</>DevTools

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Free online tools for developers

Free Online Tools for Developers

DevTools brings 47 free online developer utilities into one place — JSON formatting, Base64 encoding, JWT decoding, regex testing, SQL formatting, hash generation, UUID generation, and more. Every tool runs client-side in the browser, so your data never touches a server. No signup, no cost, no tracking of the inputs you type — the site is funded entirely by ads.

Available in Korean and English, with per-tool usage guides, common error explanations, and real-world use cases. Works identically on desktop, tablet, and mobile browsers with no app to install.

🔥 Top 5 Most Popular

#1{ }JSON Formatter
Format, validate and beautify JSON data
#2B64Base64 Encode/Decode
Encode or decode Base64 strings
#3JWTJWT Decoder
Decode and inspect JWT tokens
#4.*Regex Tester
Test regular expressions with live matching
#5#Hash Generator
Generate MD5, SHA-256, SHA-512 hashes

🔄Text / Data9

B64Base64 Encode/Decode
Encode or decode Base64 strings
&;HTML Entity
Encode/decode HTML entities
CSVJSON ↔ CSV
Convert between JSON and CSV formats
{ }JSON Formatter
Format, validate and beautify JSON data
$.JSON Path Finder
Query JSON data with JSONPath expressions like $.store.book[*].title
Y/JJSON ↔ YAML
Convert between JSON and YAML formats
PDFMarkdown to PDF
Convert Markdown to a downloadable A4 PDF with live preview (GFM supported)
U+Unicode Converter
Convert between Unicode escapes and text
%20URL Encode/Decode
Encode or decode URL components

🔐Crypto / Security7

#Hash Generator
Generate MD5, SHA-256, SHA-512 hashes
JWTJWT Decoder
Decode and inspect JWT tokens
SGNJWT Token Generator
Generate signed JWT tokens with HS256 from a JSON payload and secret
***Password Generator
Generate secure random passwords
STRPassword Strength Meter
Measure password strength with zxcvbn — entropy, crack time estimate, and suggestions, all in-browser
RSARSA Key Generator
Generate RSA public/private key pairs
IDUUID Generator
Generate random UUID v4 strings

💻Regex / Code7

MINCode Minifier
Minify JavaScript, CSS, and HTML to reduce file size
CRNCron Expression
Parse and explain cron expressions
±Diff Compare
Compare two texts and highlight differences
MDMarkdown Preview
Preview Markdown with live rendering
RX?Regex Cheatsheet
Searchable regex reference: metacharacters, quantifiers, groups, flags, and common patterns (email, URL, phone, IP, UUID)
.*Regex Tester
Test regular expressions with live matching
SQLSQL Formatter
Format and beautify SQL queries

🎨CSS Tools5

PALColor Palette Generator
Generate complementary, analogous, triadic, tetradic, and monochromatic palettes from any base color with HEX/RGB/HSL output
RADCSS Border Radius Generator
Generate CSS border-radius with visual preview
FLXCSS Flexbox Generator
Generate CSS flexbox layouts visually
GRDCSS Gradient Generator
Generate CSS linear and radial gradients visually
SHDCSS Box Shadow Generator
Generate CSS box-shadow with visual preview

🌐Network / API5

APIAPI Tester
Test HTTP requests with custom headers, body, and methods (Postman lite)
/24IP CIDR Calculator
Calculate network, broadcast, subnet mask, host range, and address count from CIDR notation (IPv4 and IPv6)
cRLcURL Converter
Convert cURL commands to code (Python, JS, Go)
200HTTP Status Codes
Look up HTTP status codes and their meanings
IPIP Lookup
Look up your IP address and location

⏱️Time / Calc5

MBByte Converter
Convert between bytes, KB, MB, GB, TB
HEXColor Converter
Convert between HEX, RGB, and HSL colors
SECTime Unit Converter
Convert between microseconds, milliseconds, seconds, minutes, hours, days, weeks, months, and years
UTCTimezone Converter
Convert time between different timezones
TSUnix Timestamp
Convert between Unix timestamps and dates

🧰Misc7

ENV.env Parser
Parse and edit .env files
IMGImage to Base64
Convert images to Base64 data URIs
SCHJSON Schema Generator
Generate JSON Schema from JSON data
AaLorem Ipsum Generator
Generate placeholder text
QR-QR Code Decoder
Decode QR code images locally in the browser — drag and drop or upload to extract URL or text
QR+QR Code Generator
Generate QR codes from text or URLs
URLURL Shortener (Local)
Generate a short code or shareable base64 token from a long URL — stored locally in your browser

Frequently Asked Questions

Is DevTools free?

Yes, all 47+ developer tools are free to use without any signup. The site is supported by advertising, so users are never charged.

Is my data sent to a server?

No. All tools run 100% client-side in your browser. JSON formatting, Base64 encoding, JWT decoding — everything happens locally without server transmission. Safe for sensitive data.

What tools are available?

47 developer tools across text/data conversion, encryption/security, network/API, CSS utilities, and more — including JSON Formatter, Base64, JWT Decoder, Regex Tester, SQL Formatter, Hash Generator, UUID Generator, Color Converter, CSS Gradient, QR Generator.

Do I need to sign up?

No signup required. Every tool is available immediately upon visiting. No personal data is collected; cookies are used only for advertising and analytics.

Does it work on mobile?

Yes, every tool is responsive and works identically on desktop, tablet, and mobile browsers. No app install required.

🌐 Other Tools

🧮
모두의 계산기
Korean tax/finance/health calculators (50+)
🎱
로또 번호 추천
Korean lottery number recommender
漢
한자 사전
Hanja (Chinese chars) dictionary
😀
이모지 복사
Emoji & symbols copy + SNS counter