We are two friends building Pageonaut, a collection of 126 free browser tools (converters, calculators, PDF and image utilities, dev helpers). Early on we committed to one constraint: everything runs client-side. No file uploads, no accounts, no server-side processing.
That one decision shaped the whole architecture, and it broke things in ways I did not expect. Here are the lessons, including the one where our server filled up with 419 GB of cache and took the site down twice.
Why client-side only
Every time I needed a quick converter, the top search results wanted me to upload my file to their server, create an account, or pay to remove a watermark. For work that a browser can trivially do locally.
So the rule became: drop a file into one of our converters and it never leaves your device. You can watch the network tab while using it. This is great for privacy and trust, and it has a nice side effect: our server does almost nothing per user, so hosting stays cheap even if a tool gets popular.
