On-line fakturační systém pro malé podnikatele

This thesis examines the needs of small sole traders in relation to established invoicing systems and their features. It focuses in particular on entrepreneurs who regularly work in the field and who could invoice directly at the job site. The aim of the thesis is to design, implement, and test a new online system covering the specific requirements of this target group. In the first stage, a comparative analysis was carried out of the eight most widely used Czech solutions (iDoklad, Fakturoid, Vyfakturuj, Fakturaonline, Fakturovač, mPohoda, FLOWii, and Fakturyweb), comparing both basic and advanced features and, in particular, the presence of specialized functions for field use. The analysis showed that none of the solutions systematically covers the needs of this segment. Across the market, automatic travel-cost calculation, photo documentation with a contextual watermark, and weather logging for the job are all missing; in most cases, a full-screen payment QR code is also still absent, with the exception of Fakturoid and Vyfakturuj. Based on a proto-persona derived from field observation and long-term collaboration with entrepreneurs from the target group, 26 functional requirements for the MVP were defined and prioritized using the MoSCoW method. The system was implemented as a progressive web application (PWA) on the Nuxt 4 framework (TypeScript, Vue 3) with a PostgreSQL database accessed through the Prisma ORM. Alongside a complete invoicing core, it implements precisely the missing field functions: calculation of travel reimbursements, photo documentation with a watermark (time, location, weather), a high-contrast mode for working in direct sunlight, and a full-screen payment QR code. The system integrates the external services ARES, OpenIBAN, Mapbox, OpenWeatherMap, and transactional SMTP; security is based on JWT tokens in httpOnly cookies, RBAC, and OAuth 2.0. Functionality was verified through 56 structured test cases and acceptance testing with six respondents, achieving a success rate of 99%; the application is deployed on the Vercel platform and publicly available. The business model is designed as a subscription with a 30-day free trial period.