About OnlineToolHubs
OnlineToolHubs is a collection of 275 free, single-purpose web tools across 13 categories — calculators, converters, developer utilities, PDF tools and reference lookups. There is no account system, no paid tier and no usage limit.
Who runs it
The site is built and maintained by one independent developer. It is not a company, it has no editorial team, and there is no staff of experts behind it — which is worth saying plainly, because a lot of sites in this category imply otherwise. What that means in practice is that the pages are not written by subject specialists, so every calculation names the published formula it uses and cites where that formula came from, and every data-backed page names its source. You are meant to be able to check the work rather than trust the author.
If something here is wrong, the fastest way to get it fixed is to say so — see the contact page. Corrections get made.
How the tools work
They fall into two groups, and the distinction matters for your privacy:
- 254 run entirely in your browser. Calculators, converters, text tools, image tools, PDF tools and the encoders and decoders all execute locally in JavaScript. The file you open or the text you paste is never transmitted, because there is no server to transmit it to — the whole site is a set of static files.
- 21 query a public API. Weather, air quality, DNS records, currency rates and similar lookups need a live network request to answer at all. Each of those pages names the specific service it calls, and says what happens when that service is unavailable or rate-limits.
Where the data comes from
Forecasts come from Open-Meteo, which aggregates output from national meteorological agencies including NOAA, ECMWF, DWD and the UK Met Office. Country data is a bundled snapshot from an open, version-controlled dataset combined with World Bank population figures. MAC address vendors come from the IEEE registry. Where a page quotes a standard, a formula or a regulatory figure, it links to the primary document rather than to another website that repeated it.
Bundling data locally where possible is deliberate. Several free APIs that tools like these commonly relied on have shut down without notice, and a page whose answer disappears with them is worse than one built on a snapshot with a stated date.
What gets published, and what does not
Not every tool that has been built is live. A tool is only published once it has reference content whose numbers have been individually verified, and several have been held back or removed entirely — including ones whose underlying data source turned out to be unverified trivia, placeholder content, or in one case a security checker that returned the same confident result regardless of what it was given. A tool that produces a plausible answer without measuring anything is worse than no tool.
Privacy
No account, no registration, no location permission requested — including on the weather tools, which take a city name you type. For the browser-based tools we never receive your data at all. Full detail, including what advertising involves, is in the privacy policy.
How the site is funded
Advertising, through Google AdSense. That is the entire business model — there is nothing to upsell, no data being sold, and no premium tier the free tools are designed to push you toward. Ads are what keep the tools free and unlimited.
Contact
Corrections, bug reports and tool suggestions are all welcome at contact@onlinetoolhubs.com, or via the contact page.