About Office Utilities
106 office tools that run entirely inside your browser. No server does the work, because there is no server to do it.
The idea
Every online converter asks for the same thing: upload your document, trust us with it, wait in a queue. For a holiday photo that is fine. For a signed contract, an unreleased set of results or a payroll spreadsheet, it is a real risk that most people take because the alternative is installing software.
Modern browsers no longer make that trade necessary. They can parse ZIP containers, decode and re-encode images, rasterise PDFs, run cryptographic hashes and lay out documents — all natively and all locally. Office Utilities is built entirely on those capabilities.
How it works
The app is a static site: HTML, CSS, JavaScript and WebAssembly, served from a CDN and cached by a service worker. When you choose a file, it is read with the File API into memory in your tab, processed there, and handed back to you as a Blob that your browser saves to disk.
Two of the heaviest jobs run off the main thread in Web Workers: PDF.js does all its parsing and rendering in its own worker, and file hashing runs in another. The rest — spreadsheets, Word, PowerPoint, images and PDF writing — is done on the main thread, so a very large file can make the tab unresponsive while it works. It is doing the work rather than waiting on a server, but the honest version is that the interface can stall, not that it never does.
At no point is there a network request carrying your data — you can verify this yourself by opening your browser's network panel while you work.
What it is built with
- Angular 20 with standalone components and signals
- Server-side rendering at build time, so every tool page is real HTML for crawlers
- PDF.js for rendering and pdf-lib for writing PDFs, including AES encryption
- SheetJS for spreadsheets, Mammoth and docx for Word
- JSZip to read the OpenXML containers behind DOCX, XLSX and PPTX
- Mermaid for text-driven diagrams, plus a custom SVG canvas for the studio
- the Web Crypto API for hashing, in a Web Worker so a large file does not lock the page
Honest limitations
Doing everything locally has trade-offs, and it is better to name them than to pretend otherwise:
- Very large files are bounded by the memory your browser tab is allowed to use, typically a few gigabytes on desktop and much less on mobile.
- Word and PowerPoint layout is reconstructed from the OpenXML, not rendered by Microsoft's own engine, so intricate layouts can reflow. Ordinary business documents convert well.
- Watermarks that were flattened into a page image cannot be removed losslessly — nothing can do that, on any device.
- There is no OCR of scanned pages in this release, so text extraction needs a text layer.
Who makes this
Office Utilities is built and maintained by Priyabrata Saha, a software engineer. It started as a personal objection to uploading a signed contract to a stranger's server in order to rotate one page of it, and it is still a one-person project rather than a company.
That means there is a person accountable for what these tools do and what they claim. The code is public under AGPL-3.0, so the privacy claim on this site is something you can check rather than something you have to believe. Corrections and bug reports are welcome at priyabrata.saha@office-utilities.org, and writing about the work lives on Medium.
Cost, and how it is paid for
The tools are free and there is nothing to sign up for. The site is paid for by advertising from Google AdSense and by donations. Ads are served by Google and it sets its own cookies to do so; it never receives your documents, because your documents are processed on your own device and their contents are never sent anywhere. See the privacy page for exactly what is stored on your device and how to clear it.