Start with domain experience, not the length of the client list. Ask to see two or three case studies that sit close to your domain and marketplace development company your stack, and then find out which engineers actually built it. An honest provider is happy to connect you with the people who would work on your project. Vague answers at this stage almost always mean the demo work came from somewhere else.
The agreement needs a slower read than the pitch. A few clauses carry most of the weight: ownership of the code, confidentiality, and notice periods and handover. Everything produced must transfer to you on payment, together with designs, kubernetes consulting services scripts and infrastructure configuration. Be careful with any clause that leaves so-called reusable libraries outside the transfer, since it is usually the dependency that makes switching painful.
Find out how the estimate was built. An honest estimate is accompanied by the assumptions behind it, a breakdown per feature and a best case and a worst case. A fixed-price contract works only when the scope is genuinely frozen; otherwise the supplier prices the risk in and you pay for it anyway. A time-and-materials model puts the risk on your side, so it needs visible weekly reporting and a spending cap.
How the work is run matters as much as headcount. Establish how a new requirement enters the plan, who defines done and how testing is organised. A team should be able to demonstrate running software rather than status reports. Written acceptance criteria stay the only reliable protection against the it-was-never-in-scope conversation.
Before signing, consider the day you no longer need this vendor while the relationship is still good. Ask that the code repository stays under your account from the first commit, and python development agency that a readme and architecture notes are kept current as the code changes. A partner who is comfortable with this accepts it without argument; resistance at this point says quite a lot.