A quote that comes back within a day counts as a bad sign. A competent team will come back with questions first: about users and volumes. A provider that prices without asking anything is simply pricing a guess, and symfony or spring boot a guess becomes a change request later — at your expense.
Look out for a gap between the dedicated team vs freelance developer in the pitch and those who eventually appear in the repository. Ask for specific people rather than roles in the agreement, with a clause covering replacement. A team that only offers roles and never names people is preserving its own flexibility at your cost.
Require commit-level visibility from the first week. A partner that hands over nothing between demos expects you to accept a black box. Visible commits reveal the actual pace far better than a slide deck. The same holds for the build and deployment setup: if nothing runs automatically, promises about quality are nothing more than words.
Loose wording in the contract around intellectual property is never a formality. The agreement must state explicitly that all outputs produced under it transfer to your staff augmentation company on payment. Check also the governing law and how payments are structured: a large upfront payment with nothing due in return for weeks takes away your only leverage.
Lastly, blockchain web development company examine how they communicate. Establish how much working-time overlap the teams will share with your working day, which person handles your questions and how quickly. A few hours of overlap generally works; zero overlap stretches each small question into a day of delay. Careless writing in the early emails does not improve once the work starts.