Domain model
The objects and permissions your business actually runs on.
Service 09
Custom Web Apps
Templates stop where your process starts. We design and engineer custom web applications around the way your team actually works.
custom web application development
Custom Web Apps
8–16
Weeks for a focused MVP
TS
TypeScript-first codebase
0
Auth & role model, not a plugin soup
docs
Handoff your engineers can inherit
The work
CustomWebApps
The4Loop builds custom web apps as long-lived products: TypeScript, Next.js, auth, roles, and the unglamorous workflows that save hours. Marketing website design can sit in front; the app holds the system of record. We leave documentation and a codebase your team can inherit.
- Next.js and TypeScript architectures built to scale
- Auth, roles, and workflow-specific product surfaces
- Performance, SEO, and maintainability from the first commit
Engagement
- Typical timeline
- A focused MVP is typically eight to sixteen weeks. Multi-team products run longer on a retained squad.
- Investment
- Professional and Enterprise. Discovery produces a milestone plan you can track from week one.
Figures describe typical ranges for this practice. Scope and numbers lock in discovery — not in the brochure.
Get a scoped quoteWhat we build
Deliverables,notvibes
Product UI
Dashboards, tables, and workflows dense enough for daily use.
Auth & roles
Who can see and do what — including the awkward admin cases.
Integrations
Your APIs, billing, and identity — not a greenfield fantasy.
Performance
Budgets for the screens people live in. Lists that do not fall over at 10k rows.
Handoff kit
Repo, environments, and documentation so an internal hire is not starting from folklore.
How we work
Apathyoucantrack
01
Map the work
We sit with the people who will use it. The app is the job, not the org chart.
02
Slice the MVP
One vertical that is useful on its own. Everything else waits.
03
Build in the open
Weekly demos on real data. Design and engineering stay in the same thread.
04
Harden & inherit
Observability, docs, and a joint sprint with your engineers if they are taking it.
Fit
Who this is for
- Internal tools that outgrew spreadsheets and Notion
- Customer portals that cannot be a theme plus plugins
- Products whose process is the moat — templates will not fit
Stack we use
Next.jsTypeScriptPostgresAuthReactAPIs
Tools are chosen for the job — not for a logo wall. If a simpler stack is enough, we will say so.
Testimonials
Partners,notvendors
The same senior team from brief through launch — on this practice and the ones around it.
“The4Loop behave like an embedded product team, not an agency on the sidelines — strategy, design, and engineering in one thread.”
AC
Amelia Cho
CEO
“We needed craft and serious engineering in one partner. They shipped a web experience and a mobile suite that finally matched the ambition of the product.”
MT
Michael Torres
Founder
“Their AI practice is unusually pragmatic — clear guardrails, thoughtful UX for model outputs, and documentation a compliance team can actually use.”
EW
Emma Williams
CTO
FAQ
CustomWebAppsquestions
Scope, timeline, and how the work actually runs — before you book a call.
Website design is the public, conversion-led surface. A custom web app is logged-in product — dashboards, portals, admin, and domain-specific tools.
Related
Keepexploring
Website Design
Marketing websites that make a first impression count — fast, accessible, and built to drive trust and action.
View serviceCustom Mobile Apps
Custom iOS and Android apps built around your product — not a template — from prototype to App Store and Play Store.
View serviceDevOps Automations
CI/CD, infrastructure as code, and delivery pipelines that cut wait time — so releases stay predictable, fast, and repeatable.
View serviceThe4Loop — ready when you are
Readytostart?
CustomWebApps
Tell us the outcome you need — we will reply within one business day with a clear next step.
Free consultation
24h response
Senior specialists