Web tools that explain themselves
JSON, Base64, JWT, color, time and more — every tool comes with a plain-English guide on how it works and when to reach for it. No signup, no clutter.
Latest articles
Color & Design Rounded Corners in CSS: border-radius, Nested Radii, and Squircles The border-radius rules most developers half-know — shorthand order, the % gotcha, the pill trick, the inner = outer − gap formula for nested corners, and squircles with the new corner-shape property. Web 401 vs 403: Unauthorized vs Forbidden, Explained The real difference between HTTP 401 and 403 — authentication vs authorization — with a one-line rule to pick the right one, an API cheat sheet, and when to return 404 instead. JSON & Data How to Fix Common JSON Errors The handful of mistakes behind almost every "invalid JSON" message — trailing commas, quotes, brackets — and exactly how to spot and fix each one. Color & Design HSL vs RGB vs HEX: Which Color Format Should You Use? Three ways to write the same color, and why the right one depends on whether you're picking a color or adjusting one. Encoding & Tokens UTF-8 vs UTF-16 vs UTF-32, Explained Simply Three ways to store the same Unicode text as bytes. How they differ, why UTF-8 won the web, and when the others still matter. Encoding & Tokens URL Encoding vs HTML Encoding vs Base64: When to Use Each Three encodings that look similar and solve different problems. What each does, and how to pick the right one so text survives where it's going. Encoding & Tokens JWT Security: 7 Mistakes That Get Tokens Stolen The common JWT mistakes that lead to account takeover — from the alg:none trap to storing tokens where XSS can grab them — and how to avoid each. SEO 301 vs 302 Redirects: The SEO Guide The difference between permanent and temporary redirects, what each does to your search rankings, and when to use 301, 302, 307 or 308. SEO Social Media Character Limits: The 2026 Cheat Sheet Every character limit that matters on X, Threads, Instagram, TikTok, LinkedIn, Facebook, YouTube and more — plus the hidden truncation points that matter even more.
The toolbox
Companion utilities for the guides — each with a built-in explainer, no signup.
Text
Text Word Counter Count words, characters, sentences, paragraphs and reading time in real time — free and private. Text Case Converter Convert text to UPPERCASE, lowercase, Title Case, Sentence case, camelCase, snake_case and kebab-case instantly. Text Lorem Ipsum Generator Generate Lorem Ipsum placeholder text — by paragraph, sentence or word — right in your browser, with a guide to what it is and why designers use it. Text Text Diff Checker Compare two blocks of text and see exactly what changed — added and removed lines highlighted — right in your browser, with nothing uploaded.
JSON & Data
JSON & Data JSON Formatter & Validator Format, validate and minify JSON online — with a plain-English guide to what JSON is, how it's structured, and the rules that keep it valid. JSON & Data JSON to CSV Converter Convert a JSON array of objects to CSV in your browser — plus a clear comparison of JSON vs CSV vs YAML vs XML and when to use each.
Encoding & Tokens
Encoding & Tokens Base64 Encoder & Decoder Encode and decode Base64 online (UTF-8 safe, with URL-safe option) — plus a clear explanation of what Base64 is, how it works, and when to use it. Encoding & Tokens JWT Decoder Decode a JSON Web Token in your browser to inspect its header and payload — with a plain-English guide to how JWTs are structured, signed, and validated. Encoding & Tokens URL Encoder & Decoder Encode and decode URLs and query strings in your browser — with a clear guide to percent-encoding, reserved characters, and when to encode a component vs a whole URL. Encoding & Tokens Unicode Character Inspector Break any text down character by character — code point, HTML entity and UTF-8 bytes — in your browser. Works with symbols, accents and emoji.
Color & Design
Color & Design Color Contrast Checker Check color contrast against WCAG AA and AAA in your browser — plus a plain-English guide to contrast ratios, the thresholds, and how to fix failing colors. Color & Design Color Converter (HEX, RGB, HSL) Convert colors between HEX, RGB and HSL in your browser, with a live preview — plus a clear guide to what each notation means and when to reach for it.
Date & Time
Web Reference
Image
Image Round Image Corners Add rounded corners to any image with a live preview — per-corner radius, iOS-style squircles, optional border and background, transparent PNG/WebP or JPEG output. Nothing is uploaded. Image App Icon & Asset Resizer Resize one 1024×1024 icon into every iOS, Android and web size — and scale @3x/@4x image sets down to every density — right in your browser. Nothing is uploaded.
