Lexoffice.login

Future work could explore automated refresh token handling and background token refresh in SPAs using Web Workers. The principles outlined here are transferable to any OAuth2‑protected financial API. [1] lexoffice API Documentation. Authentication . Retrieved from https://developers.lexoffice.io/docs/#authentication [2] IETF RFC 6749 – The OAuth 2.0 Authorization Framework. [3] IETF RFC 7636 – Proof Key for Code Exchange (PKCE). [4] OWASP. OAuth 2.0 Security Cheat Sheet . [5] lexoffice OpenID Configuration – https://login.lexoffice.io/.well-known/openid-configuration Appendix – Full Token Response Example

– lexoffice, OAuth 2.0, PKCE, API security, cloud accounting, single-page application (SPA), authentication flow. 1. Introduction lexoffice is a leading cloud accounting software for small and medium-sized enterprises (SMEs) in Germany. Its API (documented at https://developers.lexoffice.io ) enables automated invoice creation, contact management, and financial reporting. All API endpoints require authenticated access, governed by the lexoffice.login process. lexoffice.login

# Exchange data = "grant_type": "authorization_code", "code": auth_code, "redirect_uri": self.redirect_uri, "client_id": self.client_id, "code_verifier": self.code_verifier resp = requests.post(self.TOKEN_URL, data=data) resp.raise_for_status() tokens = resp.json() return tokens # contains access_token, refresh_token, expires_in Future work could explore automated refresh token handling

Abstract Modern cloud accounting platforms like lexoffice provide RESTful APIs for integrating financial data into third-party applications. A critical component is the authentication flow, typically encapsulated as lexoffice.login . This paper analyzes the design, implementation, and security considerations of lexoffice’s login mechanism based on OAuth 2.0 with Proof Key for Code Exchange (PKCE). We present a reference implementation, discuss common integration pitfalls, and evaluate the trade-offs between security and usability. The findings provide a blueprint for developers integrating lexoffice or similar FinTech APIs. Authentication