About OnDevice

OnDevice is a small set of free everyday tools — converting images, editing PDFs, compressing files, doing quick AI tasks like rewriting a paragraph or removing a background, and a handful of calculators and text utilities. New ones get added when we find a job that people keep asking for.

What makes it different is where the work happens. Every tool runs inside your own browser tab, on your own computer. When you drop a PDF onto the page or paste in some text, nothing is sent to us. The page does the work right where it loaded, and the result appears in front of you. You can open your browser’s developer tools, watch the network panel while you use any tool, and confirm that no file ever leaves your machine.

Why we built it

Most free online tools work by asking you to upload your file. The site receives it, processes it on a server somewhere, and hands you back the result. That arrangement quietly puts a lot of trust in a stranger. A contract, a passport scan, a tax document, a private photo — every one of those gets copied onto a machine you don’t own, handled by software you can’t see, and kept for as long as the operator decides to keep it. The privacy policy might say one thing. The reality might be another. You usually have no way to check.

We started OnDevice because that gap between “trust us” and “you can verify it” bothered us. The browser is already a capable little computer. A modern laptop or phone can split a PDF, shrink a photo, or run a small AI model on its own, without any help from a server. So that’s how we built every tool here. Your file goes from your hard drive into the page, and back out again as a result you can save. The middle step never goes through us.

It also turns out to be pleasant in other ways. The tools usually feel instant because nothing has to travel. Big files don’t struggle against your upload speed. And once a tool has loaded once, it keeps working even if your internet drops.

What “runs in your browser” really means

When you visit a tool page, your browser downloads the page along with the small program that does the work. After that point, the program lives in your tab. You hand it a file by dropping or selecting it, and it reads the file directly from your computer — the same way a desktop app would. The result is built right there in the tab, and your browser offers it back to you as a download.

A good way to picture it: the first time you load a tool, you’re downloading the tool itself, like installing an app. From then on, the tool is yours. Put your laptop in airplane mode, open the same tool again, and it still works. Try it — turn off your wifi after the page has loaded, run the tool, and you’ll see the result come out exactly the same. That isn’t a clever trick. It’s just how the site is built.

The AI tools work the same way. The model itself is downloaded into your browser the first time you use it, and it runs there from then on. Nothing you type at the AI is sent to OpenAI, Anthropic, or any other provider, because we don’t talk to one. The model is small, the answers are short, and they happen on your hardware.

Who runs it

OnDevice is built and maintained by Hannah Ren, a software engineer based in the United States. The site launched in April 2026 as a side project after one too many frustrating experiences uploading sensitive paperwork to free tool sites of unclear provenance.

It is a one-person operation. Hannah picks the tools, writes the code, answers the email, and pays the bills. There is no investor breathing down anyone’s neck to monetise your data, because there is no investor. If you write to us, you are writing to her.

How we make money

OnDevice is funded by two things: a small Pro tier and ads on the free tier. Pro is optional. It removes the ads, lifts the daily AI usage cap, and helps keep the rest of the site free for everyone who doesn’t want to pay. We’d rather charge a few people a little than make the free tier feel cheap.

Three third-party services do load on this site, and we want to be plain about them. Clerk handles sign-in for Pro, and only loads on the pages where signing in matters. PostHog records anonymous usage analytics — which tool was used, roughly when — without cookies, without storing your IP address, and without ever being joined to your files (your files never reach us, so the join would be impossible anyway). Google AdSense serves the ads on the free tier. All three are blockable by any standard ad or tracker blocker; the tools themselves keep working if you block them. We won’t claim “zero tracking,” because that wouldn’t be honest. We will say: anonymous, blockable, and never tied to the contents of what you process.

Get in touch

Email is the best way to reach us at hello@ondevice.tools. Bug reports, feature requests, broken tools, or just hello — all welcome. We aim to reply within two business days. For billing or security questions, see the addresses on our contact page.

Last updated: May 2026