An estimate that arrives instantly is a bad sign. An experienced provider returns clarifying questions before any number: about who owns the data and what happens on failure. A provider that quotes before understanding the scope is working from a template, fintech development agency and a guess becomes a change request later — at your expense.
Watch for a gap between the engineers on the sales call and the developers actually assigned. Request specific people rather than roles in the contract, with wording covering replacement. A vendor that only offers abstract roles and refuses to name specific engineers is reserving the option to staff you with whoever is free.
Require access to the repository from day one. A team that delivers nothing between demos expects you to take delivery on faith. Daily commits show you who is really on the project far better than a weekly report. This extends to the CI pipeline: if it does not exist, assurances about quality remain nothing more than words.
Loose contract language around code ownership is not an accident. The agreement must state in plain terms that all outputs produced under it belong to your business on payment. Look too at which country’s law applies and the payment schedule: igaming software heavy prepayment with nothing due in return for weeks eliminates the only leverage you have.
Lastly, look at how they communicate. Confirm how much working-time overlap you will share with your timezone, who handles day-to-day questions and within what time. A few hours of overlap generally works; zero overlap turns a five-minute question into a lost day. Sloppy written English in the early emails will not improve later.