Blog

Guides, tutorials, and tips on online tools, privacy, and productivity.

Explore our 12 articles. They include step-by-step guides for using our tools and posts on online privacy, cryptography, web performance, and development best practices.

file security10 min·Jul 17, 2026

How to Check a File Before You Open It

Use provenance, real file type, hashes, macros, and malware scanning as layers of evidence—without mistaking a clean result for proof of safety.

metadata11 min·Jul 17, 2026

File Metadata: EXIF, PDF, and Office

Inspect location, author, software, and document-history metadata before sharing a file, and understand what removal tools may leave behind.

hash7 min·Feb 21, 2026

Hash Functions: SHA-2, SHA-3, and HMAC

Understand checksums, cryptographic hashes, HMAC, collision resistance, and why SHA-1 or MD5 should not protect security-sensitive data.

speed test11 min·Feb 21, 2026

Speed Tests: Download, Upload, Ping, Jitter

Learn how browser speed tests measure transfers, why results vary, and how to run repeatable comparisons without treating one result as an ISP guarantee.

IP8 min·Feb 13, 2026

Public vs Private IP Addresses Explained

Understand what your public IP reveals, how private address ranges work, and why IP geolocation is approximate rather than an identity check.

PDF2 min·Feb 13, 2026

How to Merge PDFs Locally in Your Browser

A practical walkthrough of local PDF merging, ordering, limits, privacy properties, and the cases that still require a full PDF editor.

passwords2 min·Feb 13, 2026

Strong Passwords: Length and Randomness

Learn what a password generator can and cannot guarantee, why length and randomness matter, and how to store unique passwords safely.

QR3 min·Feb 13, 2026

QR Codes: Content, Errors, and Scanning

Understand static QR payloads, error correction, quiet zones, sizing, privacy, and how to verify a code before printing it.

currency3 min·Feb 13, 2026

Currency Rates, Spreads, and Limits

Use reference rates correctly, understand provider spreads, and learn exactly where ToolsFree obtains its daily currency data.

units10 min·Feb 13, 2026

Unit Conversion: SI and Precision

A worked guide to unit factors, temperature offsets, significant digits, and the difference between decimal and binary data units.

images3 min·Feb 13, 2026

Image Compression: Formats and Tradeoffs

Compare PNG, JPEG, WebP, and AVIF tradeoffs, understand browser-side re-encoding, and choose settings using repeatable visual checks.

JSON10 min·Feb 13, 2026

JSON Format: Syntax, Errors, and Safe Use

Learn JSON's actual grammar, diagnose common parser failures, and format or inspect data locally without confusing syntax validation with schema validation.