Custom software can suit a process that existing solutions don’t support well enough. That might mean a complete platform or a small addition to your current administration. Start with the problem and investigate alternatives. This guide explains how to turn that decision into a defined assignment and a useful delivery. Our guides to software costs and code ownership cover those subjects in more depth.
What is custom software, and when does it fit your business?
Custom software is developed for a specific assignment. Its functions follow from tasks users need to complete. Examples include an internal request process, customer portal or calculation module using data from an existing package. Legal rights require a separate agreement; the word custom doesn’t settle them automatically.
First investigate why the current process isn’t working. Are people re-entering data because systems aren’t connected? Is a function missing, or are instructions unclear? Only in the second case might a new application be the direct answer. A setting, integration or different working arrangement may also help.
Put the same example to an existing package and a development partner. Show the task a member of staff needs to finish, including an unusual case. Compare how much work remains outside the system and whether your team can work that way. A package doesn’t need to copy every detail of your current process to be suitable.
Our comparison of AFAS and custom software separates configuration, an additional application and a standalone system. There’s no universal user or transaction count after which custom development becomes cheaper.
How do you describe work a developer can estimate?
Write down what someone must complete, using which data and under what conditions. ‘A dashboard with customer information’ says little. A planner assigning available staff to a request needs to know which availability is current and who may change an existing appointment.
Take a hypothetical example: a hire business wants to receive an enquiry, check availability and confirm a reservation. Its first version must also show what happens when the equipment is already reserved. Building only the screens for a successful request would miss a large part of daily work.
| Scope item | What do you record? | Question for the hire example |
|---|---|---|
| User and task | Who performs each operation? | Can customers reserve equipment or only submit enquiries? |
| Data | Origin, meaning and upkeep | Which system determines availability? |
| Permissions | Allowed viewing and changes | Who may amend a confirmed reservation? |
| Exceptions | Rejection, errors and recovery | What happens with a duplicate request? |
| Integrations | Exchanges and responsibilities | When does the reservation reach administration? |
| Acceptance | Evidence of the intended behaviour | Can staff handle ordinary and unusual requests? |
State what’s outside the first version too. Confirming a reservation may be the goal; automatically calculating a delivery route is then a separate request. A clear boundary helps you choose deliberately later instead of expanding the application without noticing.
Investigate uncertain items first. That might mean a technical trial of an integration or a discussion about available data. Investigation should answer a question that could change the approach. The number of pages in its report isn’t a useful measure of that.
How do you control budget and schedule?
Ask for a proposal tying the price to the agreed behaviour. Separate one-off development and introduction from hosting, external services and maintenance. Include your internal work: someone must check data, provide examples and make decisions.
At TopDevs, we agree a fixed price in advance for the defined assignment. That makes it important to treat new requests as new decisions. Discuss their effect on cost and timing, or which other item will have to wait. A fixed price doesn’t include every future wish.
A schedule has dependencies, such as access to an external system, a test file or agreement on a working method. Ask who provides these and what happens if they’re late. You can then distinguish development that’s behind schedule from work that can’t start because a question remains unanswered.
Judge progress through usable steps, rather than a percentage marked complete. An entered form, stored request and retrievable confirmation tell you more than isolated screen designs. Ask to see error recovery along the way. That’s part of the behaviour, not a detail to leave until after delivery.
How do design, development and acceptance work?
Use design to make decisions about the process. Can staff see what’s missing? Is the reason for rejecting a request clear? A clickable design can support that discussion, but it doesn’t prove that calculations, permissions or integrations work.
Then build and assess a connected part of the process. In the hire example, that means a request moving from receipt to review. The order depends on the risks. If the availability integration is uncertain, investigating it before designing every screen may make sense.
Acceptance means checking together whether the agreed work has been delivered usefully. Before final delivery, agree which examples you’ll use and who can approve on behalf of the business. Distinguish a defect against the agreement from a new request discovered during testing.
The supplier should also explain the technical checks. The NIST Secure Software Development Framework treats security as part of development. Ask how the team checks access permissions, vulnerable components and recovery. A test percentage or chosen framework doesn’t, by itself, prove that your main tasks work correctly.
What needs arranging for data and integrations?
Decide which system is authoritative for each set of data. If two applications can change the same customer address, establish how differences will be resolved. A technically connected integration doesn’t answer that business question.
Ask how the application handles interruptions. Can processing be retried without creating a duplicate invoice or reservation? Can someone see which requests are waiting? Our guide to connecting software explains how to make those arrangements specific.
Create a migration checking plan. Don’t only count transferred rows; check their meaning too. Do documents still belong to the right customer, and do totals match? Have staff review relevant examples. Agree when data moves and how changes made in the old system during transition will be handled.
Give test users only the access their tasks require. A successful trial using one administrator account says little about what a customer or employee can later see. Also discuss which data belongs in the test environment and who may use it.
How do you choose technology without becoming a developer?
Ask for explanations in terms of consequences for your business. Which parts depend on an external service? Who can maintain the application? What limits might matter if usage changes? A framework name doesn’t answer those questions.
A developer may suggest placing some tasks with a managed service. That can reduce work, but brings terms, charges and a dependency. Managing it yourself moves that work to your team or maintenance partner. Compare both routes against the same tasks and support requirements.
Record the choice and assumptions. A future developer can then understand why something was built that way and when to revisit it. Familiar technology still needs maintenance; a specialist component isn’t automatically unsuitable if knowledge and handover are well arranged.
For some processes, no-code rather than custom development may fit. Still ask how to export data, who maintains changes and what happens at a usage limit or price change.
What does the Mastone case illustrate?
For Mastone, we built a platform around property data. The team manages its portfolio and uses WWS rent-points calculations. Investors have a separate portal, and online brochures are generated from the same property information. Calculating, presenting and sharing therefore sit within one application.
The case illustrates building functions around a shared data model. It doesn’t establish that every property business needs its own platform or that standard products can’t offer similar functions. Investigate which parts are missing in your situation and which existing systems you want to retain.
Ask a development partner how a case relates to your assignment. Is it a similar task, integration or approach to maintaining data? The same industry is a starting point, but doesn’t prove the previous solution will fit directly.
What needs agreeing after the first delivery?
Nominate someone responsible for how the application is used. They collect user questions, decide which changes are needed and check whether the process still makes sense. Technical maintenance and responsibility for content are different tasks, even if the same party helps with both.
For support, agree availability and incident categories. Distinguish the initial response from recovery. Discuss updates, backups and who restores the system. The Dutch NCSC recommends rehearsing recovery plans and testing backups. For your application, you need to know whether a recovery trial actually succeeds and what work remains afterwards.
With TopDevs, the custom code is and remains yours. Handover also requires documentation, data and access to the services used. Record third-party components and their terms. A different maintenance team must be able to establish what’s needed to continue the work.
Where continuity still depends on a supplier, you can also investigate software escrow. That requires assessment of the specific risk and agreement. It doesn’t replace a working recovery procedure.
How do you actually get started?
Choose a process that’s causing difficulty and describe the intended outcome. Gather ordinary examples and exceptions, name the systems involved and identify who makes decisions for your team. Then investigate what existing software already covers and which part might need building.
If you’re considering custom software development, we’ll discuss that scope before estimating the assignment. You don’t need to have chosen a technical solution yet. Book a call to discuss the process and a possible first version.
