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

4 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

Developer

8 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

Time

2 tools
Epoch Converter
Convert Unix timestamps ↔ dates.
time
epochunixtimestamp
Cron Parser
Preview next run times.
time
cronschedule

Converters

5 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

Files

3 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