SelfDevKit Blog

Learn cron syntax, build expressions with a crontab generator, and debug cron jobs that fail silently.

Use this unix timestamp converter guide with code examples in 6 languages, seconds vs milliseconds reference, and Y2038 explained.

Compare the best SQL formatter online tools and learn when offline formatting is the safer, faster choice for developers.

Learn how to use a code diff checker to compare files, read unified diff output, and spot changes fast.

Convert JSON to TypeScript interfaces automatically. Learn manual and automated approaches with real code examples.

Use an RGB color picker to find exact color values, convert formats, and write modern CSS with confidence.

An image converter transforms files between PNG, JPG, WebP, GIF, and TIFF. Learn each format and why offline conversion matters.

Learn how to format SQL queries for readability. Covers style conventions, code examples, and offline formatting tools.

Learn how a URL parser breaks URLs into components like protocol, host, path, and query strings for faster debugging.

Learn how to use an HTML formatter to beautify messy markup, minify for production, and validate your code offline.

Generate UUIDs and unique IDs for your projects. Learn which version to use, how they work, and why UUID v7 is replacing v4.

Use a hex color picker to find exact color codes, convert between formats, and check WCAG contrast.

Learn how to decode JWT tokens using desktop tools, command-line one-liners, and code in JavaScript, Python, and Go.

Learn how to convert base64 to image and back with code examples in JavaScript, Python, and Node.js, plus fixes for the most common decoding errors.

Learn how to generate a JWT secret key that actually meets RFC 7518 requirements, plus the format decisions developers always get wrong.

Learn every approach to JSON to Dart conversion: manual fromJson, json_serializable, and freezed, with real-world nested object examples.

Learn how to JSON minify for production, cut file sizes by up to 40%, and avoid the privacy risks of pasting sensitive data into online tools.

Learn how to unescape JSON strings in Python, JavaScript, and Go with code examples and debugging tips.

Learn how I use SelfDevKit to build native iOS applications like FeelClose, a long-distance couples app. From debugging Supabase APIs to decoding JWTs, see the developer tools that power mobile development.

Learn how I use SelfDevKit to build production services like Is It Visible, a mountain visibility forecasting platform. From JSON debugging to URL encoding, see the developer tools that power real projects.

Master regex with this comprehensive regex tester guide. Learn regex syntax, common patterns for validation, capture groups, and how to test expressions effectively with real-world examples.

Learn how hash generators work and when to use MD5, SHA256, SHA512, or BLAKE. Understand hashing for file integrity, password security, and API authentication with practical examples.

Learn how to base64 encode and decode text and images. Understand data URIs, when to use Base64, and how to convert images to Base64 strings for HTML, CSS, and APIs.

Learn how to generate truly secure passwords in 2025. Understand password entropy, strength analysis, and why offline generators are the only safe choice for your credentials.

Learn how to decode, validate, and debug JWT tokens securely. Understand JWT structure, algorithms, claims, and why offline decoders protect your authentication secrets.

Learn how to format, view, validate, and debug JSON data efficiently. Discover the best JSON tools for developers and why offline formatters protect your sensitive API data.

Discover why privacy-focused, offline developer tools are essential in 2025. Learn how local processing protects your API keys, JWT tokens, and sensitive data while delivering instant performance.

Master SelfDevKit from installation to advanced workflows. Learn how to use JSON tools, JWT decoder, ID generators, and 50+ developer utilities to boost your productivity while keeping your data completely private.