MiniUtil collection
Free Online Developer Tools
Format, encode, decode, inspect, and transform data with practical utilities for web development.
25 tools · Free · No registration
Browse Developer Tools
JSON Formatter
Format and validate JSON data.
Base64 Encoder/Decoder
Convert text to and from Base64.
Hex Converter
Convert numbers to/from hexadecimal.
URL Encoder/Decoder
Encode and decode URLs.
Favicon Path Checker
Check common favicon and app-icon paths on a website.
Google Preview
Preview how your page appears in Google.
Search Console Opportunity Analyzer
Prioritize positions 4–20, CTR gaps, and localization candidates from private CSV exports.
IP Address
Get your IP address and details.
Hash Generator
Generate SHA-1, SHA-256, SHA-384, and SHA-512 hashes from text.
HTML Encoder/Decoder
Encode text as HTML entities or decode entities back to text.
JWT Decoder
Inspect JWT headers, payloads, and signatures locally in your browser.
UUID v4 Generator
Generate secure random version 4 UUIDs in bulk.
JSON Pointer & Patch Tester
Resolve RFC 6901 pointers and test RFC 6902 JSON Patch operations locally.
Cache-Control Header Builder
Build, parse, and explain HTTP Cache-Control directives with ready-to-use snippets.
SRI Hash Generator & Verifier
Create and verify SHA-256, SHA-384, and SHA-512 Subresource Integrity hashes.
OAuth PKCE Generator & Verifier
Generate and verify RFC 7636 code verifiers, S256 challenges, and authorization URLs.
HAR Viewer & Sanitizer
Inspect HAR network archives and redact credentials, cookies, query values, and bodies.
security.txt Generator
Create and validate RFC 9116 vulnerability disclosure contact files.
CSP Header Builder
Build, parse, and review Content Security Policy headers and server snippets.
Permissions-Policy Builder
Control browser features with HTTP headers and iframe allow attributes.
CORS Header Generator
Build CORS response headers and server snippets with origin and credential checks.
Content-Disposition Generator
Create and parse safe download headers with UTF-8 filename support.
Cookie Header Parser
Parse Cookie and Set-Cookie fields and review common scope and security issues.
JWK Thumbprint Calculator
Calculate RFC 7638 JWK thumbprints and generate temporary public key examples.
Data URI Generator
Convert text or small files to Base64 or percent-encoded data URLs and snippets.