Guides
Plain-English guides to PDFs, images, passwords, UUIDs, timestamps and loans, each linked to a free tool that runs in your browser.
- How to Check an Online Tool Doesn't Upload Your Files
Many sites claim your files stay private. Here is how to verify it yourself in two minutes with your browser's developer tools.
- How to Compress a PDF Without Uploading It
Why PDFs get big, the two ways to shrink them, how to hit a size limit like 200 KB or 1 MB, and what you give up.
- JPG vs PNG vs WebP: Which Image Format Should You Use?
A practical guide to choosing between JPG, PNG, WebP and AVIF, with a simple rule for each type of image.
- UUID v4 vs v7: Which Should You Use for Database Keys?
What changed in UUID versions 6 and 7, why random UUIDs can slow down a database, and when v4, v5 or v7 is the right choice.
- Base64 Is Not Encryption: What It Is and When to Use It
Base64 turns bytes into safe text. It does not protect anything. Here is what it is for, how it works and why it makes data bigger.
- Unix Timestamps Explained: Seconds to Nanoseconds
What a Unix timestamp is, how to tell seconds from milliseconds or nanoseconds by length, and common pitfalls.
- How Long Should a Password Be?
Why length and randomness beat clever substitutions, how many bits of strength different passwords have, and what to do about reuse.
- How Is EMI Calculated? Formula and Example
The reducing-balance EMI formula step by step, a worked example, and why early payments are mostly interest.