Cuisdev blogPractical guides on JSON, data formats, images, PDFs and the everyday tasks our tools solve.https://cuisdev.com/enWhat is CORS and how to fix CORS errorshttps://cuisdev.com/blog/cors-errors-explained/https://cuisdev.com/blog/cors-errors-explained/CORS errors explained in plain terms, why the browser blocks the response, what preflight requests are, and how to fix the server, not the client.Sat, 03 Oct 2026 00:00:00 GMTAPIWebCron syntax explained with 30 real-world exampleshttps://cuisdev.com/blog/cron-syntax-examples/https://cuisdev.com/blog/cron-syntax-examples/Cron syntax explained field by field, with 30 copy-ready cron examples for every minute, hourly, daily, weekdays, monthly and the gotchas that break schedules.Sat, 03 Oct 2026 00:00:00 GMTDevOpsDeveloperJWT explained: structure, signing and security mistakeshttps://cuisdev.com/blog/jwt-explained-security/https://cuisdev.com/blog/jwt-explained-security/What a JSON Web Token is, how its three parts and signature work, HS256 vs RS256, and the JWT security mistakes that lead to real vulnerabilities.Sat, 03 Oct 2026 00:00:00 GMTSecurityAPIMarkdown cheat sheet: GitHub Flavored Markdown with exampleshttps://cuisdev.com/blog/markdown-cheat-sheet/https://cuisdev.com/blog/markdown-cheat-sheet/A complete Markdown cheat sheet with copyable examples: headings, emphasis, lists, links, images, code, tables, task lists and GitHub Flavored Markdown extras.Sat, 03 Oct 2026 00:00:00 GMTWritingDeveloperUnix timestamps explained: seconds, milliseconds and 2038https://cuisdev.com/blog/unix-timestamp-explained/https://cuisdev.com/blog/unix-timestamp-explained/What a Unix timestamp is, how to tell seconds from milliseconds, how to convert epoch time in JavaScript, Python and SQL, and what the 2038 problem means.Sat, 03 Oct 2026 00:00:00 GMTTimeDeveloperWebP vs AVIF vs JPEG vs PNG: which image format to usehttps://cuisdev.com/blog/webp-vs-avif-vs-jpeg/https://cuisdev.com/blog/webp-vs-avif-vs-jpeg/WebP vs AVIF vs JPEG vs PNG compared: compression, transparency, browser support and encoding speed, with a simple rule for choosing the best image format.Sat, 03 Oct 2026 00:00:00 GMTImagesPerformanceWhat is Base64 encoding and when should you use ithttps://cuisdev.com/blog/what-is-base64/https://cuisdev.com/blog/what-is-base64/What Base64 encoding is, how it turns bytes into text, why it adds 33 percent, and when to use it or avoid it, with examples in JavaScript and Python.Sat, 03 Oct 2026 00:00:00 GMTEncodingDeveloperHow to validate JSON and fix the five most common errorshttps://cuisdev.com/blog/how-to-validate-json/https://cuisdev.com/blog/how-to-validate-json/A practical guide to checking JSON syntax, reading parser error messages and fixing trailing commas, single quotes, unquoted keys, comments and invalid values.Fri, 02 Oct 2026 00:00:00 GMTJSONDeveloper