Guides and how-tos
Short, practical answers to the questions that come up when you use our tools — with worked examples and the formulas behind them.
Latest guides
- Guide · ImagesHow to Reduce an Image to 100 KB Without Losing Too Much QualityA practical method for getting photos under 100 KB — or any limit — while keeping them sharp: which settings to change first, and what to do when it still won't fit.Oct 4, 2026 · 7 min read
- Guide · ImagesHow to Prepare Photos and Signatures for Online Application FormsExam, visa, passport and job portals reject photos for size, dimensions or background. A checklist and step-by-step method to get accepted on the first upload.Oct 4, 2026 · 8 min read
- Guide · ImagesJPG vs PNG vs WebP: Which Image Format Should You Use?A plain-English comparison of JPG, PNG, WebP (and AVIF) with real file sizes, so you can pick the right format for photos, logos, screenshots and websites.Oct 4, 2026 · 7 min read
- Guide · PDFHow to Merge PDF Files (Without Uploading Them Anywhere)Combine PDFs into one file on any device, privately. Plus how to fix the most common problems: wrong page order, huge files and password-protected PDFs.Oct 4, 2026 · 6 min read
- Guide · PDFHow to Convert PDF Pages to Images (JPG or PNG)Turn PDF pages into JPG or PNG images at the right resolution for screens, printing or social media — and when to choose PNG instead of JPG.Oct 4, 2026 · 6 min read
- Guide · DeveloperHow to Format JSON Correctly (and Fix the Errors That Break It)What valid JSON looks like, how to pretty-print and minify it, and how to fix the eight errors that cause most “Unexpected token” messages.Oct 4, 2026 · 8 min read
Images
- Guide · ImagesHow to Reduce an Image to 100 KB Without Losing Too Much QualityA practical method for getting photos under 100 KB — or any limit — while keeping them sharp: which settings to change first, and what to do when it still won't fit.Oct 4, 2026 · 7 min read
- Guide · ImagesHow to Prepare Photos and Signatures for Online Application FormsExam, visa, passport and job portals reject photos for size, dimensions or background. A checklist and step-by-step method to get accepted on the first upload.Oct 4, 2026 · 8 min read
- Guide · ImagesJPG vs PNG vs WebP: Which Image Format Should You Use?A plain-English comparison of JPG, PNG, WebP (and AVIF) with real file sizes, so you can pick the right format for photos, logos, screenshots and websites.Oct 4, 2026 · 7 min read
- Guide · PDFHow to Merge PDF Files (Without Uploading Them Anywhere)Combine PDFs into one file on any device, privately. Plus how to fix the most common problems: wrong page order, huge files and password-protected PDFs.Oct 4, 2026 · 6 min read
- Guide · PDFHow to Convert PDF Pages to Images (JPG or PNG)Turn PDF pages into JPG or PNG images at the right resolution for screens, printing or social media — and when to choose PNG instead of JPG.Oct 4, 2026 · 6 min read
Developer
- Guide · DeveloperHow to Format JSON Correctly (and Fix the Errors That Break It)What valid JSON looks like, how to pretty-print and minify it, and how to fix the eight errors that cause most “Unexpected token” messages.Oct 4, 2026 · 8 min read
- Guide · DeveloperHow to Convert CSV to JSON (and Back) Without Breaking Your DataConvert spreadsheet data to JSON and JSON back to CSV correctly: quoted commas, line breaks inside cells, numbers vs text, nested objects and Excel quirks.Oct 4, 2026 · 7 min read
- Guide · DeveloperWhat Is a Unix Timestamp? Epoch Time ExplainedWhat Unix time is, why it starts in 1970, how to tell seconds from milliseconds, how time zones fit in, and how to convert timestamps in common languages.Oct 4, 2026 · 6 min read
Calculators
Finance
- Guide · FinanceHow to Calculate Loan EMI (Monthly Payment) — Formula and ExamplesThe EMI formula in plain English, a worked example, why early payments are mostly interest, and how loan term and prepayments change what you pay.Oct 4, 2026 · 7 min read
- Guide · FinanceHow to Calculate Compound Interest (and How It Differs From Simple Interest)The compound interest formula with a worked example, how compounding frequency and monthly deposits change the result, and the rule of 72.Oct 4, 2026 · 7 min read
Text
- Guide · TextHow to Calculate Reading Time for an Article or SpeechThe words-per-minute numbers that actually hold up, how to estimate reading and speaking time, and how to show a “5 min read” label honestly.Oct 4, 2026 · 5 min read
- Guide · TextHow to Clean Up and Format Messy Text (From PDFs, Emails and Websites)Fix broken line breaks, double spaces, curly quotes, invisible characters and duplicate lines in text copied from PDFs, emails and web pages — in the right order.Oct 4, 2026 · 6 min read