Learn it. Make it. Done.
Clear explanations for the work behind the tools. No long detours.
Protect PDF: a practical guide
Encrypt a PDF with an AES-256 opening password.
Create and test a QR code for a printed link
Generate a PNG QR code with a known destination, choose size and correction settings, and verify the final printed version.
Test JavaScript regex captures with a bounded example
Enter a delimiter-free JavaScript pattern, inspect capture groups and indexes, and understand the worker timeout and match cap.
Deduplicate a line list while keeping its first entries
Remove repeated whole lines, decide whether case matters, and understand how spaces and blank lines affect the result.
Clean pasted spacing while retaining paragraph breaks
Collapse repeated spaces and tabs, trim line edges, and understand which formatting this plain-text cleanup intentionally removes.
Repair PDF: a practical guide
Attempt to rebuild a PDF’s damaged structure.
Generate a small robots.txt file with explicit disallowed paths
Create one user-agent group and a sitemap reference while distinguishing crawl guidance from access protection.
Convert gross pay using explicit paid weeks and working hours
Translate hourly, weekly, monthly, and annual gross amounts without confusing equivalents with take-home pay.
Solve a savings target for an assumed month-end contribution
Estimate equal monthly additions from a target, current balance, horizon, and fixed nominal return assumption.