SaaS does not fit the workflow
You are paying for 5 SaaS tools to do what one tailored app could do — and the seams between them are where the bugs and the manual work live.
Custom Web Application
Custom Web Application Development for Operating Systems and Internal Tools
When off-the-shelf SaaS no longer fits, SeoMata builds the custom application that becomes your operating system — booking, member portal, scheduling, dashboards, marketplace, internal tools. Modern stack, real production rigor, owned source code.
60+
Custom apps shipped
across SMB and mid-market
99.95%
Uptime SLA
standard hosting tier
< 200ms
p95 latency
on default API surface
100%
Source code yours
no vendor lock
What "custom web application" means here
A custom web application is a piece of software that runs in the browser (and sometimes mobile) and is yours — not a SaaS subscription. It usually starts as "we have outgrown our Notion / Airtable / spreadsheet / off-the-shelf tool" and ends as the operating system that your team works in every day.
SeoMata builds these the same way we build marketing sites — modern stack, real engineering rigor, written documentation, no vendor lock — but with a deeper focus on data model, role + permission design, integrations and the long-term maintainability story.
This page covers when to invest, what types of apps we ship, the default stack, how we build, the quality bar and how cost gets framed. If you are looking for marketing sites, see /design-development/web-development; if you are looking for mobile apps see /design-development/mobile-app-development.
0
Vendor lock
open-source stack, your repo
2
Engineers per project
lead + reviewer
< 1 wk
Production deploy
after acceptance
Decision aid
Six signals you are ready for a custom application
Data spread across tools
Customer / order / scheduling / payment data live in 4+ different systems. Reporting requires manual reconciliation; you cannot answer simple questions about your own business in real time.
Differentiated workflow
The way you operate is part of your competitive edge — and that workflow is not what any SaaS supports out of the box. A tailored app encodes it as a moat.
You charge users for the app
You are building a SaaS, marketplace or portal that customers will pay for. The product itself is the business; off-the-shelf cannot be it.
Compliance demands ownership
HIPAA, SOC 2, GDPR, ISO 27001 — when audit demands you own your data layer and infrastructure, SaaS becomes hard to defend.
Internal tools are scaling badly
Your team built it in Retool / Airtable / Notion and it has worked, but you are hitting the seams. Time to turn it into a real application before the brittleness becomes a liability.
Types
Six application types we have shipped to production
Booking + scheduling system
Multi-staff, multi-location, recurring, integration with calendar + payment + SMS. Used as the operational backbone of service businesses.
Member / patient portal
Login, file access, secure messaging, intake forms, document upload, payment, audit log. Compliance-aware.
Admin dashboard / BI
Operational dashboards aggregating data from CRM / payments / inventory / ad spend. Replaces "the spreadsheet I update every Monday".
Marketplace / multi-tenant SaaS
Customer-facing SaaS, marketplace, tenant management, billing, role-based access, white-label.
Internal tools (CRM, ATS, ops)
Custom CRM, applicant tracking, dispatch board, route planning, fleet management. Built once, maintained for years.
Customer-facing configurator
Product builder, quote generator, lead-qualification flow, embeddable widget. Marketing + ops + ecommerce all benefit.
Stack
Our default stack for custom apps
Next.js + TypeScript
App Router, Server Components, Server Actions where it fits. Used for both customer-facing and internal apps. Same language across front-end + back-end speeds the team.
Postgres on Neon / Supabase / RDS
Postgres is the default — proven, predictable, well-tooled. Supabase or Neon for early-stage; RDS or managed clusters for scale.
Auth via Clerk / NextAuth / Auth0
Auth choice depends on use case. Clerk for fast-start B2C, NextAuth for full-control B2B, Auth0 for enterprise compliance.
Drizzle / Prisma ORM
Type-safe schema, migrations as code, no N+1 surprises. Drizzle for performance-sensitive paths, Prisma for ergonomics.
tRPC or REST + OpenAPI
tRPC for internal apps where front-end + back-end ship together; REST + OpenAPI when third-party integration matters.
PostHog + Sentry
Product analytics + funnel + replay (PostHog); error monitoring + alerting (Sentry). Both wired on day one, not at launch.
Process
Six-stage custom-app build process
Discovery + spec
User research, workflow mapping, data model design, integration inventory. Output: written spec including data model + API surface + permission matrix.
