Communication

Application name	Description	Availability		License	APIa	Note
		Google Play	F-Droid
ConnectBot	SSH, telnet, and terminal emulator	Yes	Yes	Apache 2.0	1.5+
CSipSimple	SIP & VoIP client	Yes	Yes	GPLv3	1.6+
Jitsi	Videoconferencing and instant messenger	Yes	Yes	LGPLv2.1	?
K-9 Mail	Advanced email client	Yes	Yes	Apache 2.0	2.2+	Supports OpenPGP integration with OpenKeychain
Linphone	Video SIP/VoIP client	Yes	Yes	GPLv2	2.2+
Element	Federated instant messaging and group chat client using the Matrix protocol.	Yes	Yes	Apache 2.0	4.1+
Sipdroid	SIP/VoIP client	Yes	Yes	GPLv3	2.0+	works on 1.5
WordPress	Official WordPress client	Yes	No	GPLv2	2.3+
Zulip	groupware and chat	Yes	No	Apache 2.0	5.0+	Also available for iOS

Privacy/security focusededit

Application name	Description	Availability		License	APIa	Note
		Google Play	F-Droid
APG	OpenPGP and key management	Yes	Yes	Apache 2.0	1.5+	OpenKeychain available as more up-to-date alternative
Briar	Peer-to-peer encrypted messaging and forums	Yes	Yes	GPLv3	4.0+
Conversations	Federated encrypted instant messaging and group chat	Yes	Yes	GPLv3	4.0+	Interoperable with any Jabber/XMPP clients. End-to-end encryption using OMEMO, OpenPGP (and OTR for versions under 2.0 and the legacy version).
Element (formerly Riot)	Decentralised, encrypted chat & collaboration powered by Matrix	?	?	Apache 2.0	5.0+
I2P	Anonymizing network layer	Yes	Yes	Apache 2.0	2.3+	I2P also maintain their own F-Droid repo.
IVPN	Privacy-focused VPN service	Yes	Yes	GPLv3	?	Open source apps on all platforms (Windows, macOS, Android, and iOS) and undergo an independent security audit.
Jami	Softphone and messenger utilizing DHT and strong cryptography	Yes	Yes	GPLv3	?
Lantern	Peer-to-peer internet censorship circumvention	Yes	No	Apache 2.0
Mullvad	Privacy-focused VPN service	Yes	No	GPLv3	?	Open source apps on all platforms (Windows, macOS, Android, and iOS).
OpenKeychain	OpenPGP and key management	Yes	Yes	GPLv3		Integrates with K-9 Mail.
Orbot	Client and proxy for Tor anonymity network	Yes	Yes	BSD/GPL	1.6+
Psiphon	Client for internet censorship circumvention system	Yes	No	GPLv3	?
ProtonMail	Client end-to-end encrypted email service	Yes	No	GPLv3	?	Open source apps on WEB app, Android, IOS, Bridge app.
ProtonVPN	Privacy-focused VPN service	Yes	Yes	GPLv3	?	Open source apps on all platforms (Windows, macOS, Android, and iOS) and undergo an independent security audit.
Signal	Encrypted instant messaging, voice and video calling	Yes	No	GPLv3	2.3+	Also available for iOS. The Android client is a merger of the former TextSecure and RedPhone apps.
Surespot	Encrypted instant messaging	Yes	Yes	GPLv3+		Also available for iOS. F-Droid build is based on forked repo.
Telegram	Client for cloud-based messaging platform	Yes	Yes	GPLv2	2.2+	Also available for iOS. F-Droid build is based on forked repo. Server uses closed source software.
Tox	peer-to-peer instant-messaging	Yes	Yes	GPLv3+	4.0+	Alpha release
Tutanota	Client for end-to-end encrypted email service	Yes	Yes	GPLv3	?
Wire	Encrypted instant messaging, voice and video calling	Yes	No	GPLv3		Also available for iOS, Windows and OS X. Server uses closed source software.