ToolNook

Free Online Tools

All tools run locally in your browser. No sign-up. No server.

ToolNook is a fast, privacy-friendly toolbox for developers and daily tasks. Format JSON, decode JWT, convert images, generate hashes, and more — all client-side.
TextDeveloperTimeConvertersFiles

Text

5 tools
Text Diff
Compare two texts (line diff).
text
diffcompare
Markdown Preview
Live preview Markdown → HTML.
text
markdownpreview
Text Tools
Trim/dedupe/sort/remove empty lines.
text
textlines
Case Converter
camel/snake/kebab/Title case.
text
case
Word Count
Count characters/words/lines.
text
count

Developer

11 tools
JSON Formatter
Pretty-print, minify, and validate JSON.
dev
jsonformatminifyvalidate
UUID v4 Generator
Generate UUID v4 locally.
dev
uuidv4
Query String Parser
Parse/build URL query strings.
dev
queryurl
JSON ↔ YAML
Convert JSON and YAML.
dev
yamljson
Hash Generator
SHA-256 / SHA-1 locally.
dev
sha256sha1
JWT Decoder
Decode header/payload locally (no verify).
dev
jwtdecode
Regex Tester
Test patterns against text.
dev
regex
MD5 Encrypt
32/16 MD5 (lower/upper) with copy buttons.
dev
md5hash
JSON Format
Format/minify/validate JSON.
dev
jsonformat
CSS Format
Format/minify CSS.
dev
cssformat
CSS Gradient
Edit linear-gradient and copy CSS.
dev
cssgradient

Time

3 tools
Epoch Converter
Convert Unix timestamps ↔ dates.
time
epochunixtimestamp
Cron Parser
Preview next run times.
time
cronschedule
Timestamp Converter
Unix timestamp ↔ date time.
time
timestamptime

Converters

11 tools
Base64 Encode / Decode
Encode or decode Base64 (UTF-8) in-browser.
convert
base64encodedecode
URL Encode / Decode
Encode or decode URL components.
convert
urlencodedecode
Color Converter
HEX ↔ RGB ↔ HSL.
convert
colorhexrgbhsl
Bytes Converter
Bytes ↔ human readable.
convert
byteskibmib
UTF-8 ↔ Unicode
Chinese ↔ UTF-8 percent ↔ Unicode escape.
convert
utf8unicode
Base64 Encrypt (UTF-8)
Text Base64 encode/decode (UTF-8).
convert
base64utf8
Exchange Rate
Currency converter.
convert
fxcurrency
RMB Uppercase
RMB number → Chinese uppercase.
convert
rmb
Stock Calculator
Basic profit/loss calculator.
convert
stock
Color Table
Browse common colors.
convert
color
Resistor Calculator
5-band resistor value.
convert
resistor

Files

7 tools
Image Converter
PNG/JPG/WebP convert + resize + compress.
files
imagepngjpgwebp
Images → PDF
Combine images into a single PDF.
files
pdfimage
Image → Base64
Convert image file to Base64 data URL.
files
base64image
QR Code Generator
Generate QR code PNG.
files
qrcode
Color Detect
Extract dominant colors from image.
files
colorimage
WeChat Contact QR
Generate vCard QR for adding contact.
files
wechatqrcode
Word Cloud
Generate word cloud image.
files
wordcloud