These days, privacy and security are out the window. In 2018 and already during 2019, we've seen some of the biggest exploits and privacy invasion to date; everything from people's bank records being leaked due to improper security, to the various scandals of Facebook, and even our home devices such a basic TV tracking everything you do.
Exodus is a great tool for Android (available on web or F-Droid), allowing you to scan your installed applications and get a full report on what permissions the application asks for and what trackers it has built in.
Below, I'll list some of my choices for alternatives that are free (as in freedom) and protect your privacy.
This is a Pixel-like launcher that is highly customizable. Although its been in "alpha" stage for quite some time, I've yet to experience any bugs with it and is very stable based on my experience. It is also actively developed, with updates being pushed out weekly.
Another great launcher which takes a whole new approach is KISS. KISS is a geared to be a very minimal launcher with simply lists your frequent apps on the bottom row and your main screen consists of all your previous/recent apps accessed. Its extremely lightweight, out-of-the-way, and a fresh experience.
Fennec / Klar
Fennec is the latest release of "Firefox for Android" with proprietary bits removed. Firefox is rock solid on Android alternative to Chrome. Not only is it more privacy-friendly but it allows for extensions to be installed such as uBlock Origin, HTTPS Everywhere, etc. Firefox Sync also works between devices flawlessly and supports integration with KDE Konnect. Klar, similar to Fennec, is the "Firefox Focus for Android" version with proprietary bits removed.
TOR of course, allows for the most privacy. TOR is a network powered by other TOR users. You become anonymous as you're routed through different relay connections before hitting the final destination. The browser itself is a modified Firefox release with a wealth of tools to help your remain anonymous to the "web lords", tracking, and more.
GBoard "phones home" to build better suggestions about your typing, but who knows what else it's storing about what you type? I have limited experience with other keyboards, however this one caught my eye and I needed not to look any farther.
AnySoftKeyboard is completely customizable with a wealth of options, gestures (including swipe-to-type), many themes (I find the "Dark ASOP" theme the most GBoard-like), and extensions. Its actively developed and features alternative languages through extensions as well.
Markor is a feature-rich markdown editor with support for todo.txt. Nothing is stored in the cloud but because everything is offline it supports any sync client such as OwnCloud, NextCloud, Seafile, Syncthing, or anything else which simply watches a directory.
Markor is great for storing notes, draft blog posts, recipes or anything you can store in markdown or plaintext format.
Simple File Manager
Simple File Manager provides an basic interface for managing your files stored locally and on any SD card attached to the phone. It features a quick search, bookmarking, password protection, and more.
Syncthing replaces proprietary sync and cloud services with something open, trustworthy and decentralized. Putting you in control of your files and keeping them out of the cloud. You have the ability to add approved devices to share folders on any device with any other device. It has support for iOS, Android, and comes with a handy web-client for easier configuration. As well, it comes with several built-in options for file versioning.
Tasks is a open source fork of the Astrid app. A great material-designed app to keep your self on track. Its full featured with categories, priorities, location-based tasks, voice clips, and more.
Bitwarden is a cross-platform password management tool. Its easy to use and can help you store logins for websites, logins for databases, logins for servers, credit cards, notes, and more. It also features built-in TOTP for two-factor authentication. Extension for Firefox is also available.
FreeOTP is a two-factor authentication (2FA) application for systems utilizing one-time password protocols (OTP). Tokens can be added easily by scanning a QR-code or by manually entering in the token configuration.
FreeOTP implements open standards. This means that no proprietary server-side component is necessary: use any server-side component that implements these standards
QKSMS is an open source, material designed, SMS/MMS app. It features a customizable interface, with dark mode, scheduled messages, message pinning, searching, media access, and more.
An open source GitHub Android client app, faster and concise. It allows you to manage your profile, repositories, issues, and more. The only downside I find is theres no difference inside the app for what is an issue and what is a PR. So if someone submits a PR, you can not view the changes from the app.
By default, Android does not support CalDAV/CardDAV (probably because Google wants you stuck on their services). This simple app allows you to connect to DAV services such as Mailbox.org, PrivateEmail.com, FastMail.com, and more. You're able to pull in and sync two-way: your contacts, your calendars, your tasks (via calendar), and mail.
RedMoon is a "night shift"-like app which filters out blue light at night. This helps your eyes at night, and prevents the blue light from interfering with production of Melatonin. It features a schedule, or location-based scheduling, with several features for screen color, temperature and more.
ScreenCam allows you to record your screen (and voice). It features settings to pause/resume recordings, bit rates, resolutions, audio sources, and more.
Of cource, there's more open source apps for calendar, email, etc. Explore and find out what you can replace on your phone with a more open source and privacy-abiding alternatives.