Private browser-based utilities
Fast online tools for developers, designers, and digital work.
Hash strings, format JSON, inspect IP addresses, encode data, generate passwords, and convert assets with clean tools that are built for speed, privacy, and search.
Tools
Utilities for the task in front of you.
Use browser-first converters, generators, formatters, security helpers, and AI-agent preparation tools without uploading sensitive inputs.
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Popular tools
Hash & checksums
MD5 Generator
Generate an MD5 hash from text directly in your browser. Useful for checksums, legacy systems, and quick comparisons.
Hash & checksums
SHA-1 Generator
Generate SHA-1 hashes locally in your browser for legacy checksums and compatibility checks.
Hash & checksums
SHA-256 Generator
Create SHA-256 hashes locally in the browser using the Web Crypto API.
Hash & checksums
SHA-512 Generator
Create SHA-512 hashes locally in the browser using the Web Crypto API.
Hash & checksums
File Checksum Generator
Generate MD5 and SHA-256 checksums for local files without uploading them.
Hash & checksums
Hash Compare
Compare two hashes locally with whitespace cleanup and case-insensitive matching.
Encoding
Base64 Encode and Decode
Encode text to Base64 or decode Base64 back to readable text in the browser.
Encoding
Base64 Image Converter
Convert PNG, JPEG, WebP, GIF, and AVIF images to Base64 data URLs and back locally in your browser.
Encoding
Base64 File Converter
Convert local files to Base64 data URLs and decode Base64 back into downloadable files in your browser.
Data formatters
JSON Formatter and Validator
Format, validate, and minify JSON locally with clear error messages.
AI & agents
llms.txt Generator
Generate a practical llms.txt draft for AI assistants, agents, and documentation discovery.
AI & agents
Secrets in Prompt Scanner
Scan prompts, logs, configs, and agent context locally for tokens, API keys, JWTs, private URLs, and risky credentials before sharing them with AI tools.
AI & agents
Prompt and Agent Instruction Linter
Review AI prompts and agent instructions locally for vague goals, conflicting requirements, risky permissions, missing success criteria, and weak safety boundaries.
AI & agents
Context Window Planner
Estimate prompt token usage, reserve output space, and split long documents into agent-ready context chunks locally in your browser.
AI & agents
MCP Tool Manifest Inspector
Inspect MCP-style tool manifests locally for naming issues, weak descriptions, invalid input schemas, risky capabilities, and agent safety gaps.
AI & agents
OpenAPI to AI Tool Schema Converter
Convert OpenAPI JSON or YAML operations into AI-agent-friendly tool schemas with parameters, descriptions, and risk warnings.
Data formatters
JSON Minifier
Minify JSON locally in your browser and validate that the input is valid JSON.
Data formatters
JSON Path Explorer
Explore JSON paths, inspect nested values, and copy selected results locally in your browser.
Data formatters
JSON Schema Validator
Validate JSON against a practical JSON Schema subset locally in your browser.
Data formatters
Cron Expression Helper
Explain 5-field cron expressions and calculate upcoming run times locally.
Data formatters
CSS Minifier
Minify CSS locally in your browser with conservative whitespace and comment cleanup.
Data formatters
HTML Formatter and Minifier
Format or minify HTML snippets locally as text without rendering untrusted markup.
Data formatters
JavaScript Minifier
Minify JavaScript snippets locally with conservative whitespace and comment cleanup.
Data formatters
XML Formatter and Minifier
Format, validate, and minify XML locally in your browser.
Data formatters
XML to JSON Converter
Convert XML documents into readable JSON locally in your browser.
Data formatters
YAML to JSON Converter
Convert YAML documents to formatted JSON locally in the browser.
Data formatters
JSON to YAML Converter
Convert JSON objects and arrays into clean YAML locally in your browser.
Data formatters
CSV to JSON Converter
Convert CSV rows into JSON arrays locally, with quoted fields and custom delimiter support.
Data formatters
JSON to CSV Converter
Convert JSON arrays or objects into CSV locally in your browser.
Data formatters
Unix Timestamp Converter
Convert Unix timestamps to readable dates and parse date strings back to timestamps locally.
Data formatters
Regex Tester
Test JavaScript regular expressions against sample text locally in the browser.
Network & web
What Is My IP Address?
See the public IP address your browser is using to reach Lumio Utils.
Network & web
User-Agent Parser
Parse browser, operating system, device type, and rendering engine from a User-Agent string locally.
Network & web
DNS Lookup
Look up public DNS records with protections against local and private network targets.
Network & web
HTTP Headers Checker
Inspect response headers for public HTTP and HTTPS URLs without following redirects.
Network & web
HTTP Status Code Reference
Search HTTP status codes by number, phrase, class, and common usage locally in your browser.
Network & web
CORS Checker
Test a public URL with a browser-style CORS preflight request and inspect Access-Control headers.
Network & web
SSL Certificate Checker
Inspect the TLS certificate, issuer, expiry date, SANs, protocol, and cipher for a public HTTPS host.
Network & web
URL Parser
Parse URLs into protocol, host, path, query parameters, hash, and origin locally in your browser.
