Built on 20+ years
of file format expertise

Viewer.Online is the next step in a two-decade journey of making files accessible to everyone. Backed by the world's largest database of file formats.

20+
Years of experience
50M+
Users served
20K+
File formats supported
1,500+
Conversion formats

Our story

Our story began in 2000 when Tom Simondi, a software pioneer from California, launched FILExt — one of the first and most comprehensive online resources for file format information. What started as a single page of file extension descriptions quickly grew into the internet's go-to destination for anyone trying to understand, open, or work with unknown files.

FILExt gained recognition from the biggest names in technology. PC Magazine named it one of the Best 100 Undiscovered Sites. Microsoft integrated FILExt directly into Windows XP, directing millions of users to its database when they encountered unknown file types. The New York Times, Wall Street Journal, PC World, and Oracle have all recommended FILExt as a trusted resource.

Over two decades, more than 50 million users turned to FILExt to solve their file problems. The knowledge base grew into the world's largest collection of file format data — constantly reviewed, updated, and expanded by a dedicated community of contributors and experts.

From Germany to the world

Today, our team is based in Saxony-Anhalt, in the heart of Germany. From here, we develop innovative online services built on top of the world's most comprehensive file format database. Our mission is to make every file accessible, understandable, and usable — regardless of format, platform, or device.

We believe that files should never be a barrier. Whether you're a media professional working with obscure formats, a researcher examining binary data, or simply someone who received a file they can't open — we built Viewer.Online for you.

What we do

Viewer.Online takes everything we've learned from two decades of file format research and puts it into a single, fast, browser-based tool. Upload any file and we'll extract every piece of usable information: preview the content, read metadata, browse archive listings, extract hidden text from binaries, and convert between formats.

We don't just show you what a file is — we show you what's inside it.

2000
Computer Knowledge & file extensions
Tom Simondi publishes file extension reference pages on Computer Knowledge, quickly becoming one of the most popular resources on the early web.
2001
FILExt is launched
The growing collection moves to its own dedicated website — FILExt.com — becoming the largest freely accessible database of file formats and extensions.
2004
Integrated into Windows XP
Microsoft incorporates FILExt into Windows XP's file handling, directing millions of users to the database when they encounter unknown file types.
2018
New home in Germany
FILExt finds a new long-term home in Saxony-Anhalt, Germany, where development continues on the database and new online services.
2024
Convert.Guru launches
A dedicated file conversion service launches, supporting 1,500+ format conversions and making file transformation accessible to everyone.
2026
Viewer.Online goes live
The culmination of 20+ years of file format expertise — a universal file previewer that extracts, displays, and converts any file right in your browser.

Our family of services

Three products, one mission: making every file accessible.

FILExt
The world's largest database of file formats and extensions. 20+ years of curated knowledge helping users identify and understand any file type.
Convert.Guru
Fast, browser-based file conversion between 1,500+ formats. Transform images, documents, videos, and more with a single click.
Viewer.Online
Preview any file instantly. Extract metadata, browse archives, view hidden content, and convert between 20,000+ formats — all in your browser.
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