DevToolkit Pro

Data Stays Local

Works Offline

Input Never Tracked

Open Logic

Works Offline.
Your Data Stays Here.

All computation runs in your browser. 132 tools, your input never uploaded, 100% local.

Browse Workflows

Works in airplane mode · Add to home screen for offline · Free forever

Chain tools into pipelines

Stop copy-pasting between tools. Chain multiple tools into automated pipelines and run them with one click. Every step runs locally.

JWT Token Inspector

Decode JWT header, decode payload, check expiry and signature algorithm

4 steps~2 seconds

JWT Token Input→Header Decoder→Payload Decoder→Expiry Checker

JSON Beautify & Type Generation

Format JSON, extract all key paths, generate TypeScript type definitions

4 steps~3 seconds

JSON Input→JSON Formatter→Key Path Extractor→TypeScript Type Generator

Data Fingerprint Generator

Generate SHA256 hash, Base64 encode, and extract a short fingerprint

4 steps~3 seconds

Data Input→SHA256 Hash→Base64 Encode Hash→Short Fingerprint

Browse 13 Workflows

Popular Tools

JSON Formatter - Online JSON Format & Beautify

Online JSON formatter: beautify, minify, validate JSON with one click. Convert to TypeScript/Go/Java. Unicode-safe, supports Chinese and Emoji.

Base64 Encoder/Decoder - Online Base64 Encode/Decode

Online Base64 encoder and decoder with full Unicode support (Chinese, Emoji, multi-byte characters). All processing runs locally in your browser. No data sent to servers.

API Tester - Online HTTP Request Testing Tool

Online API tester: GET/POST/PUT/DELETE/PATCH with custom Headers/Body, 30s timeout with cancel. Postman alternative.

JWT Decoder - Online JWT Token Decode & Signature Verify

Online JWT (JSON Web Token) decoder with HS256 signature verification. View Header, Payload, and Signature segments. Decoded locally in your browser, token never sent to server.

Regex Tester - Online Regular Expression Tester

Online regex tester with support for g/i/m/s flags. Real-time match highlighting. Runs locally in your browser for fast regex debugging.

UUID Generator - Online UUID v4 / NanoID / ULID

Online unique ID generator: UUID v4 (RFC 4122), NanoID (URL-safe), ULID (sortable). Powered by crypto.getRandomValues. Generated locally in your browser.

Code Formatter - Online Prettier Code Formatter

Online code formatter powered by Prettier. Supports JavaScript, HTML, CSS, SQL formatting and safe minification. Protects string literals from being broken.

Password Generator - Online Secure Password Generator

Online secure password generator: customizable length, uppercase, lowercase, numbers, symbols. Uses crypto.getRandomValues for true randomness. Generated locally, never stored.

All Tools

Data

JSON suite, data format conversion, schema validation

JSON ToolsFormat ConversionMarkdown Tools

Text

String operations, text analysis, encoding conversion

Text OperationsEncoding

Code

Code formatting, code generation, config generation

Format & MinifyCode GenerationConfig & StyleCheatsheets

Security

Hash, encryption, authentication, passwords

Hash & HMACEncryptionAuth & CertificatesPasswords

Network

API testing, HTTP, URL parsing, IP calculation

API & HTTPURL & UA ParsingIP & SubnetRegex

Media

Image tools, QR codes, color tools, date & time

ImagesQR CodesColorsTime & DateID Generation

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Summary: DevToolkit Pro is a privacy-first, fully client-side developer toolkit: JSON formatter/converter, API tester, Base64/URL/JWT, regex tester, Hash/HMAC/AES, UUID/NanoID/ULID, Cron parser, CIDR calculator, code formatter, text diff and 130+ tools. All data stays in your browser.