How to choose a web development agency: 9 criteria that actually matter
An honest guide —written by developers— to choosing the right agency. Red flags, key questions, and how to compare proposals without falling for traps.
Hiring a web development agency is, for most companies, one of the more expensive technology decisions of the year. And yet it is often made with the same rigor as choosing an office supplier: by lowest price, or by a casual recommendation.
This article lays out, without decoration, the criteria that actually matter when your website is a strategic tool and not just a business card.
1. Do they hand over the code?
Seems obvious. It is not. A meaningful slice of the market ships websites built on closed platforms, locked templates or proprietary builders where you do not have real access. The day you want to switch providers, you will start from scratch.
Always ask for: full access to the repository, the domain under your name, hosting credentials and minimal deployment documentation.
2. How much JavaScript does your site load in production?
A modern, well-built website ships under 100 KB of JavaScript on first load. Many agencies deliver sites with over 1 MB in JS alone. This has direct consequences for organic ranking and conversion: Google Search prioritizes speed, and mobile users do not wait more than three seconds.
3. Is what gets delivered actually measured?
Ask what Lighthouse score their last shipped project has. If the answer is vague, you already have information. An agency that knows what it is doing delivers sites with 90+ in all four categories (Performance, Accessibility, Best Practices, SEO) from day one.
4. Accessibility is not optional
In the EU, directive EN 301 549 requires public-sector sites to comply with WCAG 2.1 AA. But beyond the legal requirement, accessibility is simply good web development: sites that comply tend to rank better, convert more and age better.
5. Structured data and technical SEO
Concrete questions that tell you a lot:
- Are URLs canonical and standardized?
- Is
hreflangemitted for multi-language sites? - Is there JSON-LD for
Organization,LocalBusinessandBreadcrumbList? - Is a valid sitemap delivered?
- Are images served as AVIF/WebP with correct
widthandheight?
If three or more answers are “I don’t know,” the agency is not ready for serious technical work.
6. Maintenance and support
The day the site goes live, the real conversation starts. What SLA do they offer? How fast do they respond to an incident? Do they have an in-house team or do they subcontract?
A realistic maintenance contract includes: automated uptime monitoring, verified backups (not just “enabled”), regular security patches, and monthly reserved development hours.
7. Proposal: line items, not totals
When you receive three proposals, do not compare by the total. Compare by:
- Hosting and domains — included or separate? In your name?
- Licenses — do you pay later or are they absorbed?
- Design — do they deliver Figma? How many iterations?
- Content — do they write it or do you?
- Translations — for multi-language, by AI, human translator, or you?
- Future changes — what hours are reserved?
Two €6,000 proposals can hide €10,000 of total cost difference over two years.
8. How they work
Ask them to explain how they work, not just what they deliver. Useful questions:
- How many people are assigned to the project?
- Who is your direct point of contact?
- How often are deliveries or demos?
- What tools for tracking (Linear, Notion, Jira)?
- Where does the code live? (GitHub, GitLab, Bitbucket)
- How is it deployed? Is there CI/CD?
An agency without answers is improvising.
9. Real references
Ask to speak with two past clients. If the agency refuses or only offers written testimonials, something is off. Questions for the reference:
- Did they hit deadlines?
- Were there overruns? Why?
- How did they respond when things went wrong?
- Would you hire them again?
Closing
Choosing an agency is not choosing a supplier: it is choosing a technology partner for at least the next two years. If after reading this you have doubts about some of your candidates, use these questions as a filter. The right agency will not only answer confidently, they will thank you for asking.
If you want to talk to us about your project, tell us your case. Within 48 hours you get a concrete reply with initial estimate and schedule.