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Single-purpose utilities that run in your browser. No sign-up required.
Popular articles
View allMost Frequent English Words List: 50 Words, COCA Frequency Data
The 50 most frequent English words ranked by COCA frequency (per million words). Covers Zipf's law, function vs content words, and NLP stop-word tips.
Percent-Encoding Cheatsheet: encodeURI vs encodeURIComponent and Double-Encoding Bugs
encodeURI and encodeURIComponent escape different characters, and choosing the wrong one breaks query strings. RFC 3986 rules with real examples.
Go/No-Go Test Explained: What It Measures and Why to Train It
The Go/No-Go task measures response inhibition — the ability to stop an automatic action. How it works, what commission and omission errors mean, age norms, and ADHD research.
Tools
Unicode Font Generator
Turn any text into 22 fancy fonts — bold, italic, script, fraktur, double-struck, circled — and paste anywhere on Instagram, Twitter, TikTok, Discord, LinkedIn.
Reaction Tests
Measure your reaction speed with simple, choice, audio, and go/no-go tests. Track progress over time with charts and statistics.
Copy Page Text
The fastest way to copy all text from a webpage for notes, documents, or sharing with a single click.
Smart Text Cleaner
Remove extra spaces, fix line breaks, and clean formatting from any text instantly.
Word Case Swap
Convert text between UPPER, lower, Title Case and more with one click.
Character Counter
Count characters, words, sentences, paragraphs, and estimate reading time instantly.
JSON Formatter
Format, validate, and minify JSON with syntax highlighting and error detection.
Base64 Encoder
Encode and decode Base64 strings instantly. Supports Unicode text.
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes from text — with hex or Base64 output. Runs entirely in your browser.
Word Frequency Analyzer
Extract unique words, count frequency, and filter out known words. Perfect for language learners to find new vocabulary in texts.
URL Encoder & Decoder
Encode and decode URLs instantly using encodeURIComponent. Supports both encode and decode modes with live output.
UUID Generator
Generate UUID v4 identifiers using the Web Crypto API. Copy instantly, keep a history of recent UUIDs.
Color Converter
Convert colors between HEX, RGB, and HSL formats. Pick with color picker or enter values manually.
Timestamp Converter
Convert Unix timestamps to human-readable dates and back. Supports UTC, local time, ISO 8601, and relative time.
Text Diff Viewer
Compare two texts and highlight added and removed lines. LCS-based diff running entirely in your browser.
Noise Meter
Measure real-time sound levels in dB using your device microphone. Instantly see noise categories from quiet to very loud.
BPM Tapper
Tap along to any beat and estimate tempo, average BPM, tap consistency, and timing spread.
Chord Progression Generator
Generate song-ready chord progressions by key, mode, genre, and mood with Roman numerals.
Song Key Finder
Find likely keys from a chord progression, compare candidates, and see matching scales.
From the Blog
View allHow to Find BPM by Tapping the Beat
Tap tempo explained for musicians and producers: how BPM works, why averages matter, how to tap accurately, and common tempo ranges by style.
Common Chord Progressions Every Songwriter Should Know
A practical guide to common chord progressions for songwriting, including I-V-vi-IV, ii-V-I, twelve-bar blues, minor-key loops, and how to vary them.
How to Find the Key of a Song from Chords
Find out what key a song is in from its chords: a step-by-step method using diatonic chord sets, cadences, melody notes, and relative major vs minor clues.
MD5 vs SHA-256: Which Hash Should You Use (and Why MD5 Isn't Dead)
MD5 is broken for security but fine for checksums; SHA-256 is the modern default. Collision history, an avalanche demo, a speed/use-case table, and how to pick.
Why You Must Salt Password Hashes (Salt, Pepper, and Why MD5 Won't Save You)
Plain hashes fall to rainbow tables. Learn how per-user salts and an app-wide pepper work, and why passwords need slow KDFs — bcrypt, scrypt, Argon2id — not MD5 or SHA-256.
How to Verify a File Checksum with SHA-256 (Step by Step, Every OS)
Verify downloads with SHA-256 on Windows, macOS, and Linux. Exact commands, how to compare checksums, checksums vs GPG signatures, and the pitfalls that change a hash.
Unicode Fancy Fonts on Instagram: How They Work and When Not to Use Them
Bold, italic, and script "fonts" in Instagram bios are not fonts at all — they are Unicode characters. Here is how they work, where they break, and why screen readers cannot read them.
10 Invisible Characters That Silently Break Copy-Paste
Zero-width spaces, BOM, and NBSP silently break string equality, JSON parsers, and trim(). 10 hidden Unicode characters with code examples and a one-click fix.
Why camelCase vs snake_case Matters in Code
Naming conventions affect readability, tooling, and team velocity. A practical guide to choosing the right case style for your project.
Average Reaction Time by Age: What's Normal?
Reaction time varies by age, sleep, and practice. See the benchmarks, learn what affects your speed, and test yourself.