Network & web
URL Query Builder and Parser
Build, parse, edit, encode, and copy URL query parameters locally in your browser.
Text utilities
UUID Generator
Generate random UUID v4 values in your browser.
Text utilities
Word and Character Counter
Count words, characters, sentences, paragraphs, and estimated reading time locally in the browser.
Text utilities
Text Cleanup and Whitespace Normalizer
Clean pasted text locally by trimming lines, normalizing spaces, tabs, blank lines, and line endings.
Text utilities
Remove Duplicate Lines
Remove duplicate lines from text locally with case-sensitive, trim, preserve-order, and sort options.
Text utilities
Sort Lines
Sort lines locally with ascending, descending, natural, case-insensitive, trim, and empty-line options.
Text utilities
String Diff
Compare two blocks of text line by line locally in the browser.
Text utilities
Markdown Preview
Preview common Markdown syntax locally and copy safe HTML output.
Text utilities
String Case Converter
Convert text between title case, sentence case, uppercase, lowercase, camelCase, PascalCase, snake_case, and kebab-case.
Text utilities
Slug Generator
Turn titles and phrases into clean URL slugs with configurable separators.
Security helpers
Password Generator
Generate strong passwords locally without sending them to a server.
Security helpers
JWT Decoder
Decode JSON Web Token headers and payloads locally in your browser without uploading tokens.
Encoding
URL Encode and Decode
Encode and decode URL components safely for query strings and APIs.
Encoding
HTML Entity Encode and Decode
Encode text for safe HTML display or decode HTML entities back to readable text in the browser.
Encoding
QR Code Generator
Create QR codes locally for URLs, Wi-Fi notes, contact text, and short messages.
Image & SVG
SVG to Android Vector Drawable
Convert supported SVG paths into Android Vector Drawable XML.
Image & SVG
SVG Viewer
Preview SVG files locally and inspect their dimensions, viewBox, and element counts.
Image & SVG
SVG to PNG Converter
Convert SVG artwork into PNG images locally in the browser with selectable scale.
Image & SVG
SVG Optimizer
Optimize and sanitize SVG markup locally with safe preview, file loading, and download.
Image & SVG
PNG to WebP Converter
Convert PNG images into compact WebP files locally in your browser.
Image & SVG
WebP to PNG Converter
Convert WebP images back into PNG files locally without uploading them.
Image & SVG
Image Resize
Resize PNG, JPEG, and WebP images locally in your browser with format and quality controls.
Image & SVG
Image Compress
Compress JPEG, PNG, and WebP images locally in your browser with format and quality controls.
Image & SVG
Favicon Generator
Generate common favicon PNG sizes locally from a source image.
Image & SVG
Color Converter
Convert colors between HEX, RGB, HSL, HSV, and CSS-ready formats locally.
Image & SVG
Contrast Checker
Check WCAG text contrast ratios between foreground and background colors locally.
Image & SVG
EXIF Viewer
Inspect camera and photo metadata locally before sharing an image.
Image & SVG
EXIF Remover
Remove private metadata from photos before sharing them online.
SEO & marketing
Meta Tag Preview
Preview title and description snippets for search and social sharing.
SEO & marketing
Title and Description Checker
Check SEO title and meta description lengths, preview a search snippet, and tune copy locally.
SEO & marketing
Open Graph Preview
Preview Open Graph and social sharing metadata locally before publishing a page.
SEO & marketing
UTM Builder
Build campaign URLs with UTM source, medium, campaign, term, and content parameters locally.
SEO & marketing
Robots.txt Generator
Generate a simple robots.txt file with sitemap, allow, disallow, and crawl-delay directives.
SEO & marketing
Sitemap.xml Generator
Generate a clean XML sitemap from a list of URLs with lastmod, priority, and changefreq options.
Interactive learning
Courses
JavaScript Course
Learn JavaScript with runnable browser examples, small exercises, and practical links to developer tools.
44 lessons readyBeginnerNode.js Course
Learn Node.js with real terminal commands, project files, pure Node.js APIs, and backend examples you can run locally.
6 lessons readyStructured for roaming
Categories
Hash & checksums
Generate and compare hashes for text and files without uploading sensitive data.
Encoding
Encode, decode, escape, and clean strings for URLs, HTML, APIs, and data formats.
Data formatters
Format, validate, minify, and convert structured data such as JSON, YAML, XML, and CSV.
Network & web
Inspect IP addresses, headers, DNS, certificates, and browser request details.
Image & SVG
Convert, inspect, optimize, and prepare image assets for web and mobile apps.
SEO & marketing
Preview metadata, build campaign URLs, create robots files, and validate search snippets.
AI & agents
Prepare websites, docs, APIs, prompts, and tool schemas for AI assistants and agent workflows.
Text utilities
Clean, transform, count, compare, and generate text for everyday work.
Security helpers
Generate strong passwords, inspect tokens, and safely verify checksums.
No third-party analytics scripts.
Lumio Utils is designed with internal first-party analytics. Tool inputs and file contents are not stored for analytics.
SEO pages that are useful first.
Every tool has its own landing page with the working utility, examples, FAQ, related tools, and structured content for search engines.