About NiftyKit and Stuart Mathieson

Hello, I’m Stuart

I’m Stuart Mathieson, an independent freelance web developer based in Scotland. I build websites and web apps for small businesses and other clients, and you can see some of that work at stuartsm.com.

NiftyKit is my own project. I design, write, code and test every tool and every guide on it. There’s no team and no company behind it, so if something here is wrong, it’s my mistake to fix, and I’d like to hear about it.

Why I built it

Building and looking after websites involves dozens of small jobs that have nothing to do with the interesting part: tidying an API response, shrinking a client’s photos, checking a certificate before launch, making a favicon, comparing two versions of some copy, sending an invoice at the end of the month.

There are online tools for all of those, but I kept running into the same problems. Pages so crowded with adverts that the tool was hard to find. “Download” buttons that weren’t the download. And the one that bothered me most: many tools quietly send whatever you paste to their own server. When the thing you’re pasting is a client’s customer data, a live login token or an unpublished photo, that isn’t a small detail.

So I started building my own, with one firm rule: everything runs in your browser. Your text and files are processed on your own device and never uploaded. NiftyKit is that collection, tidied up and made public. There are currently 37 tools and 6 guides.

What makes it different

I also run SmartCalc Hub, a site of calculators for money, tax, study and everyday numbers, with guides to things like Scottish income tax and student loans. That site is for anyone with a number to work out.

NiftyKit is the workbench side of what I do. It’s for people who make and run websites: developers, designers, freelancers and small business owners who look after their own site. A few simple tools, such as a JSON formatter or a password generator, appear on both sites because people look for them in both places. On NiftyKit they go further, and they sit alongside tools you won’t find on SmartCalc Hub: certificate and token decoders, image compression and metadata removal, favicon and colour palette generators, PDF and invoice tools.

The guides are the other difference. Each tool does one job, and the guides show how they fit together in real work, such as launching a small business website, getting images and colours right, invoicing clients properly, or debugging data without pasting secrets into the wrong website.

How I build and test the tools

Your input stays on your device. My code never sends what you type anywhere, and an automated test checks every tool to make sure no request ever contains it. You can check this yourself in your browser’s developer tools: open the Network tab and use a tool. The tools also work offline once a page has loaded. The privacy policy has the details.
Every tool is tested. The logic behind each tool has its own automated tests, including empty, invalid, very large and non-English input. Every page is also tested in Chrome, Firefox and Safari, on desktop and mobile.
Accessible by default. Each page is checked against the WCAG 2.2 AA accessibility guidelines, works with a keyboard and screen readers, and never relies on colour alone.
Honest about limits. Every tool page explains what the tool does, how it works and where its limits are, so you know when to trust a result and when to double-check it.
Few dependencies. Most of the code is my own. Where I use an open-source library, such as for PDFs or QR codes, I choose it carefully and test its output independently.

What NiftyKit isn’t

The tools are general-purpose helpers, not professional advice. The invoice generator makes a tidy PDF, but I’m a developer, not an accountant: if you’re unsure what your business needs to charge or record, ask someone qualified. The same goes for anything security-critical. The tools help you inspect and understand things, but they don’t replace a proper security review.

How the site is paid for

NiftyKit is free, with no account and no paywall. Adverts from Google AdSense pay for the hosting and the time it takes to build and maintain it. They will never hide the tools or pretend to be a download button, and my code never passes what you type into a tool to them. In the UK and Europe you choose whether ads can be personalised, and you can change your mind with the privacy and cookie settings. Nobody pays to be featured or recommended in a guide.

Get in touch

I would rather build a few excellent tools than hundreds of mediocre ones. If there’s a small job you do often, a tool that could be better, or a mistake in a guide, email me at [email protected] or see the contact page. I read every message, and fixes go up as quickly as I can make them.