Swimlanes.io is a free webapp for making sequence diagrams. You simply edit the text on the left and the diagram is updated in real time. You can download your sequence diagrams as images or distribute with a link.
title: Scenario 3 Mobile/Web App -> Bank Server: Call API of Bank to get temporary credentials or signature Mobile/Web App <- Bank Server: Return temporary credentials or signature Mobile/Web App -> TrustingSocial Server: Call services OCR, Face Matching, Liveness, Tampering,... Mobile/Web App <- TrustingSocial Server: Return eKYC result Bank Server -> TrustingSocial Server: Get result Bank Server -> Bank Server: Verify data