Convert your Excel spreadsheet into a web app

When a spreadsheet has quietly become a system

Excel is excellent for calculating and analysing. The trouble starts when several people depend on the same workbook every day for quotes, orders, rotas, stock or jobs.

The UK has its own cautionary tale. In October 2020 Public Health England said that 15,841 positive Covid-19 cases were left out of the daily figures because some files exceeded the maximum size the system could load. Press reports traced it to the old .xls format, which holds 65,536 rows. Modern Excel holds 1,048,576 rows, so size is rarely the issue today. The real lesson is that a spreadsheet does not tell you when something has gone wrong.

These are the most common signs. If two or three sound familiar, it is worth looking at the alternative. If only one does, tidying up the workbook is often enough:

• Copies of the same workbook live on desktops, in email threads and on SharePoint, and nobody is sure which one is current.
• People wait for a colleague to close the file, or find that their changes have vanished.
• Someone retypes data between the sheet and Xero, Sage or the online shop.
• You cannot tell who changed a price or a quantity, or when.
• Customers, suppliers or engineers are emailed the workbook to fill in and send back.
• The file takes minutes to open, or links to other workbooks break whenever a folder moves.

Shared workbooks and co-authoring: why they fall short

The usual answer to the multi-user problem is to share the file. Microsoft's legacy Shared Workbook feature is still there, but Microsoft's own support page warns that it "has many limitations" and describes co-authoring, with the file stored in OneDrive or SharePoint, as its replacement.

Co-authoring lets two people type at the same time. It does not give a business process what it actually needs: each person editing only their part, data that cannot be entered wrongly, orders that move through statuses with an owner at each step, and a history of who did what. That gap is the difference between a spreadsheet and an application.

Converting Excel VBA and macros to a web application

Macros are often where the most valuable rules hide, and they are becoming harder to rely on. Since 2022, Office for Windows blocks macros in files from the internet by default and shows a Security Risk banner with no option to enable content, so a workbook emailed to a customer or downloaded from a portal may simply stop working. VBA also cannot be run or edited in Excel for the web.

Converting a spreadsheet to a web app is not copying the sheet onto a screen. It separates three things that Excel mixes together: the data, which moves to a database; the rules, meaning formulas, validations, macros and the exceptions that live in someone's head; and the screens, built for each task. Each macro is reviewed on its own:

• Macros that move data between tabs usually disappear, because the application stores everything once.
• Macros that calculate become rules on the server, tested against the figures your sheet produces today.
• Macros that produce documents become PDF quotes, delivery notes or reports generated from your template.
• Macros that run on a schedule or send emails become automated jobs and notifications.
• Macros that push data elsewhere become a proper connection: if the sheet mainly bridges two systems, what you may need is ERP integration services rather than a new app.

Power Apps, AppSheet, Airtable or bespoke: which fits

Building is not always worth it. If your process is standard for your sector, an off-the-shelf tool is usually cheaper and quicker. When that is the case, we tell you on the first call.

Low-code platforms are a reasonable choice for simple processes with few users. Check two things before committing. They are priced per user per month: in November 2026 Microsoft's UK page lists Power Apps Premium at £15.40 per user per month, paid yearly, excluding VAT. AppSheet Core is included in most paid Google Workspace plans, so if you already use Workspace it is worth a try first. And they have usage caps: Airtable limits records per base to 50,000 on Team and 125,000 on Business. As users and logic grow, the cost grows with them. If the spreadsheet has grown into a whole department's tool, the project looks more like custom internal tools development.

How the switch works without stopping the team

Before any code, we sit down with the person who knows the workbook and write down every rule: where each number comes from and what the exceptions are. Before go-live, the app and the spreadsheet are run side by side on the same data until they produce the same figures, and the team only lets go of the spreadsheet once they trust the new tool.

You see a working demo every two weeks using data from your own sheet, under one fixed price per project. The full process, including how scope changes are handled, is on our page about fixed price software development.

What drives the price and timescale

We do not quote without seeing the workbook: two similar-looking spreadsheets can hide very different amounts of work. The guide how much custom software costs explains how a price is built and gives market reference figures. The factors that weigh most:

• How many rules and exceptions need moving, especially those written down nowhere.
• The state of the data: duplicates, inconsistent formats or tabs that must be merged before migration.
• The number of macros and what each one does.
• User roles and permission rules.
• Documents to generate and how complex they are.
• External users such as customers, suppliers or engineers on their phones, who need more care with access.