The Replicant project started in mid-2010 with an effort to consolidate various initiatives attempting to produce a fully free-as-in-freedomAndroid derivative for the HTC Dream. The original team consisted of Bradley M. Kuhn, Aaron Williamson, Graziano Sorbaioli and Denis ‘GNUtoo’ Carikli. The project quickly led to the writing of replacement code for the non-free parts that were required to make the HTC Dream functional. The first component to be replaced permitted audio to work without a proprietary library. Replicant originally provided its own FOSS application repository, which was later replaced by F-Droid.
The software that was in charge of handling the communication with the modem (which is called Radio Interface Layer – RIL) was then replaced by free code, thus making the telephony part usable. A library handling the GPS was then adapted from free code that was originally written for another phone and permitted the HTC Dream to have GPS working with Replicant.
As development continued, many members of the original Replicant team retired from the project, making Denis "GNUtoo" Carikli the only remaining member from the original team still actively working on the project. In April 2011, Paul Kocialkowski decided to get involved with the project and gradually became the main Replicant developer, after successfully porting it to the Nexus S and Galaxy S devices.
Replicant is sponsored and supported by the Free Software Foundation.
In March 2014, Replicant developers found and closed a backdoor present in a wide range of Samsung Galaxy products that allows the baseband processor to read and write the device's storage, sometimes with normal user privileges and sometimes as the root user depending on device model. It is unknown whether Samsung's proprietary firmware for the radio chip can be remotely instructed to use these access features and whether the vulnerability was introduced with legitimate uses in mind.
On January 3, 2013, the project released Replicant 4.0 SDK as a fully libre replacement to Android SDK. The Replicant SDK was released in response to Google updating the license for add-ons and binaries under a proprietary agreement.
Scope of the Replicant project has been gradually expanded to include support for new devices, starting with the Nexus One, Nexus S and Galaxy S. Replicant developers are continually working to add support for new devices. As of January 2014, the following devices are supported, with Wi-Fi and Bluetooth requiring proprietary firmware in order to work:
Additional target devices are evaluated, based on the suitability of their hardware plaftorms and required device drivers; as of January 2014, devices listed below are not yet supported, and porting Replicant to them is only in consideration.