Three parts, and you can stop after the first.

The first call

Free, and it usually reshapes the brief. Describe the problem rather than the solution and we will say honestly whether we are the right fit.

The work

A fixed fee per phase, agreed before each one starts. You get a start date and a finish date with the quote. Most first releases are four to eight weeks.

Afterwards

Changes and support by the hour, or a monthly retainer if you would rather not think about it. Either way, the same people.