Define the role you need
Building an app can involve product decisions, interface design, frontend implementation, backend services and release operations. One developer may cover some of these roles well without covering all of them. Make the missing responsibilities visible in the budget. Ask who owns technical decisions and who validates the delivered work.
Assess relevant capability
Review projects with comparable integrations or constraints rather than only attractive screens. Discuss code quality, testing, dependency maintenance and incident handling. Specialist experience may justify a different rate. A small, clearly scoped trial milestone can provide useful evidence without committing to the full project immediately.
Calculate the complete engagement
Include coordination, access to other specialists and post-launch maintenance. Decide whether a fixed scope, day-based contract or dedicated team fits your needs. Document payment, ownership and handover terms. Price is meaningful when it is connected to accepted deliverables and the quality of the product you can continue to operate.