Luminus

Developer tools

Everyday utilities for building and debugging: format and validate JSON, decode JWTs, encode and decode Base64 and URLs, generate hashes, test regular expressions, parse cron expressions, and convert timestamps and colors. There's also JSON-to-CSV conversion and a text diff. All of it runs client-side, so tokens, payloads, and secrets never leave your machine.

69 free tools · no sign-up

Pretty-print, minify, and validate JSON with the error line called out.

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Convert text to Base64 and back, Unicode-safe.

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Read the header and payload of a JSON Web Token, with expiry checked.

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SHA-1, SHA-256, and SHA-512 digests, computed in your browser.

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Percent-encode or decode text and whole URLs, component by component.

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Test a pattern against sample text with live match highlighting and groups.

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Read a crontab line in plain English and see its next run times.

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Convert between Unix time and human dates, in your zone and UTC.

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Translate a color between HEX, RGB, and HSL with a live swatch.

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Turn a JSON array into CSV, or a CSV table back into JSON.

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Compare two blocks of text and see exactly what changed, line by line.

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Minify HTML, CSS, or JavaScript code to save file size.

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Format and beautify SQL queries with proper indentation.

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Convert configuration files between JSON and YAML formats.

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Encode or decode HTML entities to prevent rendering issues.

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Escape or unescape string special characters and slashes.

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Calculate octal and symbolic notations for Linux file permissions.

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Parse and analyze browser, OS, and device info from a User-Agent string.

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Design beautiful CSS linear and radial gradients visually.

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Design outer and inset CSS box shadows visually with preview.

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Design rounded borders visually for CSS custom boxes.

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Convert raw SVG code into a CSS-ready percent-encoded Data URI.

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Analyze color contrast ratios against WCAG 2.0 AA/AAA accessibility standards.

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Extract host, path, port, protocol, and query parameters from any URL.

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Query A, AAAA, MX, NS, TXT, and CNAME records using Cloudflare DoH.

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Calculate subnets, hosts, ranges, broadcast, and CIDR prefix masks.

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Generate cron schedules visually and translate to crontab lines.

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Generate visual CSS polygon clip paths for shapes and layouts.

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Generate smooth organic liquid CSS blob shapes.

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Generate smooth SVG wave divider shapes for sections.

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Searchable git commands quick reference guide.

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Searchable regex syntax reference guide.

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Searchable reference of all official HTTP status codes.

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Searchable list of file extensions and MIME content types.

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General operating systems and development editor shortcuts guide.

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Record your screen and system/microphone audio directly in-browser.

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Record audio from your microphone natively in-browser.

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Generate secure Bcrypt hashes or verify passwords against hash codes.

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Calculate secure keyed-hash message authentication codes (HMAC).

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Encrypt and decrypt text payload with secure AES-GCM password keys.

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Generate secure 2048-bit RSA Public/Private keys in PEM format.

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Generate 2FA validation codes from base32 seed keys.

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Generate cryptographically secure tokens, hex codes, or UUIDs.

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Test password entropy, length, complexity, and get strength advice.

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Generate secure BIP39 compliant 12 or 24-word passphrases.

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Find geolocation metadata for any IP address.

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Check server response headers and status codes in-browser.

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Trace redirect loops and URL paths dynamically.

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Calculate webpage source code weight in kilobytes.

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Simulate a crawler bot extracting plaintext page weights.

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Extract Facebook OG and Twitter meta card tags from any page.

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Simulate custom mobile viewport rendering for layout testing.

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Detect your public IPv4 and IPv6 addresses side-by-side in real-time.

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Detect private local IP addresses leaking through WebRTC connections.

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Learn how to test and verify if your DNS queries leak outside your VPN.

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Check Canvas, WebGL, AudioContext, and system font footprint uniqueness.

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Test your download connection transfer speed client-side.

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Check round-trip ping latency to AWS, Cloudflare, and Google servers.

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Inspect HTTP request headers and client environment variables.

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Verify if your IP address is blacklisted on major anti-spam databases.

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Trace SMTP hops and check SPF/DKIM flags from raw email headers.

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Inspect a domain's DNS MX mail servers and SPF safety validation records.

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Track screen resolution, viewport bounds, and pixel ratios in real-time.

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Simplify resolution dimensions into mathematical aspect ratios (e.g. 16:9).

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Calculate display pixel density (PPI) based on size and resolution.

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Extract emails, URLs, IPs, and card numbers from raw unstructured text.

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Encrypt and decrypt text payload using simple bitwise XOR calculations.

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Validate and format raw XML markup structures with indentation.

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Format and indent TOML configuration syntax parameters.

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Why use these developer tools?

  • Decode JWTs, hash strings, and inspect Base64 without pasting sensitive data into a third-party server.
  • Live feedback: the regex tester highlights matches as you type and the cron parser translates an expression into its next run times.
  • Handles the conversions you hit daily — Unix timestamps to readable dates, hex to RGB/HSL, and JSON to CSV and back.

Frequently asked questions

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