Architecture + foundation
Repo, CI/CD, deploy pipeline, auth, base layout, error monitoring. Hello-world deploy in week one on production-grade infra.
Vertical slice
One end-to-end flow shipped (UI → API → DB → integration) so the team sees something working before the build deepens.
Build out + integrations
Remaining flows + integrations (calendar, payment, SMS, CRM, ERP, etc.) wired against staging credentials.
QA + perf + accessibility
Cross-device + multi-role QA, perf test on the API surface, axe-core pass on web UI, accessibility statement.
Launch + 30-day care
Production deploy, monitoring active, weekly checkpoints for 30 days, runbook handed off.
Quality
Quality bar every custom app meets
Type safety end to end
TypeScript across UI + API + DB schema. Type errors caught in CI, not in production.
Auth + roles + audit log
Roles + permissions matrix, audit log on sensitive actions, session management.
API documentation
OpenAPI spec or tRPC types exported; auto-generated client SDK if external consumers exist.
Test coverage on critical paths
Unit + integration tests for auth, billing, data mutation, integrations. Not 100% — but the right 30%.
Background jobs + queues
Inngest / BullMQ / native queue, with retry + dead-letter handling. No "spawn a setTimeout and pray".
Error monitoring + alerting
Sentry (or equivalent) wired to PagerDuty / Slack; production errors page the on-call.
Backup + recovery
Automated daily backup, tested restore on quarterly cycle, written disaster-recovery runbook.
Documentation + runbook
Architecture diagram, deploy guide, env-var reference, integration owner list, on-call escalation.
Portfolio
Recent custom-app work
Investment
How custom-app cost usually breaks down
Custom application work is more variable than marketing-site work because the scope variable is the data model, not the page count. The three things that move the number most are: the complexity of the data model (5 entities vs 30), the complexity of the permission + multi-tenancy story (single-tenant SMB vs multi-tenant SaaS), and the number of integrations.
A typical SeoMata custom-app MVP — clear scope, modern stack, 8–12 weeks of focused build — lands between USD 40,000 and USD 110,000. Larger SaaS or marketplace platforms run USD 120,000–320,000 for a 4–7 month build to a defensible v1. We share a phased estimate during scoping so you can choose where to draw the v1 line.
Operational cost after launch is usually USD 2,500–6,500/month on a retainer if SeoMata stays on. The retainer covers backlog work, monitoring + incident response, infrastructure upkeep, security patches and quarterly architecture review. Many clients choose to take ownership in-house after 6–12 months; we make that path explicit from kickoff.
Common questions about custom-app engagements
Will we own the source code?
Yes. Repo is in your GitHub org from day one. No deployment dependencies on us; you can revoke our access and the app keeps running.
How long does a typical MVP take?
8–12 weeks for a focused MVP with clear scope. Multi-tenant SaaS or marketplace builds typically need 16–28 weeks to reach a defensible v1.
Can you work with our existing engineers?
Yes — about a third of our app engagements are co-builds where SeoMata leads architecture + initial build and your team contributes during build and owns post-launch. We document hand-off boundaries up front.
What about mobile?
We build mobile apps as part of /design-development/mobile-app-development. The default pattern is web app first + mobile when the user behaviour justifies it; the same API + data model serves both.
What stack do you recommend?
For most custom apps: Next.js + TypeScript + Postgres + Drizzle/Prisma + Clerk/NextAuth + tRPC (or REST + OpenAPI). For very specific niches we will recommend different stacks (e.g. Django for science-heavy applications, Rails for fast-prototype B2C marketplaces).
Will you handle hosting / DevOps?
Yes. Default is Vercel + Neon / Supabase. For enterprise: AWS or GCP with infrastructure-as-code (Terraform) and a dedicated DevOps engineer.
Ready to scope a custom application?
Start with a free 45-minute scoping call. We will listen to the problem, the current tools, the workflow and the constraints, then write back with a one-page architecture sketch and a rough budget range — usually within 5 business days.
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Next step
Get a Free Workflow Discovery Call
Book a free workflow discovery call. SeoMata will trace the manual steps worth automating first, and tell you honestly whether a custom web app, a SaaS extension, or a no-code prototype is the right next move.