Plenty of agencies can build a polished web application. Far fewer have shipped a product where every click moves money, where third-party providers fail at inconvenient times, and where a regulator may ask to see the logs.
The questions below help separate the teams that know the domain from the ones that will learn it on your budget.
Ask about the parts players never see
Wallet design, provider integrations, bonus engines and back-office tools decide whether a platform can be operated day to day. Ask a potential partner how they would handle a duplicated callback from a game provider, or a deposit that succeeds at the payment provider but times out on your side.
Clear, specific answers are a good sign. Vague references to best practices are not.
Look at shipped products, not only designs
Screens in a portfolio show taste. Live products show judgement. Ask which of their projects are running today, what changed after launch, and what they would do differently.
If most of their work is under NDA, as it often is in this industry, ask for a walkthrough on a call instead. A team with real experience can talk through trade-offs without showing confidential material.
Check that design, development and growth talk to each other
Splitting a product across three vendors, one for design, one for development and one for marketing, creates hand-offs where context gets lost. A partner who covers all three, or who has a proven way of working with your other vendors, saves weeks of rework.
Ask who owns the product decisions on their side, and how those decisions reach the people writing code.
Agree on life after launch
Launch is the start of the expensive part. Traffic arrives, bugs surface, markets and regulations change. Before you sign, agree on how support works, how quickly critical issues are handled and how new features are planned and priced.
A partner who is keen to discuss this before the contract is usually one who plans to be around after it.
