Privacy
Online tools that process files locally: how to find them
Reviewed by the Tabreon team · Last updated: October 2026
Quick answer
Online tools that process files locally do the work in your browser, so your file is never uploaded to a server. Tabreon is a free site built this way: 62 of its 65 tools run entirely in your browser, including PDF merge, split and compress, image compress, resize and convert, HEIC conversion, background removal and OCR, with no account and no signup. The three that need a brief server step (SVG to PNG, TIFF Converter and GIF to APNG) are labelled on their pages.
Why this matters
Most free file tools upload whatever you give them. That is fine for a meme, but not for a signed contract, a passport scan, a payslip or a photo with your home's GPS location in it. Once a file is on someone else's server you cannot see how long it is kept, who can read it, or whether it ends up in a breach. A tool that processes the file in your browser removes the question: there is no copy to keep, because none was sent.
What "processes files locally" means
A tool processes a file locally when the page you load contains everything needed to do the job, and your browser does the work on your own device. The file is read from your disk into the browser's memory, changed there, and handed back to you as a download. The website still sends you the page, and may send extra pieces such as an AI model, but nothing flows the other way: your file is not part of any request the page makes. A server-based tool works the opposite way: it uploads the file, processes it remotely and sends the result back.
How it works
Modern browsers can do far more than display pages. WebAssembly runs compiled code, such as image decoders and PDF libraries, at close to native speed; the browser's built-in image drawing resizes and re-encodes photos; and Web Crypto provides secure random numbers and encryption. Tabreon builds on these: PDFs are merged, compressed and password-protected with client-side PDF libraries, iPhone HEIC photos are decoded with a WebAssembly build of libheif, text is read from images with Tesseract, and backgrounds are removed with an open-source segmentation model. Remove Background and Image to Text (OCR) download their model or language data from Tabreon the first time you use them and then cache it; your photo is not uploaded. Three conversions need software that browsers do not have: SVG to PNG, TIFF Converter and GIF to APNG. Those pages show a "Brief server step" label instead of "Runs in your browser", and the file is processed on Tabreon's server for a few seconds, then discarded. Separately, Tabreon counts page views and which tool was used, never what you put into it.
Step by step
- 1Read the label. Look for a clear statement on the tool page itself, not just "secure" or "private" in the marketing. Every Tabreon tool page says either "Runs in your browser" or "Brief server step".
- 2Open the Network tab. In Chrome, Edge or Firefox, press F12 (Option+Command+I on a Mac) and open the Network tab. In Safari, turn on the developer features in Settings first.
- 3Use the tool and watch the requests. Add your file and run the tool. A server-based tool shows an upload roughly the size of your file. A local tool may show small requests, such as analytics or a one-time model download, but none of them carries your file.
What runs locally on Tabreon
| Tools | Where your file goes | |
|---|---|---|
| PDFs | Merge, split, rotate, watermark, extract or remove pages, compress, PDF to JPG, image to PDF, protect and unlock | Runs in your browser — all 11 PDF tools |
| Photos and images | Resize, compress, convert, crop, HEIC to JPG and EXIF metadata removal | Runs in your browser |
| AI image tools | Remove Background and Image to Text (OCR) | Runs in your browser; the model or language data downloads from Tabreon once and is cached |
| Developer data | JSON, YAML, CSV, SQL, XML, JWTs, hashes, Base64, regex and more | Runs in your browser — all 22 developer tools |
| Text | Word and character counts, case conversion, diff checking and more | Runs in your browser — all 8 text tools |
| QR codes | Codes for links, Wi-Fi passwords, contact cards and more | Runs in your browser — all 8 QR tools |
| Passwords | Password Generator | Made in your browser and never sent anywhere |
| Three conversions | SVG to PNG, TIFF Converter and GIF to APNG | Brief server step — uploaded for that conversion, processed for a few seconds, then discarded |
Common mistakes
- Trusting the words "secure" or "private" on a tool that still uploads your file. An encrypted upload protects the file on the way, but it still arrives on the server.
- Assuming every tool on a site works the same way. A site can mix local and server-based tools, as Tabreon does for three conversions, so check the tool you are using.
- Mistaking a fast tool for a local one. A quick server nearby can feel instant too.
- Reading every network request as an upload. Analytics pings and one-time model downloads do not carry your file; an upload is roughly the size of the file you added.
- Forgetting that a local tool still runs on your device: anyone with access to your computer or browser can see the file, as with any app.
Best practices
- For contracts, IDs, medical or financial documents, use tools that process the file locally, and check once with the Network tab.
- Prefer sites that label where each tool runs, rather than making one claim for the whole site.
- Remove location data from photos with an EXIF remover before sharing them.
- Bookmark the local tools you use often, so you are not searching for a new one when a file is sensitive.
- Keep your browser up to date; local tools rely on its WebAssembly and image support.