Toolsera guides

Short, practical guides that explain how things work and link to the tool that does the job.

• How to Format and Validate JSON (and Fix the Most Common Errors)

  Learn what makes JSON valid, how to format it so it is readable, and how to fix the errors that break parsers: trailing commas, single quotes, comments and more.

  By Amey S · Updated 8 November 2026

• How Is EMI Calculated? The Loan EMI Formula Explained

  Understand the EMI formula step by step, with worked examples for a home loan, and see how amount, interest rate and tenure change your monthly instalment.

  By Amey S · Updated 8 November 2026

• How to Make a QR Code That Scans Every Time (Wi-Fi, UPI, Contact Card)

  A practical guide to making QR codes for links, Wi-Fi, UPI payments and contact cards, with advice on size, colours, error correction and testing before you print.

  By Amey S · Updated 8 November 2026

• How to Reduce Image and PDF File Size for Uploads and Email

  Practical ways to shrink photos, scans and PDFs so they fit upload limits like 100 KB or 2 MB, without making them unreadable. Includes merging and splitting tips.

  By Amey S · Updated 8 November 2026

• How to Calculate Percentages: Of, Change, Increase and Decrease

  Simple formulas and worked examples for the five percentage questions people ask most: percent of a number, what percent, percentage change, increase and decrease.

  By Amey S · Updated 8 November 2026