Begin with proven experience, not the size of the portfolio. Request three or four engagements that sit close to your domain and your stack, and then ask whether those engineers are still with the python development company. A serious vendor will put you on a call with the engineers. Evasive answers at this stage almost always mean the delivery team is not the team you were shown.

The contract warrants more scrutiny than the proposal. A few clauses carry most of the weight: it consulting services intellectual property assignment, confidentiality, and exit terms and react native vs flutter handover. All the work product must transfer to you on payment, along with documentation, pipelines and deployment scripts. Be careful with any clause that leaves framework code outside the transfer, as it is usually exactly the piece that locks you in.

Ask how they estimate. A credible estimate arrives with a list of assumptions, a breakdown per feature and nextjs development company an explicit range. A fixed price only makes sense when the specification is complete; otherwise the supplier adds a risk premium and you pay for it anyway. A time-and-materials model shifts that risk to you, so it needs a cap, regular demos and transparent reporting.

How the work is run matters more than the number of developers. Ask how change requests are handled, who signs off on a feature and how quality assurance works. A well-run team will be able to walk you through a working build every one or two weeks. Clear, written acceptance criteria stay the only reliable protection against endless rounds of rework.

Finally, consider the end of the engagement while the relationship is still good. Require that the repository lives in your organisation from the first commit, and that documentation is written as you go rather than left to the end. A provider confident in its own work will agree quickly; resistance at this point says quite a lot.