About Convertora

Why we built it

Most online file tools are built around a server. You upload your document, the server processes it, and you download the result. For ordinary documents this is fine — but for anything sensitive (contracts, medical records, financial statements, internal company documents) it means trusting an unfamiliar third party with full read access to your file. The file may be cached, logged, scanned for ad targeting, retained as a backup, or — if the service is compromised — leaked.

Modern browsers are powerful enough to do all of this work locally. JavaScript engines have become fast, WebAssembly opens access to compiled libraries, and the File and Blob APIs let web applications read and write files without ever touching a server. Convertora was built to take advantage of all of that: give people the same capabilities as a desktop tool, but delivered through a webpage they can open instantly.

How it works

When you open a tool page on Convertora, your browser downloads the JavaScript code for that tool from our content delivery network. Once loaded, the page is fully functional even without an internet connection. When you drop a file into the upload area, the browser reads it into memory using the native File API and hands it off to the tool's processing function — which executes inside the browser tab using JavaScript and (for some tools) WebAssembly.

The output is generated locally and offered to you as a download via a temporary blob URL. The blob URL is revoked when you close the tab. At no point does your file leave your device. There is no upload step, no progress bar tracking transfer to a remote server, no cloud worker — just your browser doing the work.

Heavy libraries (PDF.js for PDF rendering, pdf-lib for PDF modification, browser-image-compression, Tesseract.js for OCR, mammoth for Word documents, SheetJS for Excel) are bundled and loaded on demand so your initial page load stays fast.

What's available

Convertora covers four categories of tools:

• PDF tools — merge, split, compress, watermark, rotate, lock and unlock, sign, redact, repair, add page numbers, edit metadata, manage bookmarks, crop, edit, and more.
• Conversion tools — between PDF and Word, Excel, PowerPoint, HTML, Markdown, CSV, text, JSON, EPUB, RTF, ODT, SVG, and image formats.
• Image tools — resize, crop, compress, rotate, watermark, combine, color picker, pixel diff, background removal, base64 encode/decode, and HEIC conversion.
• OCR tools — extract text from images and scanned PDFs, make scans searchable, convert OCR results to Word, and extract tabular data into CSV.

Limits of browser-based processing

Doing everything in the browser has a few practical limits worth knowing about. Very large files (hundreds of megabytes, or thousands of high-resolution pages) may exhaust your browser's available memory and cause the tab to slow down or crash. Some advanced features that require server compute — for example, pixel-perfect rendering of every variant of every Word document, or AI-assisted background removal — are simplified or approximated.

For most documents in most workflows, browser-based processing is faster (no upload time) and more private (no third-party servers) than the alternatives. Where it isn't, we say so on the relevant tool page and recommend appropriate alternatives.

How Convertora is funded

Convertora is free and there is no plan to add subscriptions, file-size paywalls, watermarks, or accounts. The site is funded by Google AdSense advertisements that appear on the home page and the bottom of each tool page. Ads are served by Google and may use cookies for personalization; you can opt out via the cookie banner if you're in a region that requires consent.

Importantly, the ads have nothing to do with your files. The ad network does not see what you uploaded, what tool you used, or what you produced — because none of that data ever leaves your browser. Ad targeting uses only general signals (your IP-based country, the page URL, the keywords on the page) the same way ads on any content website do.

Open about being closed

Convertora's source code is not currently public. We rely on well-known open-source libraries (pdf-lib, PDF.js, Tesseract.js, jsPDF, mammoth, SheetJS, JSZip, and others) for the heavy lifting, and the privacy guarantee depends on the client-side-only architecture rather than on you having to audit our code line by line — your browser's developer tools can confirm that no network requests are made when processing files.

Get in touch

Have a question, a feature request, or a bug report? Send us a message via the contact form. We read everything and reply to most messages within a few business days.