A quote that comes back within a day counts as a bad sign. A competent team responds with a list of questions: about who owns the data and what happens on failure. A supplier that prices without asking anything is simply guessing, and the gap resurfaces as a change order — at your expense.
Be wary of a mismatch between the engineers on the sales call and the developers actually assigned. Request specific people rather than roles in the statement of work, with wording covering replacement. A vendor that only offers abstract roles and refuses to name individuals is reserving the right to assign anyone it likes.
Insist on the source repository from the first week. A team that delivers nothing between demos is asking you to trust a black box. Regular commits and pull requests reveal the actual pace far better than a slide deck. This extends to the automated test suite: if nothing runs automatically, assurances about quality remain unverifiable.
Loose contract language around IP is not a formality. The agreement needs to state plainly that all deliverables become the property of your company as they are paid seo agency for software companies. Also check the jurisdiction and the payment schedule: heavy prepayment with no deliverable attached eliminates any leverage you would otherwise keep.
Last, examine the working rhythm. Establish what overlap there will be each day, symfony or spring boot which person answers questions and how quickly. Four hours of overlap generally works; none at all converts every clarification into a twenty-four hour round trip. Sloppy written English in the sales phase does not improve under delivery pressure.
