Choosing a development agency means handing your product over to a team you've known for two meetings. The websites all look alike, so do the promises, and the quotes are almost never comparable with one another.
In short: you can recognise a good agency by four things. It has already shipped products close to yours, it lets you talk to the people who will actually work on the project, it delivers continuously rather than at the end of the project, and it leaves you as the owner of the code from day one. The rest (size, location, advertised price) is secondary.
Here is the framework we recommend using, whether you work with us or with someone else.
Start by clarifying your need
You don't choose the same agency to launch an MVP, take over an existing application, or reinforce a team already in place. Before contacting anyone, answer three questions:
- What do you want to ship, and by when? A first version in three months doesn't call for the same organisation as an eighteen-month roadmap.
- Who is steering on the client side? If you have no technical profile in-house, you need an agency that takes on the steering and the trade-offs, not just the execution.
- What is your realistic budget? You don't need an exact figure, but you do need an order of magnitude. It shapes the scope far more than the other way round.
A technical specification of a few pages is enough. The goal isn't to specify everything, but to give every agency the same basis to respond to.
The seven criteria that really matter
1. Verifiable references close to your project
A logo on a home page proves nothing. Ask for detailed case studies, applications you can download, websites you can test, and above all the contact details of one or two clients. A serious agency gives them to you without hesitation.
2. The real seniority of the team
The most useful question in a first conversation: who is going to work on my project, concretely? Many agencies sell with senior profiles and produce with juniors. Ask to meet the lead developer and the person who will run the project before signing.
3. A justified technical stack
A good agency explains its choices in terms of consequences for you: maintenance cost, ease of future hiring, performance, reversibility. Standard, well-documented technologies (React, Next.js, React Native, TypeScript, Node.js) protect you: you will always find someone to take over the code.
4. A method that delivers continuously
The main risk of a classic fixed-price project is the tunnel effect: three months without seeing anything, then a delivery that doesn't match expectations. Insist on frequent deliveries to a test environment, ideally every week, and a tracking tool you have access to.
5. Ownership of the code and the accesses
The code must be versioned in a repository that belongs to you, and the accounts (hosting, app stores, domain name, third-party services) must be created in your name. This is the most often overlooked point, and the one that costs the most when the relationship ends badly.
6. A clear billing model
Fixed price, time and materials, or subscription: each model has its advantages. What matters is that you understand what you are paying for, what happens when the scope changes, and how you can stop. We have detailed the orders of magnitude in how much it costs to develop a SaaS.
7. After the launch
An application needs maintaining: security updates, new versions of iOS and Android, fixes, enhancements. Ask what is planned after going live and at what cost. An agency with no clear answer delivers projects, not products.
Ten questions to ask before signing
- Who will work on my project, and for what percentage of their time?
- Can you put me in touch with two recent clients?
- Which project went badly for you, and what have you changed since?
- How often will I see a testable version?
- Which repository is the code in, and who owns it?
- What happens if the scope changes along the way?
- How do you handle testing and code quality?
- Who is my day-to-day contact, and how quickly do they respond?
- What does maintenance after launch include?
- How does reversibility work if we stop working together?
The third question is the most revealing. Every agency has had a difficult project. The ones that talk about it precisely are the ones that learned something.
The warning signs
- A precise quote after a single call. Pricing seriously requires understanding the need. A firm price without a scoping phase is either inflated or wrong.
- A price far below the market. The gap shows up elsewhere: junior team, undisclosed subcontracting, quality or deadlines.
- No questions about your business. An agency that doesn't try to understand your users will build what is written, not what is useful.
- A proprietary or exotic technology. It makes you dependent on the provider.
- Code delivered "at the end". You must have access to it continuously.
Comparing quotes: the simple grid
| Criterion | What to look at | Recommended weighting |
|---|---|---|
| Understanding of the need | Rephrasing, questions asked, risks identified | 25% |
| Proposed team | Seniority, availability, stability | 25% |
| Method and transparency | Delivery frequency, tools, access to the code | 20% |
| References | Comparable projects, reachable clients | 15% |
| Price | Total cost over 12 months, maintenance included | 15% |
Price deliberately comes last. Between two quotes, the difference in real cost rarely comes from the daily rate. It comes from the number of times things will have to be redone.
Small or large agency, nearby or offshore?
A small senior agency offers direct access to the people doing the work and strong responsiveness. A large agency brings capacity and a broader range of skills, at the price of more intermediaries.
Offshore reduces the advertised rate, but demands solid technical steering on your side. Without an in-house CTO, a nearby team that speaks your language and shares your time zone is almost always more cost-effective over time. If you are still hesitating about the model itself, we have compared agency, freelancer and in-house hiring in detail.
Frequently asked questions
How much does a web and mobile development agency cost in France?
For a French or European agency, expect generally between €8,000 and €25,000 per month depending on the size of the team involved. An MVP most often falls between €20,000 and €60,000. Subscription models start at around €5,000 per month.
Is a specialised or a generalist agency better?
An agency specialised in your type of product (SaaS, mobile application, AI) will move faster and make fewer mistakes than a generalist agency. Sector specialisation is a plus, but technical mastery and delivery method matter more.
How long does it take to develop a first version?
Between two and four months for a properly scoped MVP. Beyond six months without going live, the scope is too broad or the method is the problem.
Do I need to write a specification before contacting an agency?
A short document is enough: objective, target users, must-have features, constraints and indicative budget. A good agency will help you refine the rest during the scoping phase.
Who owns the code developed by an agency?
It must belong to you, and this must be written in the contract: transfer of intellectual property rights as payments are made, code repository in your name, full access to the environments.
👉 Comparing agencies for a web, mobile or AI project? Let's talk for 30 minutes: we'll tell you honestly whether we are the right partner, and if not, who to turn to.