Start with relevant experience, not the size of the portfolio. Request two or three case studies that sit close to your stack, and then find out which engineers actually built it. A solid partner will introduce you to the people who would work on your project. Answers that name nobody at this stage usually mean you are talking to a reseller.

The paperwork deserves more scrutiny than the proposal. Three sections matter more than the rest: intellectual property assignment, confidentiality, swift development outsourcing and exit terms and handover. All the work product has to transfer to you as it is paid for, together with source code, designs and infrastructure as code. Look closely at any clause that leaves reusable components in the vendor's hands, nearshore development company as that is often exactly the piece that locks you outsourcing versus in house software development.

Ask where their numbers come from. An honest estimate comes with a list of assumptions, a breakdown by feature or module and an explicit range. A fixed-price contract is only reasonable when the specification is complete; when the scope is still moving the vendor adds a risk premium and you pay for uncertainty either way. Hourly billing moves the risk back to the client, so it requires visible weekly reporting and a spending cap.

How the work is run matters as much as the number of developers. Ask what happens when the scope changes, who signs off on a feature and what the QA setup looks like. A team should be able to walk you through a live build at the end of each sprint. Written acceptance criteria remain your only real protection against endless rounds of rework.

Finally, think about the day you no longer need this vendor while the relationship is still good. Require that the code repository lives under your account from day one, and that documentation is updated as part of the work. A provider confident in its own work says yes immediately; resistance at this point reveals a great deal.