Product studio · Web, mobile & AI

Your digital product,
thoughtful. Built right.

A senior team turning ideas and business needs into high-performing websites, mobile apps and useful AI solutions — without big-agency overhead.

A human reply within 24 hours · No-obligation first call

Free audit

Test your site’s speed, accessibility and AI visibility.

30 seconds to start the audit. You receive a full 5-dimension report by email, signed 404-DEV, INC.

  • 1PageSpeed & LCP
  • 2SEO & AEO
  • 3Accessibility (axe-core)
  • 4Security & cookies
  • 5Tech stack

Report signed 404-DEV, INC. · No access to your site required · Read-only

10+ yearsof product experience
3 + 1developers & designer
End-to-enddesign, code & launch

What we build

A compact team. Every skill that matters.

No unnecessary sales layer: you work directly with the people designing and building your product.

01 · Web

Websites & web apps

Conversion-focused landing pages, business platforms and fast, accessible SaaS products built to evolve.

Next.jsReactNode.jsSaaS

02 · Mobile

iOS & Android apps

One modern foundation for both stores, fast iteration and a polished native-feeling experience.

React NativeExpoiOSAndroid

03 · AI

Practical business AI

Agents, automation and augmented search that reduce repetitive work and create a measurable advantage.

AI agentsn8nRAGLLMs

Clients & work

Products delivered in demanding environments.

E-commerce, real estate, hospitality, fintech and logistics — experience spanning major brands and early-stage products.

Selected work & collaborations

Fintech · Mobile

Wealthcome

iOS & Android application

Proptech · Web + Mobile

Roomchazer

Multi-platform product

Hospitality · Web

Accor

Accessible experience

Luxury · Mobile

Balenciaga

Bespoke internal tool

Detailed before/after metrics available on request, with the client’s consent.

A straightforward process

From first conversation to launch.

01

Frame

Goals, users, scope and budget: the shortest route to meaningful first value.

02

Design

Journey, interface and architecture are shaped together to avoid surprises.

03

Build

Visible progress, frequent demos and quick decisions with your team.

04

Launch

Production release, measurement and ongoing support guided by real feedback.

Every release passes the same checks: tests, performance budget, accessibility, senior code review.

Senior talent, lean overhead

More expertise. Less agency overhead.

Our lean setup keeps your budget focused on the product. You get an experienced team, transparent scope and technical choices shaped around your reality — not our billing model.

  • Clear scope and estimates
  • Direct access to the team
  • Battle-tested technology
  • Progressive delivery, lower risk

Frequently asked

What clients ask us before we start.

Straight answers, no jargon. Missing a question? Email us and a developer will reply.

Why hire a compact senior team rather than a large agency for a web or mobile product?

A compact senior team puts your budget into design and code, not into sales and management layers. You talk directly to the three developers and the designer who build the product, which speeds up decisions and avoids misunderstandings.

  • No middlemen: the person who estimates is the person who delivers
  • 10+ years of experience on web, mobile and AI products
  • A stable team from framing to launch, with no junior rotation
  • Lower overhead, so more budget goes into the product

How does 404-DEV keep load time fast (LCP under 2.5 s) and sites accessible?

We set a performance budget at design time: Largest Contentful Paint must stay under 2.5 seconds, Google’s “good” Core Web Vitals threshold. Accessibility is tested automatically with axe-core, then checked by hand against WCAG 2.2 level AA.

  • Server rendering (Next.js), optimised images and non-blocking fonts
  • Core Web Vitals tracked: LCP ≤ 2.5 s, INP ≤ 200 ms, CLS ≤ 0.1
  • axe-core tests on every release + keyboard and screen reader checks
  • Relevant since the European Accessibility Act took effect on 28 June 2025

How does business AI (n8n, LLMs) reduce operating costs?

AI cuts costs when it handles repetitive, high-volume tasks: email triage, data entry, document extraction, first-line answers. We connect large language models (LLMs) to your tools with n8n workflows or custom code, and a human approves sensitive decisions.

  • n8n automations linked to your CRM, inbox and files
  • Retrieval-augmented search (RAG) over your internal documents
  • Bounded AI agents: precise scope, action log, human approval
  • We tell you when AI is not the right fit

What does the free 404-DEV website audit include?

The audit analyses the public page of your choice across five dimensions and emails you a report signed 404-DEV, INC. It needs no access to your site and changes nothing: it reads the page like a visitor.

  • Speed: Lighthouse score and LCP
  • SEO and AEO: tags, structured data, readability by AI engines
  • Accessibility: violations found by axe-core
  • Security: HTTP headers, cookies, HTTPS
  • Stack: detected technologies

React Native or native: why one codebase for iOS and Android?

With React Native and Expo, one codebase produces both the iOS and Android apps, which lowers development and maintenance costs. Screens stay native, and we write platform-specific code when the product needs it.

  • One team, one codebase, two stores
  • Faster updates and identical behaviour on both platforms
  • Business logic can be shared with the website

How much does a website or app built by 404-DEV cost?

The price depends on scope: number of screens, integrations, platforms and level of automation. After a free first call, we send a clear estimate split into stages, so you launch what creates value first.

  • No-obligation first call, reply within 24 hours
  • Staged estimates: you can start small
  • Smaller budgets welcome when the scope is realistic

Can you take over an existing product?

Yes. We audit the code and infrastructure, stabilise what needs it, then extend the product. When a focused rebuild is more responsible than a rewrite, we recommend it.

  • Code, performance and security audit
  • Prioritised stabilisation plan
  • Progressive takeover with no service interruption

Where does 404-DEV work, and in which languages?

We work remotely with clients in France, Belgium, Switzerland, Luxembourg, Canada and the United States. We work in English or French.

  • Regular video calls and demos
  • Direct contact by WhatsApp or email
  • Invoiced by 404-DEV, INC.

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Have a product in mind?

Let’s talk about the outcome.

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