About AZ Tools
AZ Tools is a free collection of 643 browser-based utilities — calculators, converters, encoders, formatters, validators and generators — that run entirely on your own device. There are no accounts and no installs, and no server of ours ever receives what you type: every tool is a small program that executes in your browser, so your data is processed locally.
Why we built it
Many online utilities put a simple task behind a sign-up wall, or quietly send your input to a remote server to do work a browser can do on its own. AZ Tools is meant to be the opposite: open the page, get the result, close the tab. Each tool does one job well, loads fast, works on phones and desktops alike, and is available in six languages — English, Korean, Japanese, Spanish, Portuguese and Chinese.
We never receive your input
This is the core promise of the site. Whether you are formatting JSON, hashing a file, generating a QR code or converting units, the computation happens in client-side code that ships with the page. Files you choose are read in the browser, not transmitted. There is no backend that receives your content, which means there is nothing for us to store, sell or leak. You can verify this yourself: open your browser’s network panel while you use a tool, and you will see that no request to this site carries your input. The few tools where your browser contacts another site are listed in the privacy policy.
How the tools work
Each tool is a self-contained widget written in TypeScript and rendered as an interactive island on an otherwise static page. The real work — parsing, encoding, arbitrary-precision math, image processing on a canvas — runs on your machine using standard web APIs. Because the pages are static and the logic is local, most tools keep working on a slow or dropped connection once the page has loaded; the few that rely on a large library or data file download it from this site the first time they need it.
How we check accuracy
Correctness matters for tools people rely on, so non-trivial algorithms are validated against published reference vectors and round-trip tests before a tool ships — for example check digits against known-valid barcodes, hashes against official test values, and conversions against exact unit definitions. Every tool is also driven in a real browser by automated tests to confirm it actually loads and produces the expected output, not merely that it builds. When we get something wrong, we fix it and say so.
What the checks cover
The test suite runs more than 14,000 automated checks across the site, and the rule behind all of them is that the expected answer must come from outside our own code: a published test vector, an independent reference library, an official worked example or a formula written out from its specification. Generated files are read back rather than eyeballed, so a PDF is parsed, an image is sampled pixel by pixel and an audio file has its header decoded. Every tool page is also loaded at phone width to catch layouts that scroll sideways, and the explanatory text on each page is reviewed against what the tool actually does, so a description cannot promise a feature the code lacks. We do not publish calculators whose result depends on one country's tax or benefit rules, because a rate that changes overnight would make such a tool quietly wrong.
Who runs AZ Tools
AZ Tools is an independent project maintained by a small team that builds and uses these utilities every day. It is funded by unobtrusive advertising so the tools can stay free; the ads never change how a tool behaves or what it does with your input. If you find a bug, a wrong result, or a tool that could be clearer, we genuinely want to hear about it.
Contact & feedback
Questions, corrections and suggestions are always welcome at the address below. We read every message and use it to prioritise fixes and decide which tools to build next.
aztools.service@gmail.com