Custom Development
Web application development company for UK businesses
SaaS platforms, portals, dashboards and internal tools, with the sign-in, billing and admin they need planned from the start. A fixed written quote after a free call.
In short
A web application is software people use in a browser, such as a SaaS platform, customer portal, dashboard or internal tool. APPS 365 is a UK company that designs, builds and supports web apps and SaaS products, including sign-in, billing and admin, with a fixed written quote before work starts.
What worries people about a web app build
A web app has to do more than look right. It has to take payments, keep accounts separate and keep running as more people use it.
You want revenue early, but billing gets left until last.
Subscriptions, trials and invoices are part of the first scope, so the product is ready to charge when you are.
You fear building something that cannot grow.
We design the data and structure around how you expect to grow, and build only what the first version needs.
You are unsure about the technology and hosting costs.
We explain the choices and the likely running costs in plain English before you commit.
Security and UK GDPR are a concern.
Access controls, separated customer data and logging are designed in from the start, and we talk through UK GDPR with you.
What you get from a web app build
Built around your use case
We start from what your users need to get done, then build only the screens and features that support it.
Sign-in and roles
Email and password, social login or Microsoft sign-in, with separate roles for users, managers and administrators.
Billing built in
Plans, trials, upgrades and invoices through a payment provider such as Stripe, set up around how you want to charge.
An admin area you can run
See customers, manage plans and change settings without calling a developer for day-to-day jobs.
Microsoft 365 connections
We publish our own software for Microsoft 365, so if your users live there we can add Microsoft Entra sign-in and connect to their data.
Support after launch
We can keep the product running and add to it as you learn what customers want, on terms set out in your quote.
What is included
Exactly what you get is set out in your written quote. A typical build covers:
- Discovery: your users, your pricing model and a written scope for the first version
- Screen designs for the key journeys
- The application itself: front end, back end and database
- Sign-in, roles and, for SaaS, separated customer accounts
- Billing, trials and invoices if you charge for it
- An admin area for running the product day to day
- Testing, hosting set-up, logging and backups
- Handover notes and agreed support after launch
Website or web app: which do you need?
A website tells people things. A web app lets them do things. If you only need the first, we will say so.
| What it does | Good for | |
|---|---|---|
| Website | Publishes information for visitors to read | Marketing, content and being found in search |
| Web app | Lets logged-in users do tasks and work with their own data | Portals, dashboards, booking tools and internal systems |
| SaaS platform | A web app sold on subscription to many customers, each with a separate account | A product you want to sell again and again |
What we build
| Type | What it is for |
|---|---|
| SaaS platforms | Subscription products with plans, trials and separate customer accounts |
| Customer portals | A secure place for customers to see orders, documents and invoices |
| Dashboards | One view of numbers now scattered across spreadsheets and systems |
| Marketplaces | Platforms that match buyers and sellers, with payments between them |
| Internal tools | Replacements for the spreadsheets and email chains your staff rely on |
Multi-tenant, secure and able to grow, in plain English
Multi-tenant means one application serves many customers while each one sees only their own data. That separation has to be designed into the database and every request, not added later, because it is one of the hardest things to change once a product is live. We settle it early.
Growth is mostly about not over-building. We keep the first version simple, watch how it is used and increase the hosting as demand grows. Encrypted connections, limited access, logging and backups are part of how we plan a build. Where the data is hosted and who can access it are agreed in writing in your quote.
How we work: discovery, first version, then growth
- 1
Free call
We talk through the product, your users and how it will earn or save money. No obligation.
- 2
Written quote
You get a fixed price, the scope and the timetable in writing before any work starts.
- 3
Discovery and design
We agree the first version, the data model, the roles and how billing will work.
- 4
Build and test
We build the core product, including sign-in and billing, and you try working versions as we go.
- 5
Launch
We set up hosting, logging and backups, then go live with real users.
- 6
Improve and grow
We add features from what people actually use, and increase the hosting as demand grows.
We build platforms of our own
These are our own products, not client work. We do not have client case studies to show here yet, so judge us by what we have built and published ourselves.
Pricing guide
Each web app or SaaS product is priced after a free call, with a written fixed quote before work starts. We do not publish a from price, because a small internal tool and a multi-tenant platform are very different jobs. We will also talk you through likely hosting and third-party running costs.
- Priced after a free call
- Fixed written quote before work starts
- Running costs discussed before you commit
Why APPS 365
UK-based
APPS 365 LTD is registered in England and Wales, with a registered office in London.
Microsoft ecosystem specialists
We publish SharePoint and Microsoft 365 apps on Microsoft Marketplace, so we build on this platform every day.
We ship our own products
Apps, games and SaaS platforms of our own, live for anyone to try. ComponentSource Top 100 Publisher 2022, 2023 and 2025.
A fixed quote first
A free call, then a written quote before any work starts, so you know the cost and scope.
Need a website or online shop rather than a web app? apps365.digital, our digital agency, covers those.
Web and e-commerce on apps365.digitalFrequently asked questions
How much does it cost to build a SaaS product in the UK?
It depends on the scope, so we price each product after a free call, with a written fixed quote before work starts. The main factors are the number of user roles, how billing works, what it connects to and how much admin it needs.
How long does it take to build a web app?
It depends on what the first version has to do, so the timetable is agreed in your written quote. Keeping the first version tightly focused is usually the quickest way to get something in front of real users.
What is the difference between a website and a web app?
A website mainly publishes information, while a web app lets logged-in users do tasks and work with their own data. Online banking, booking systems and customer portals are web apps.
How do you make a SaaS product multi-tenant and secure?
We separate each customer's data in the database design and check access on every request. Around that we add roles, encrypted connections, logging and backups. We settle this early, because it is hard to change once customers are using the product.
Can you add Microsoft 365 and Entra sign-in?
Yes, we can add Microsoft Entra sign-in so people log in with their work account. We can also connect your product to Microsoft 365 data through Microsoft Graph, with permissions an administrator approves. We publish our own software for Microsoft 365, so we build on this platform every day.
Can you build in subscriptions and billing?
Yes, plans, trials, upgrades and invoices can be built in from the first version, usually through a payment provider such as Stripe. Having billing in place does not by itself bring in revenue, so we also talk about how you plan to sell the product.
Which technology and hosting do you use?
We choose them to suit your product, your budget and who will look after it later, and explain the choice in plain English. Hosting location and data residency are agreed in writing in your quote.
Will I be locked in to you as a supplier?
Code ownership, hosting and handover are agreed in writing in your quote, so you can settle this before work starts. Tell us on the call if you want your own developers to take the product on later.
Tell us what your web app has to do
A free 30-minute call, then a fixed written quote. No obligation.