Top 5 JSON Errors and How to Find Them Fast
Trailing commas, missing quotes, wrong encoding — the most common JSON mistakes that break APIs and configs. Learn how to spot and fix them instantly.
How to Measure Reaction Time Accurately
Three methods to measure reaction time — ruler drop, online tests, and lab experiments. Pros, cons, and tips for getting accurate results.
Why Counting Characters Matters: Twitter, SEO & SMS Limits
Character limits are everywhere — social media posts, meta titles, SMS messages, database fields. Learn the exact limits and how to stay within them.
Reaction Time vs Reflex: What Is the Difference?
Reaction time and reflexes are not the same thing. Learn the neuroscience behind each, see real-world examples, and find out which one you can actually train.
Why Your Character Count Differs Between Apps (and Which One Is Right)
Twitter, SMS, and Python all count characters differently. The same text shows as 10 in one app and 12 in another. Here is exactly why.
7 Whitespace Bugs That Break Production Deploys
Trailing spaces in YAML, Windows CRLF line endings in bash scripts, BOM markers — real whitespace mistakes that trigger production failures and take hours to debug.
CSS Color Conversions: HEX, RGB, HSL — Cheatsheet and When to Use Each
Everything you need to convert CSS colors between HEX, RGB, and HSL formats. Includes hand-calculation formulas, JavaScript code, and when each format is the right choice.
UUID v4 vs v7: When to Use Each (and Why It Affects Database Performance)
UUID v4 is random and fragments database indexes. UUID v7 is time-ordered and sorts naturally. When to use each, with collision math and migration advice.
How to Extract Webpage Text to Markdown (Without Ads or Clutter)
Plain copy-paste loses headings, lists, and links. Here is how to convert any webpage to clean Markdown with one click — ready for ChatGPT, Claude, Obsidian, or Notion.
Base64 33% Size Overhead Explained: RFC 4648 Formula & When It Matters
Base64 maps 3 bytes → 4 chars (4/3 ratio per RFC 4648), adding 33% to every payload. See the size formula, padding rules, and when to skip Base64 entirely.
Unix Timestamp Pitfalls: Y2038, Milliseconds vs Seconds, and Timezone Hell
Unix timestamps look simple — seconds since 1970 UTC — until Y2038 overflow, milliseconds-vs-seconds mismatch, and timezone bugs corrupt your data.
How Diff Algorithms Work: Myers, Patience, Histogram — Why git diff Sometimes Looks Wrong
Diff is not one algorithm but a family. Myers, patience, and histogram each give different output for the same files. How and when each one wins.
Choice Reaction Time and Hick's Law: Why More Options = Slower Decisions
Choice reaction time grows logarithmically with the number of options — Hick's Law. The cognitive cost of choice, with norms, esports data, and the Stroop wrinkle.
Audio vs Visual Reaction Time: Why Sound Is 30-50 ms Faster Than Light
Audio reaction time beats visual by ~30-50 ms because sound reaches the cortex through fewer synapses. The neuroscience, sports examples, and measurement caveats.
How to Measure Noise Level in an Office: A Practical Guide
A practical, standards-based guide to measuring office noise: OSHA and WHO limits, microphone placement, A-weighting vs C-weighting, and the real limits of browser-based meters.
Frequently Asked Questions
Which tool counts characters for Twitter, SMS, or SEO meta tags?
Use the Character Counter at /utilities/character-counter. It tracks characters, words, sentences, paragraphs, and reading time live, with separate counts that match Twitter, SMS GSM-7 segments, and Google meta-title limits.
Where can I encode and decode Base64 strings without uploading them?
The Base64 Encoder at /utilities/base64-encoder runs entirely in your browser. It supports Unicode text in both directions, so you can encode, decode, and round-trip strings without sending data to a server.
How do I format and validate JSON quickly?
Open the JSON Formatter at /utilities/json-formatter. It pretty-prints, minifies, and highlights syntax errors — trailing commas, unquoted keys, mismatched brackets — inline, so you can fix invalid JSON without leaving the page.
How can I generate a UUID v4 identifier on demand?
The UUID Generator at /utilities/uuid-generator produces UUID v4 values using the Web Crypto API. You can copy any ID in one click and keep a session history of the last few values you generated.
How do I convert CSS colors between HEX, RGB, and HSL?
Use the Color Converter at /utilities/color-converter. Pick a color or paste any HEX, RGB, or HSL value and see the other two formats update in real time, with copy buttons for each notation.
What is a reaction time test and how do I take one?
Reaction tests measure how fast you respond to a stimulus. The hub at /reaction-tests offers four variants — simple, choice, audio, and Go/No-Go — that each isolate a different cognitive ability, from raw reflexes to decision-making and impulse control.
Is my data private when I use these tools?
Yes. All tools process input locally in your browser — text, files, and microphone audio never leave your device. There is no account, no upload, and no server-side logging of the content you paste or record.
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