Why is this so hard to get right?

Most clients are not developers. They cannot directly assess code quality, how robust an architecture is, or whether the technical choices make sense. Agencies know this, and some take advantage of it. This guide gives you the tools to evaluate an agency even without a technical background.

The 10 non-negotiable criteria

A portfolio of projects like yours

Ask to see work in your sector, or of comparable complexity. An agency that specialises in e-commerce will not necessarily be the best choice for a B2B SaaS. Look at code quality — ask for GitHub access if you can — not just the visual result.

Client references you can verify

Ask for two or three client contacts you can speak to directly. A serious agency will not hesitate. If they refuse, treat it as an immediate red flag.

A clear, modern technical stack

Be wary of agencies using generic CMS platforms (WordPress, Wix) for genuinely custom web projects. For a serious web application, the stack should include Next.js/React, NestJS/Node.js and a database such as PostgreSQL or MongoDB.

A structured development process

The agency should be able to explain its process: how it gathers requirements, how it delivers (sprints, intermediate deliverables), how it handles bugs after launch. Walk away from anyone who says you will 'figure it out along the way'.

A contract that is clear on code ownership

The code produced should be 100% yours. Some agencies retain the intellectual property, or host your app on their own servers to create dependency. Get this settled in the contract.

Transparency about subcontractors

The senior developer in your sales meeting may quietly become an offshore junior in production. Ask explicitly who will build your project, and whether subcontractors are involved.

Verified Google reviews (4.5+ stars)

Search the agency name on Google Maps and read the reviews. Pay attention to how they respond to negative ones — it tells you a great deal about their professionalism.

Real technical expertise on the sales side

If the person selling to you cannot answer basic technical questions — which database? what hosting? how will you handle load? — be careful. It signals a gap between what is sold and what gets delivered.

Support after launch

What happens once you are in production? How long are bug fixes free? Is a maintenance contract on offer? An agency that vanishes after delivery is not a partner.

Timelines and deliverables in the contract

A project with no schedule is a project that runs late. Ask for a reverse-planned timeline with specific milestones, terms covering delays, and a penalty clause if deadlines slip.

The red flags that should send you elsewhere

✗A price that is far too low (under EUR 5,000 for a complex web app)
✗No contract, or a very vague one
✗Hosting only on their infrastructure, with restricted access
✗An inability to show you the code of an existing project
✗Very slow replies before signature, very fast ones after
✗No client acceptance or validation process
✗No post-launch warranty at all

The questions to ask in a discovery call

Who will be the lead developer on my project? Can I speak to them?
Do you use subcontractors? In France or abroad?
What is your technical stack, and why that choice?
How do you handle bugs after delivery?
Can I see the code of a comparable project?
What happens if you run late? Are there penalties?
Who owns the intellectual property in the code?

Where we stand at Beyond The Brackets

We are not going to pretend to be objective here — we are obviously a candidate if you are looking for an agency. But here is what we actually offer:

A modern stack: Next.js, NestJS, React Native, PostgreSQL
All the code belongs to you, hosted wherever you want
A team based in France, no offshore subcontracting
Shared GitHub from day one — you see everything
Free bug fixes for three months after delivery
A clear contract with milestones and late-delivery penalties
A free first conversation, and a quote within 48 hours

How to Choose Your Web Agency in Paris in 2026: 10 Essential Criteria