives:

Adobe Acrobat Reader, widely used for reading or annotating PDF documents, comes with a number of online functions that can expose your data: Active telemetry, cloud synchronization and the collection of information on your files or reading habits.

MuPDF Viewer is an ultra-light, fast and totally open-source PDF reader. It consumes very few resources. Although it doesn't offer advanced features like annotation or signing, it does its job perfectly: Displaying your documents, without spying.

MJ PDF Reader is a simple, open-source application that lets you read PDF files without advertising or connection to an online account.

Google's Phone application, installed by default on many Android smartphones, works efficiently but collects a significant amount of usage data.

Alternatives:

Koler is an open-source telephony application designed to be beautiful, easy to use and privacy-friendly. It offers a fluid and intuitive interface for managing your calls, without trackers or personal data analysis. However, it does not currently include advanced call filtering or integration with third-party services.

Google Translate is the benchmark in automatic translation, but its use systematically involves sending all your queries to Google, with built-in tracking and possible collection of sensitive data (Translated texts, history, etc.).

Alternatives:

TranslateYou is an open-source translation application that respects the privacy of its users. It works like an interface for various translation engines (LibreTranslate, LingvaTranslate, Mozhi, DeepL, etc.), and lets you choose a service that doesn't exploit your data.

No ads, no trackers, and an easy-to-use interface make TranslateYou a practical alternative to Google Translate.

Yuka is widely used to scan food and cosmetics products and assess their quality, but it relies on an opaque model, with questionable rating criteria, a partially proprietary database and a non-open-source application. What's more, its operation requires connection to a centralized server, with potential collection of usage data.

Alternatives:

OpenFoodFacts is a much more transparent and privacy-friendly alternative. This collaborative open-source project offers a global database, fed by user contributions. Nutritional information, ingredients and labels can be accessed transparently, without abusive data collection.

The mobile application lets you scan barcodes, immediately access product data sheets, and contribute to the database yourself. It's completely free to use, with no advertising or trackers.

Functions such as Quick Share (Android) or AirDrop (iOS/macOS) let you send files between nearby devices via Bluetooth and direct Wi-Fi, without an Internet connection. They are practical, but rely on closed systems, sometimes linked to Google, Samsung or Apple accounts.

Quick Share is now the standard on Android. This software, originally developed by Samsung, was unified in 2024 with Nearby Share by Google, resulting in a single application for file sharing on Android.

Alternatives:

Snapdrop is a free, open-source alternative that requires no installation. It lets you share files between devices connected to the same local network, simply via a web browser. Transfer is direct (peer-to-peer) and data never passes through a remote server.

An interesting alternative is PairDrop (a Fork of Snapdrop), which offers a few extra features.

Warpinator, developed by Linux Mint, makes it easy to transfer files between devices connected to the same Wi-Fi network. It works peer-to-peer, without cloud or third-party server, with a simple interface. Ports exist for Android, enabling files to be transferred between phone and computer.

LocalSend is another free, full-featured alternative with a neat interface. Entirely open-source, this application enables decentralized, end-to-end encrypted file transfers between devices connected to the same local network. No intermediate servers are used, ensuring that your data never leaves your home network.

Applications such as Goodreads, although widely used, raise serious privacy issues. This platform is owned by Amazon, which collects a great deal of data on your reading, preferences, ratings and reviews. In addition, interface relies heavily on user tracking and behavioral analysis for commercial purposes.

Alternatives:

Openreads is the open-source alternative for privacy-friendly reading tracking. This application lets you create a personal digital library, track your reading progress, rate and comment on books, and access recommendations based on your own criteria, without centralized analysis or tracking. All data remains on your device or is synchronized via self-hosted services.

Alternatives:

Available on F-Droid and entirely open-source, Chrono offers a modern, uncluttered interface, with no advertising or data collection. It lets you create customizable alarms: Repetition according to specific days or date ranges, choice of sound, progressive intensity, vibrate, or even tasks to be carried out to deactivate the alarm (Solving a calculation, rereading a text, etc.).

The application also integrates a timer and stopwatch, with lap recording, statistics, time comparisons and multi-timer management. You can configure multiple time zones, customize the theme (colors, styles, animations), and even organize your alarms and timers with labels.

To explore the topic further, I recommend visiting the website Awesome Privacy, which lists the best privacy-friendly alternatives to the software you use daily.

⚠️ Caution: Although the alternatives presented in this chapter are mostly open-source and privacy-oriented, they are not without their limitations or risks. Some may cease to be maintained, have unpatched vulnerabilities, become proprietary or even, potentially, be malware. Some may also be illegal in your local jurisdiction. I have written this chapter in June 2025, but the situation for these applications may have changed since then.

Furthermore, I have not personally audited the code of all the tools mentioned, and my recommendations should in no way be seen as absolute guarantees. It is therefore important for everyone to do their own research before using these applications.