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Under the hood.

Deep-dives on how our tools actually work, the formats they operate on, and the engineering trade-offs behind a fully client-side tool hub.

privacy · engineering · product · 7 min read

Why we made every StuHub tool run in your browser

When you drop a PDF onto StuHub, nothing gets uploaded. Everything runs in the tab. Here is the engineering story behind that decision — and the features we gave up to make it work.

json · debugging · reference · 5 min read

JSON formatting gotchas — the 7 that bite most often

A parse error at line 1 column 1 can mean a hundred different things. After formatting thousands of payloads, we keep seeing the same seven problems. Here is the diagnostic list.

encoding · developer · reference · 6 min read

Base64, explained — when to use it, when it is hurting you

Base64 is one of those tools that keeps showing up — JWT payloads, CSS data URIs, email attachments, API keys. It is also one of the most over-used encodings on the web. Here is what it actually does and when you should reach for something else.

regex · developer · reference · 9 min read

The 12 most common regex patterns (and the ones you should never copy-paste)

Email, URL, phone number, date — everyone eventually writes a regex for one of these and copies it from a Stack Overflow answer that was written in 2011. Here is the short list of patterns that actually work today, and the ones that are subtly broken.

pdf · compression · technical · 7 min read

How PDF compression actually works (and why your scans barely shrink)

Why does the same compressor reduce one PDF by 70% and another by 2%? The answer is in the PDF container itself — and once you understand the three main levers, picking the right tool for any given file becomes obvious.