This volume contains the proceedings of F-IDE 2016, the third international workshop on Formal Integrated Development Environment, which was held as an FM 2016 satellite event, on November 8, 2016, in Limassol (Cyprus). High levels of safety, security and also privacy standards require the use of formal methods to specify and develop compliant software (sub)systems. Any standard comes with an assessment process, which requires a complete documentation of the application in order to ease the justification of design choices and the review of code and proofs. Thus tools are needed for handling specifications, program constructs and verification artifacts. The aim of the F-IDE workshop is to provide a forum for presenting and discussing research efforts as well as experience returns on design, development and usage of formal IDE aiming at making formal methods "easier" for both specialists and non-specialists.