Free Tool Guides & Tutorials
Practical, step-by-step guides for using our most popular free online tools. No jargon, no fluff — just clear instructions and expert tips.
PDF guides
How to Compress a PDF File Online (Free, No Software)
Reduce PDF file size instantly using free online tools — no software download, no email required.
Read guideHow to Merge PDF Files Free on Any Device
Learn how to merge PDF files free in your browser — combine, reorder, and organize pages on any device with no uploads and total privacy.
Read guidePDF to JPG: Convert PDF Pages to Images Free
Convert PDF pages to JPG images and turn images back into PDFs free in your browser — high quality output, no uploads, complete privacy.
Read guideHow to Sign a PDF Online Free in Your Browser
Sign a PDF online free by drawing, typing, or uploading your signature — all in your browser with no uploads, plus e-signature basics.
Read guideImages guides
How to Resize Images Online for Free
Resize, compress, and convert images in seconds — directly in your browser without uploading to a server.
Read guideConvert HEIC to JPG: iPhone Photos Made Easy
Learn why iPhone photos are HEIC and how to convert them to JPG free in your browser — fast, private, and working on any device.
Read guideWebP vs JPG vs PNG: Which Format Should You Use?
WebP vs JPG vs PNG explained: which image format to use for photos, graphics, and transparency, plus how to convert between them free.
Read guideHow to Remove an Image Background Free Online
Remove an image background free in your browser for product photos and profile pictures — automatic cutouts with no uploads or sign-up.
Read guideHow to Take a Passport Photo at Home
Take a compliant passport photo at home free using your browser — learn size rules, background tips, and common reasons photos get rejected.
Read guideQR codes guides
How to Generate a QR Code for Free
Create QR codes for URLs, Wi-Fi, contacts, and text in seconds — no sign-up, no watermarks.
Read guideWiFi QR Code Guide: Share Your Network Instantly
How WiFi QR codes work, the WIFI: string format phones read, printing tips for guest networks, and the security points to consider before you share.
Read guideSecurity guides
Developer guides
How to Format and Validate JSON Online
Format, validate, and minify JSON in seconds with a free online JSON formatter. Spot syntax errors instantly and convert clean JSON to other formats.
Read guideHow to Convert JSON to CSV (Nested Objects, Arrays)
Turn JSON arrays into clean CSV files: flatten nested objects, handle arrays, and avoid the UTF-8 BOM and separator gotchas that break Excel imports.
Read guideUnderstanding JWT Tokens: Structure and Pitfalls
A clear guide to JSON Web Tokens: the header.payload.signature structure, base64url encoding, standard claims, and the security mistakes that bite teams.
Read guideHash Functions Explained: MD5 vs SHA-1 vs SHA-256
What hashing is, why collisions matter, why MD5 and SHA-1 are broken for security but fine for checksums, and how salting protects stored passwords.
Read guideCron Expressions Guide: Syntax and Common Patterns
Learn cron syntax field by field, master the special characters, copy common scheduling patterns, and avoid the timezone mistakes that misfire jobs.
Read guideHealth guides
How to Calculate Your BMI Online — Complete Guide
Calculate your Body Mass Index (BMI) for free and understand what the results mean for your health.
Read guideUnderstanding BMR, TDEE and Daily Calorie Needs
Learn the difference between BMR and TDEE, the Mifflin-St Jeor equation, activity multipliers, and how to set a safe calorie target for your goals.
Read guideHeart Rate Zone Training: A Complete Guide
Understand the five heart rate zones, how to estimate your maximum heart rate, the limits of the 220-minus-age formula, and the value of zone 2.
Read guideHow Pregnancy Due Dates Are Calculated
Learn how due dates are estimated using Naegele’s rule, the trimester timeline, and why few babies actually arrive exactly on their due date.
Read guideVideo & Audio guides
How to Make a GIF From a Video Clip Free
Make a GIF from any video clip free in your browser — control frame rate, size, and dimensions, with all processing done on your device.
Read guideHow to Compress a Video for Email Attachments
Compress a video to fit email attachment limits like Gmail's 25 MB free in your browser — adjust resolution and bitrate with no uploads.
Read guideHow to Extract Audio (MP3) From a Video File
Extract audio from any video and save it as MP3 free in your browser — pull music, podcasts, or lectures from video with no uploads.
Read guideFinance guides
Understanding Compound Interest: Formula and Examples
Learn how compound interest works, the formula behind it, a verified worked example, why compounding frequency matters, and the rule of 72.
Read guideHow Much House Can You Afford? An Affordability Guide
Understand the 28/36 rule, debt-to-income ratios, down payments, and PMI so you can estimate a realistic home price before you talk to a lender.
Read guideDebt Payoff Strategies: Snowball vs Avalanche
Compare the debt snowball and avalanche methods, understand the minimum-payment trap, and learn the basics of consolidation to pay off debt faster.
Read guideA Beginner’s Guide to 401(k) Retirement Savings
Understand 401(k) basics: the employer match, traditional vs Roth contributions, why limits change yearly, and how decades of compounding add up.
Read guideCalculators guides
Date & Time guides
How to Schedule Meetings Across Time Zones
A practical guide to scheduling across time zones: UTC basics, daylight saving pitfalls, and finding fair overlap windows for global teams.
Read guideBusiness Days and Deadlines: A Practical Guide
Learn how business-day math works for deadlines: counting weekends, why holidays vary by country, and common contract deadline conventions.
Read guideNetwork guides
DNS Records Explained: A, CNAME, MX, TXT and More
Understand A, AAAA, CNAME, MX, TXT, NS, SOA and CAA records, what TTL really controls, and why DNS propagation is mostly a caching myth.
Read guideEmail Authentication: SPF, DKIM and DMARC Explained
How SPF, DKIM and DMARC work together to stop spoofing, the record syntax basics, and how to move a policy safely from none to quarantine to reject.
Read guideWriting guides
Word Count for Writers: Targets by Format
Practical word-count and character-count targets for tweets, meta descriptions, blog posts and books, plus the simple math behind reading-time estimates.
Read guideMarkdown Writing Guide: Syntax and Workflow
A practical tour of Markdown syntax — headings, emphasis, lists, links, images, code and tables — plus where it is used and how to preview as you write.
Read guideSocial media guides
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