Learn by doing
Solve a file problem with a small practice example
Choose a concrete problem, compare the expected result, then use the same workflow with your own files.
Keep leading zeros in CSV identifiers and ZIP codes
An ID such as 00123 is text, even when it contains only digits. Choose an export for Excel or a plain-text importer, then check the actual saved values.
Merge PDF files in the order you need, without uploads
Combine a two-page main document and a one-page appendix into one PDF. Use the file-order controls and check the result before sharing it.
Convert a JSON array to CSV for Excel without uploading it
Turn a small API-style export into spreadsheet columns. Check how fields line up and how identifiers survive the import before processing your own records.
Fix a semicolon CSV for Excel without uploading it
Turn a small European-style CSV export into an Excel-friendly copy. Use the practice file first, then repeat the same checks with your own data.
Extract pages from a PDF without uploading it
Create separate PDFs for pages 1–3, page 4, and pages 5–8. The practice document contains only numbered demonstration pages.
Find a trailing comma in JSON and format the corrected data
Use a short invalid object to practice reading a JSON parse error. Then correct the syntax, sort the keys, and save valid JSON.