Every development company in London will tell you they are senior, agile, and client-focused. None of that is checkable. What follows is twelve questions that are, and what the answers tend to mean. We are one of the companies you might be evaluating, so read this with that in mind. It is written the way we would want to be assessed.
Before the questions: decide what you are buying
There are three different purchases hiding behind "we need an app":
- A team: you have a product manager and a plan; you need hands.
- A product partner: you have a business problem; you need someone to decide what to build as well as build it.
- A supplier: you have a specification; you want it delivered to price.
Most disappointment comes from buying one and expecting another. A supplier will build your spec exactly, including the parts that are wrong. A product partner will push back, or recommend another approach to tackle the same problem, which is what you are paying for.
The twelve questions
1. How is AI coding used in your company?
Watch out for two extreme realities: a team doesn't use any AI, or all the work is done with it. AI-assisted development with human oversight strikes the perfect balance: AI as a junior developer with experienced QA engineers going through the app and a product owner giving a clear prompt to the AI. A senior developer that reviews the code and verifies the architecture is a must.
2. What happens to the estimate when we want to change something?
There is one right shape of answer: we tell you, we re-plan, you decide. Any answer that implies the estimate never moves is describing a padded price or a coming argument.
3. How do you handle product discovery?
Jumping straight into coding without a proper discovery puts both parties at risk. But even if a team starts with discovery, it doesn’t ensure success on its own. The first phase should typically result in a product statement, a prioritised backlog, a user journey map, and a clear delivery plan.
4. Who owns the IP, and when does it transfer?
The right answer is: you do, from the first commit. Anything staged behind final payment is a lever, and it will be pulled if the relationship goes wrong.
5. Where does the code live during the project?
In your repository, ideally. If it lives in theirs until handover, you cannot see progress and you cannot leave.
6. What’s involved in a project price beyond actual development?
Pay attention to the things that may feel extra: quality assurance, regression testing, product ownership, environment setup, and deployment. Teams that don’t set aside sufficient time on this (at least 30% of dev for QA, and at least 20% for product ownership) might be sacrificing quality.
7. How do you handle security and data protection?
For a UK project, expect specifics: where data is hosted, what is encrypted, who has production access, how a subject access request is served, what happens on a breach.
8. What does support look like after launch, and what does it cost?
A number and a response time. "We'll be there for you" is not a support agreement.
9. What have you got wrong recently?
The single most useful question in the list. Companies that cannot answer it either have not delivered enough to have failed, or are not telling you the truth.
10. Can I talk to any of your past clients?
Look beyond 5-stars and one-line client testimonials. Speaking to a real past client will tell you much more about the vendor than a written review would.
11. What would you do if we halved the budget?
The good answer is a smaller product, or an alternative approach. The bad answer is the same product with fewer hours, which is the same product with worse engineering.
12. What do you need from us to succeed?
A partner who has thought about delivery will have a list: a decision-maker, access to users, a test environment, sign-off within 48 hours. Suppliers say "nothing".
London-specific things worth checking
- Rates. A senior developer in London bills roughly £550–£850/day through an agency. Materially below that means the work is happening somewhere else, which can be fine, if a provider is open about it.
- Time zones. Distributed teams work. Undisclosed distributed teams do not, because you discover the overlap problem after signing.
- Contract law. Insist on a UK entity, English law, and clarity on what happens to the code and the accounts if either side walks away.
After the questions
Shortlist two, pay both for a small piece of paid discovery, and compare what comes back.
Two weeks and a few thousand pounds spent choosing is cheap next to six months spent with the wrong partner. If you want to see how we answer these ourselves, the plainest versions are on the software development company in London overview, and on the mobile app development company and bespoke software development pages — including the prices, which is where most agency websites stop being specific.