Custom web app development for businesses: sell what you know as a product you own

What do businesses build a web app for?

A web app is software people log in to and do something with. A website tells visitors about your business. A web app lets a user complete a task: book, pay, upload, learn, track or approve. Businesses come to us for three kinds.

• A product to sell. You have a method, a course, a data set or a service you deliver by hand. Packaged as a subscription product, it can be sold to people you could never serve one to one.
• A platform with several kinds of user. Clients, staff and partners each log in to their own workspace, with their own permissions, on one system.
• One system in place of many subscriptions. The business runs on a stack of rented tools that do not talk to each other, and the monthly bills rise with every seat.

This page is mostly about the first two. If the build is for staff only, our page on internal tools development covers it in more depth.

Which Agentryx solutions would you be buying?

Solution	What it does	Lever it pulls
Web apps and SaaS builds	A product with accounts, roles, payments and the features your users pay for, built so it can grow.	More money per client: a new thing to sell, paid for every month.
Client portals	A login for existing clients with onboarding, files, messages and progress in one place.	More money per client: clients who can see progress have less reason to leave.
Internal tools	The admin side: the screens your team uses to run the product, approve things and see what needs attention.	Time back: the same team handles more, so the next hire can wait.

A real product often needs all three in some measure, because customers need somewhere to log in and your team needs somewhere to run it. The scope decides how much of each goes into version one. If a portal for existing clients is all you need, client portal pricing has its own bands.

What is it worth? Do the sum

The leak, as owners put it: "People keep asking me for the thing I know, and I can only sell it by the hour." Every client needs your time, so income stops where your diary does. The lever is more money per client, through a product that does not need you in the room.

The mechanism is plain. The know-how is turned into features: lessons, templates, a calculator, a tracker, a workflow. Users sign up and pay through the app. Access is switched on and off with the subscription. Your team supports users from an admin screen in place of delivering each one by hand.

Step	Example figure
Subscribers	50
Price a month	£40
Months	12
Subscription income a year	£24,000

Example figures. Swap in your own. They are made up to show the method: 50 × £40 × 12 is £24,000. They are not a result, an average or a forecast, and no software finds subscribers for you.

If the app is for your team, the sum changes shape. Count the clients one person can handle today, the number they could handle with the manual steps removed, and the yearly cost of the hire you would otherwise make.

For your own number, count three things. How many people have asked for this in the last year and would pay for it. What they would pay each month, tested by asking for money and not opinions. How many months a subscriber would stay. Bring those to the call. If you go ahead, the audit report puts a yearly figure on each problem and each fix.

What does a build like this look like?

TMMB Academy came to us with fragmented funnel and operating processes, rising software subscriptions and no single system. We built one portal with role-specific workspaces for admins, coaches, creators, sales, assistants and brands. It covers onboarding, creator performance, subscriptions and payments, course modules, calls, messages, community resources, brand deals, deliverables and operational alerts.

The implementation ran for more than 60 days. TMMB was able to take on greater capacity, improve scalability and retention, and reports generating six figures within roughly two to three months. That result is client-reported and shared with permission. We did not measure it ourselves, and your build will have its own scope and its own numbers.

When custom software is not worth it

Building is the expensive route, and it is the wrong one in several common situations.

• An off-the-shelf product already does the job. If existing software covers nine tenths of what you need at a fair monthly price, rent it. Custom software vs SaaS sets out how to compare the two.
• Nobody has paid yet. If the product idea is untested, sell it by hand first, with a document and an invoice. Build once people have paid for the manual version.
• The process keeps changing. Software fixes a way of working in place. If yours changes every month, wait until it settles.
• The sum is small. Run your own figures above. If a year of the product earns less than it costs to build and run, a spreadsheet and a shared folder are the right tools for now.

How to get from an idea to a scoped build

1. Write down the one job. One sentence on who the user is and what they can do after logging in. Our guide on how to write a software brief gives a format.
2. List the roles. Every kind of user, what each can see and what each can change.
3. Mark where a person must decide. Money, legal commitments, complaints and anything sent in your name stay with a human.
4. Cut version one down. Keep the features a user would pay for and move the rest to a later list.
5. Check who owns what. The code, the hosting, the payment account and the data should all sit in your name. See why you should own the code and accounts.
6. Book the audit. We map how the business runs and return a written report within 10 working days, with the scope and a price range.

What a custom web app costs

Scoped builds run from £5,000 to £20,000, or $10,000 to $30,000 in the US. Larger custom projects, such as multi-role platforms, are priced separately. The price moves with the number of user roles, payments, integrations with other systems, data to migrate and any AI features.

The audit is £3,000 plus VAT and is credited against the build when the build deposit is paid within 14 days of the report. Before the audit we give a range, never an exact price. Projects are 50% upfront and 50% on launch by default, and the signed scope controls. Hosting, software and AI usage are paid directly to the providers from your accounts.

Keep these prices apart from the example sum above, which uses made-up figures. Custom software cost goes through the price in detail.