[7] Its beta version was first launched on May 25, 2010, by Whisper Systems,[1] a startup company co-founded by security researcher Moxie Marlinspike and roboticist Stuart Anderson.

[20][22] Toward the end of July 2014, Open Whisper Systems announced plans to unify its RedPhone and TextSecure applications as Signal.

[26][27] Later that month, Open Whisper Systems ended support for sending and receiving encrypted SMS/MMS messages on Android.

[32] The user could define a time period after which the application "forgot" the passphrase, providing an additional protection mechanism in case the phone was lost or stolen.

[33] Group chats were automatically end-to-end encrypted and held over an available data connection if all participants were registered TextSecure users.

From March 2015 forward, TextSecure's message delivery was done by Open Whisper Systems themselves and the client relied on GCM only for a wakeup event.

[40] It does not provide anonymity preservation, and requires servers for the relaying of messages and storing of public key material.

[40] In addition to the properties provided by the one-to-one protocol, the group chat protocol provides speaker consistency, out-of-order resilience, dropped message resilience, computational equality, trust equality, subgroup messaging, as well as contractible and expandable membership.

[41] Once the server removed this layer of encryption, each message contained either the phone number of the sender or the receiver in plaintext.

In December 2013, it was announced that the messaging protocol that was used by TextSecure had successfully been integrated into the Android-based open-source operating system CyanogenMod.

[2] TextSecure was briefly included in the F-Droid software repository in 2012, but was removed at the developer's request because it was an unverified build and exceptionally out of date.

Open Whisper Systems have subsequently said that they will not support their applications being distributed through F-Droid because it does not provide timely software updates, relies on a centralized trust model and necessitates allowing the installation of apps from unknown sources which harms Android's security for average users.

[36] In October 2013, iSEC Partners published a blog post in which they said that they had audited several of the projects supported by the Open Technology Fund over the past year, including TextSecure.

[39] Among other findings, they presented an unknown key-share attack on the protocol, but in general, they found that the encrypted chat client was secure.

[54][55] In October 2014, the Electronic Frontier Foundation (EFF) included TextSecure in their updated Surveillance Self-Defense guide.

[57][58] TextSecure received points for having communications encrypted in transit, having communications encrypted with keys the providers don't have access to (end-to-end encryption), making it possible for users to independently verify their correspondent's identities, having past communications secure if the keys are stolen (forward secrecy), having their code open to independent review (open-source), having their security designs well-documented, and having recent independent security audits.

As of October 2016[update], the project has received an unknown amount of donations from individual sponsors via the Freedom of the Press Foundation.

[60] Open Whisper Systems has received grants from the Knight Foundation,[61] the Shuttleworth Foundation,[62] and the Open Technology Fund,[63] a U.S. government funded program that has also supported other privacy projects like the anonymity software Tor and the encrypted instant messaging app Cryptocat.