Awesome Privacy

System-wide Tor proxy, which encrypts your connection through multiple nodes. You can also use it alongside Tor Browser to access .onion sites.

A firewall app for Android, which does not require root. NetGuard provides simple and advanced ways to block access to the internet, where applications and addresses can individually be allowed or denied access to your Wi-Fi and/or mobile connection.

A sandbox environment, allowing you to clone selected apps and run them in an isolated box, preventing it from accessing your personal data, or device information.

An actively-maintained fork of the Island project with additional enhancements

Shows which trackers, each of your installed apps is using, so that you can better understand how your data is being collected. Uses data from the Exodus database of scanned APKs.

Gives you the ability to grant permissions temporarily, so that you could for example use the camera to take a profile picture, but when you close the given app, those permissions will be revoked.

Makes it possible to entirely freeze all background activities on a per-app basis. Intended purpose is to speed up your phone, and prolong battery life, but this app is also a great utility to stop certain apps from collecting data and tracking your actions while running in the background. See on F-Droid

Allows you to protect yourself, your personal space and your possessions - without compromising on security. Leveraging device sensors to monitor nearby space, Haven was developed by The Guardian Project, in partnership with Edward Snowden.

Triggers actions, when certain security conditions are met, such as multiple failed login attempts or monitor settings changed. It does require Tasker, and needs to be set up with ADB, device does not need to be rooted.

Encrypts files and folders client-side, before uploading them to cloud storage (such as Google Drive, One Drive or Dropbox), meaning none of your personal documents leave your device in plain text.

Lets you use CloudFlares fast and secure 1.1.1.1 DNS, with DNS over HTTPS, and also has the option to enable CloudFlares WARP+ VPN.

A network scanner to help you monitor and secure your WiFi network. The app is totally free, but to use the advanced controls, you will need a Fing Box.

An application for Android that uses various techniques to bypass DPI (Deep Packet Inspection) systems, which are used to block some sites (not available on Play store).

This application blocks ads and trackers, doesn't require root and works for all the apps on your Android phone. Check out how it works here.

Collects and analyzes mobile radio data to make you aware of your mobile network security and to warn you about threats like fake base stations (IMSI catchers), user tracking and over-the-air updates. Get from F-Droid

Monitor and control hidden data collection in mobile apps about user behavior/ tracking. Get from F-Droid

Auto-disable Bluetooth, then it is not being used. Saves battery, and prevent some security risks. Get from F-Droid

Auto lock your phone based on movement force/ acceleration. Get from F-Droid See also PluckLock

Prevent background processes gaining unauthorized access to your devices camera. Better still, use a webcam sticker.

Prevent background processes taking unauthorized screenshots, which could expose sensitive data.

Android Firewall+ (AFWall+) is an advanced iptables editor (GUI) for rooted Android devices, which provides very fine-grained control over which Android apps are allowed to access the network. Get from F-Droid

Simple tool, that compares SHA-1 fingerprints of the the SSL certificates seen from your device, and the certificate seen from an external network. If they do not match, this may indicate a man-in-the-middle modifying requests.

An open-source ad-blocker and firewall app for Android 6+ (does not require root).

F-Droid is an installable catalogue of FOSS applications for Android. The client enables you to browse, install, and keep track of updates on your device.