Start with proven experience, not the size of the portfolio. Request two rest or graphql three projects that match your domain and your stack, and then find out whether those engineers are still with the company. A solid partner is happy to connect you with the engineers. Answers that name nobody at this stage generally mean the delivery team is not the team you were shown.

The agreement needs more scrutiny than the proposal. Three clauses do most of the work: intellectual property assignment, confidentiality, and exit terms and handover. All the work product must transfer to you on payment, together with documentation, pipelines and deployment scripts. Be careful with any clause that keeps framework code with the vendor, because it is usually exactly the piece that locks you in.

Ask where their numbers come from. An honest estimate is accompanied by a list of assumptions, a breakdown per feature and an explicit range. A fixed price only makes sense when the requirements are stable and documented; when the scope is still moving the provider prices the risk in and you pay for uncertainty either way. A time-and-materials model moves the risk back to the client, so it requires visible weekly reporting and hire smm specialists a spending cap.

How the work is run matters more than team size. Establish what happens when the scope changes, who defines done and how quality assurance works. A team should be able to show you a live build at the end of each sprint. Clear, written acceptance criteria remain your only real protection against an argument at delivery time.

Finally, think about the handover at the start rather than at the end. Ask that the code repository lives on infrastructure you own from day one, and that documentation is updated as part of the work. A partner who is comfortable with this accepts it without argument; a long negotiation over it reveals a great deal.