App development companies usually handle strategy, UI/UX design, development, testing, launch, and ongoing maintenance. Some also provide product research and app store optimization.

App development agencies typically charge between $30,000 and $500,000+, depending on the scope and complexity of the project.

Typical custom app costs by scope include:

• Simple app: $10,000 to $35,000
• Medium-complexity app: $35,000 to $150,000
• Complex app: $150,000 to $300,000+

Most apps take around 3 to 7 months to develop, though the timeline depends on complexity, features, technology, and the development team. Changes in scope, integrations, and testing requirements can also extend the timeline.

• Simple apps: a few weeks to 3 months
• Medium-complexity apps: 3 to 7 months
• Complex apps: 7 to 12+ months 

Look at relevant experience, past projects, technical expertise, communication, and post-launch support. The company should also understand your business goals and target users.

Check whether they have built apps similar to yours and review the usability, design quality, and functionality of their work. Pay attention to projects in your industry or with comparable technical requirements.