How Toolula works without uploads

In plain words

A normal online converter works like a copy shop: you hand over your file, someone else's computer processes it, and you get the result back. Toolula works like a tool you borrow: the page brings the program to your computer, and your computer does the work.

That is possible because modern browsers can run demanding programs — PDF engines, text recognition, AI models — at close to native speed with WebAssembly. Once a tool is loaded, it does not need a server to process your file.

What runs in your browser

When you open a tool, the page loads the code it needs. PDFs are read with PDF.js and written with pdf-lib; text recognition uses Tesseract; Privacy Shield uses MediaPipe and ONNX Runtime; background removal uses the open BiRefNet and MODNet models; translation uses the browser's built-in translator or Mozilla's Bergamot engine; video and audio use Mediabunny. Most of these are WebAssembly modules and run in Web Workers, so the page stays responsive.

Your file is opened through the browser's File API, kept in memory, and the result is created as a download in the same tab. The files listed in History are stored in your browser (IndexedDB) on this device only.

What is downloaded, and from where

Program files are loaded the first time you use a tool and then come from your browser's cache.

toolula.com

The pages and app code, and every tool runtime: PDF fonts and character maps, the OCR engine with its language data (21 languages), the face and licence-plate detectors, the background-removal models, the code editor.

huggingface.co (Hugging Face Inc.)

Only when you translate in a browser without a built-in translator: Mozilla's translation models, checked against Mozilla's published SHA-256 before use.

These downloads contain program files only. Your files are never part of them.

What never leaves your device

• The files you open — PDFs, images, scans, videos, invoices, résumés.
• Their content: recognised text, extracted tables, translated text, invoice data and customer lists.
• The results you create and the files kept in History.
• Signing certificates (.p12/.pfx) and their passwords; your signature images.

When data does leave your device

• Time-stamp for certificate signatures: if the time-stamp option is on (the default), only a SHA-256 hash of the signature value is sent to the RFC 3161 time-stamp relay rfc3161.ai.moda. The document is not sent. You can switch the time-stamp off.
• Toolula Pro licence: activating or re-checking a licence sends the licence key to the licence provider Polar.
• Sign-in and AI assistants (MCP): signing in, or connecting an AI assistant, sends your sign-in data to Lovable Cloud; text the assistant sends to Toolula's MCP tools is processed on the server.
• Advertising and statistics: like most free websites, Toolula shows Google ads, and Google Analytics runs only after you agree. These scripts see that you visited a page; Toolula's code does not pass them your files or their content.

Details and legal bases are in the privacy policy.

Check it yourself

1. Open a tool, for example Edit PDF, in Chrome, Edge or Firefox.
2. Open the developer tools: F12, or Ctrl+Shift+I (Cmd+Option+I on a Mac), and select the Network tab.
3. Tick “Preserve log” and click the clear button so the list is empty.
4. Now open a file in the tool and work with it.
5. Look at the requests: the list shows downloads of program files (from toolula.com and its /vendor folder) and the ad scripts — but no request that sends your file. Sort by the Method column: Toolula itself makes no POST or PUT request while you work. The only exception is the time-stamp request when you sign with a certificate, and its size is a few hundred bytes, not your document.
6. To see it even more clearly, switch the Network tab to “Offline” after the tool has loaded and process another file. It still works.

Works offline

Toolula installs a service worker. Once a tool has been used, its code and program files stay in the browser cache, so the tool keeps working without an internet connection — on a train, in a plane or behind a strict company firewall. You can also install Toolula as an app from the browser menu. Translation works offline once its language pack has been downloaded.

Standards and formats

What the tools produce, in the words we can back up with the code. None of these are certifications.

XRechnung 3.0 (UBL)

E-invoices following EN 16931 with the XRechnung 3.0 specification (Peppol BIS Billing 3.0 profile), including Leitweg-ID for public buyers.

ZUGFeRD 2.x / Factur-X 1.0, profile EN 16931

Invoice PDF with the CII XML embedded as factur-x.xml, as PDF/A-3b.

E-invoice check

XRechnung, ZUGFeRD and Factur-X files (UBL and CII) are checked in the browser against a subset of the EN 16931 and XRechnung 3.0 business rules. It does not replace the official KoSIT validator.

PDF/A-2b

Converting existing PDFs for archiving; anything that cannot be made conformant is reported instead of hidden.

PAdES B-B / B-T

Digital signatures with your own certificate (ETSI.CAdES.detached), with an optional RFC 3161 time-stamp. These are advanced electronic signatures, not qualified electronic signatures (QES).

Open-source software

Toolula is built on these open-source projects. Thank you to their authors.

PDF.js (Mozilla)

Reading and displaying PDFs · Apache-2.0

pdf-lib, @cantoo/pdf-lib

Writing and changing PDFs · MIT

fontkit

Embedding fonts in PDFs · MIT

HarfBuzz (harfbuzzjs)

Font subsetting · MIT

Tesseract.js / Tesseract OCR

Text recognition (OCR) · Apache-2.0

MediaPipe Tasks (Google)

Face detection in Privacy Shield · Apache-2.0

ONNX Runtime Web (Microsoft)

Licence-plate detection and background removal · MIT

BiRefNet (Peng Zheng et al.)

Background removal, any subject · MIT

IS-Net / DIS (Xuebin Qin et al.)

Background removal, any subject, on phones · Apache-2.0

MODNet (Zhanghan Ke et al.)

Background removal, portraits · Apache-2.0

OpenCV.js

Scan edge detection and straightening · Apache-2.0

Bergamot / Firefox Translations (Mozilla)

Translation in the page · MPL-2.0

Mediabunny

Video and audio conversion · MPL-2.0

ZXing

Reading QR codes and barcodes · Apache-2.0

Monaco Editor (Microsoft)

Code editor of the developer tools · MIT

SheetJS (xlsx)

Excel export · Apache-2.0

mammoth, docx

Word import and export · BSD-2-Clause, MIT

JSZip

ZIP files · MIT

Noto, Arimo, Carlito, Caladea, Tinos, Cousine, Inter Tight, Open Sans, Lora, Roboto, Lato, Merriweather, EB Garamond, Caveat, Dancing Script, Geist

Fonts for edited PDFs, invoices and résumés · OFL-1.1