Free tools · no account
Free online tools that run in your browser
QR codes, passwords, JSON, converters and calculators — no signup, no uploads, no waiting. Everything runs on your device.
All tools
Generators
QR Code Generator
Turn a link or any text into a downloadable PNG QR code. Static, never expires.
Open tool →Wi-Fi QR Code Generator
Let guests join your Wi-Fi by scanning a code. WPA/WPA2/WPA3, WEP and open networks.
Open tool →Password Generator
Strong random passwords with custom length and character sets, plus entropy in bits.
Open tool →UUID Generator
Generate 1 to 50 random UUID v4 values and copy them all at once.
Open tool →Text tools
Word Counter
Live word, character, sentence and paragraph counts with reading time.
Open tool →Case Converter
Switch text between UPPER, lower, Title, Sentence, camelCase, snake_case and kebab-case.
Open tool →Regex Tester
Test a JavaScript regular expression against your text, inspect groups and preview replacements.
Open tool →Markdown Preview
Write Markdown and see a rendered preview instantly, including GFM tables and task lists.
Open tool →Developer tools
Converters & encoders
Base64 Encoder
Encode text to Base64 or decode it back, with UTF-8 and URL-safe support.
Open tool →URL Encoder
Percent-encode a value or a full URL, and decode %xx sequences back to text.
Open tool →Byte Size Converter
Convert between bytes, kB/MB/GB (decimal) and KiB/MiB/GiB (binary).
Open tool →Unit Converter
Length, weight, volume, area, speed, storage and temperature in one place.
Open tool →Color Converter
HEX, RGB and HSL conversion plus contrast against white and black.
Open tool →PX to REM Converter
Convert px, rem and em with a configurable root and parent font size, plus a common size table.
Open tool →Time & date
Unix Timestamp Converter
Epoch seconds or milliseconds to ISO, UTC, local time and back.
Open tool →Cron Expression Explainer
Turn a five-field cron expression into plain English and the next five run times.
Open tool →Calculators
BMI Calculator
Body mass index from metric or imperial measurements, with category and healthy range.
Open tool →Percentage Calculator
Three everyday percentage questions answered at once.
Open tool →Age Calculator
Exact age in years, months and days, plus total days and next birthday.
Open tool →Reference lookup
HTTP Status Code Lookup
Search HTTP status codes by number, reason phrase or symptom, and open the full reference entry.
Open tool →MIME Type Lookup
Find the Content-Type for a file extension and see what each media type is used for.
Open tool →Port Lookup
Search TCP and UDP ports by number, service or risk, and open the reference entry.
Open tool →Web & network
Security
Reference
Short, sourced entries for the terms our tools act on — written for humans and machines alike.
Web & HTTP
HTTP Status Codes — Meanings, Causes and Fixes
What each HTTP status code means, when a server should return it, what causes it in practice and how to fix it. Facts from RFC 9110, paired with free debugging tools.
30 entries →HTTP Header Reference
What the common HTTP request and response headers mean, how they are parsed, and which ones carry security consequences. Facts from RFC 9110, RFC 9111 and RFC 6265, paired with a header inspector.
15 entries →MIME Types and Content Types — Reference
What each common media type is for, which file extensions map to it, how browsers and servers treat it, and the mistakes that break uploads and APIs.
23 entries →Networking
Encoding & data
QR Code Reference
How QR codes actually work: error correction, versions, capacity, quiet zones, mask patterns, Micro QR and the Wi-Fi QR payload format — each entry paired with a generator.
13 entries →UUID Reference
UUID versions explained with the bits that matter: v4 randomness, v7 time ordering, v1/v3/v5 construction, the nil UUID, GUID differences and collision math — each with a generator.
11 entries →Design & frontend
Color Format Reference
Hex, RGB, HSL, HSV, CMYK, alpha and WCAG contrast explained with exact ranges and formulas — each entry paired with a converter that runs in your browser.
10 entries →CSS Unit Reference
How CSS length units actually resolve: px, rem, em, ch, ex, viewport units, percentages, grid fr and calc/clamp. Facts from the CSS Values specification, paired with a px/rem converter.
10 entries →Time & scheduling
Text & patterns
Regular Expression Reference
How regular expression syntax works in JavaScript and common engines: character classes, quantifiers, anchors, groups, lookaround, backreferences, flags and backtracking. Facts from the ECMAScript and PCRE specifications, paired with a regex tester.
10 entries →Markdown Reference
Markdown syntax with the edge cases that actually bite: headings, paragraphs, emphasis, links, images, lists, code, blockquotes, tables and task lists. Facts from CommonMark and GitHub Flavored Markdown, paired with a live previewer.
10 entries →Security
Why browser-based tools
Most online utilities send what you paste to a server. These tools do the work in JavaScript on your own device, so a password, a JSON payload or a Wi-Fi key never travels over the network. That also makes them fast: there is no round trip and no queue.
The only thing this site measures is that a page was viewed. The pageview counter records the path, referrer and UTM tags, plus a daily rotating hash instead of your IP address. It never receives tool input.
What is included
- Codes and secrets: QR codes, Wi-Fi QR codes, passwords, UUIDs.
- Text and data: word counter, JSON formatter, Base64, case converter.
- Converters: units, colors, Unix timestamps.
- Calculators: BMI, percentages, exact age.
Each tool page explains how the calculation works, so you can check the result instead of trusting a black box.
Accuracy and limits
Converters use standard exact factors where they exist (an inch is exactly 25.4 mm; a pound is exactly 0.45359237 kg). Calculators show the formula so you can verify the output. Health and legal figures are screening aids, not advice: BMI does not diagnose anything, and age rules should always be checked against the authority that asks for them.
Frequently asked questions
Are the tools really free?
Yes. Every tool on this site is free to use, with no account, trial or export fee. The site is supported by a small newsletter, not by paywalling features.
Do I need to create an account?
No. Tools open and work immediately. The email form is optional and only used to announce new tools.
Is my input uploaded to a server?
No. Tool calculations run in your browser. The pageview beacon sends only the page path, referrer and UTM tags with a daily hashed visitor key — never the text, password, JSON or files you enter.
Can I use the output commercially?
Yes. QR codes, generated passwords, converted values and other output are yours to use. There is no attribution requirement. Make sure you have the rights to whatever content you encode.
Do the tools work offline?
After a page and its scripts are cached by your browser, most tools keep working without a network connection. The QR tool loads its encoder library on first use, so that first run needs the file to be reachable.
How often are new tools added?
New utilities are added in small batches. Join the optional email list if you want one short notice when a batch ships.