About johnmcm.com

Who runs it

I'm John, a software developer in the United States, on Eastern time. I have been building software for 25 years, most of it business systems and web applications. I started johnmcm.com in June 2026. It is a one-person site: I build and run it myself.

Why it exists

Sooner or later everyone gets a file they cannot open: an Outlook mailbox, a Publisher document, a Project plan, a drawing from a program they do not own. The usual choices are to buy the program, install something you are not sure about, or upload the file to a website you know nothing about. This site is another way: free tools that open, convert or repair a file without the program, and without the file leaving your device.

How the tools work

Nearly every tool runs in your browser. The page reads your file on your own computer or phone, does the work there and gives you the result; the file is not uploaded. A few are exceptions: ZIP to Text sends the archive to this site's server, and the Citation Generator looks web addresses up there. Private by design explains how it works, how to check it for yourself, and lists every exception.

How it is built and checked

I build the site with the help of AI coding tools. I decide what to build, review what is written, and test every tool with real files before it goes live. When something is wrong, I fix it; What's new lists the changes, including the ones visitors asked for.

What happens to feedback

I read every message sent through the feedback form, and make an honest attempt to address each one. Changes made because someone asked for them are listed on What's new. A few of them:

• Snapchat Memories no longer builds up memory on long exports in Firefox, and has a Gentle mode that is easier on the graphics card.
• The Access Viewer can hand an SQLite file straight to the SQL Playground.
• Video Repair now says why a working video cannot be used as the pattern file.

Ask for a tool

If a file will not open here, tell me through the feedback form or at webmaster@johnmcm.com, and I will look at adding it. Open a file also counts the file types it cannot open. That is how LaTeX's .tex and .aux files and Adobe's .acsm ebook tickets came to be covered.

Contact

For a problem with a tool or an idea for a new one, use the feedback form: the button below, or the one under every tool. Messages come to me and are never shown publicly. For anything else, email webmaster@johnmcm.com.

Keeping it free

There are no ads, no accounts and no paid tier. If a tool saved you time, the Donate button at the top of the page (through Ko-fi) helps with the running costs; nothing is held back from anyone who does not give. If you are looking for a developer, see Hire me.