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Mastcall Tools

Developer tools

Format JSON, encode Base64, generate QR codes, passwords and UUIDs. 8 free tools.

Image to Base64Get a data URL for HTML or CSS, or turn Base64 back into an image file.JSON formatterBeautify, validate or minify JSON, privately.Base64 encode / decodeEncode or decode Base64 text with UTF-8 support.URL encode / decodePercent-encode or decode URLs and query parameters.UUID generatorRandom v4 UUIDs, up to 1000 at once.Password generatorStrong random passwords, generated on your device.QR code generatorTurn a link or text into a QR code that never expires.SHA-256 hashHash text or files with SHA-256, SHA-1, SHA-384 or SHA-512.

Guides

Developer tools · 23 Oct 2026How to Check the SHA-256 Hash of a File (Windows, Mac, Linux)Check a file's SHA-256 hash with certutil or PowerShell on Windows, shasum on Mac, sha256sum on Linux, or in your browser. Verify downloads properly.Developer tools · 23 Oct 2026How to Convert an Image to a Base64 String (and Back)Convert any image to a Base64 string or data URI for HTML, CSS and JavaScript, decode Base64 back to an image, and know when the size overhead is worth it.Developer tools · 23 Oct 2026How to Create a Strong Password You Can Actually ManageLength beats complexity. Learn how long a password should be, how passphrases work, and how a password manager makes strong passwords painless.Developer tools · 23 Oct 2026How to Decode a Base64 Encoded String (Linux, JS, Python)How to decode a Base64 encoded string online or with Linux, PowerShell, JavaScript atob/btoa and Python, and why Base64 is not encryption.Developer tools · 23 Oct 2026How to Decode a URL Encoded String (%20 and More Explained)Decode URL encoded strings like %20 and %3A online or in JavaScript, Python, Java and C#. Learn encodeURIComponent, + vs %20 and query strings.Developer tools · 23 Oct 2026How to Generate a UUID: Online, Python, JavaScript, SQL & ExcelHow to generate a UUID online or in Python, JavaScript, Java, PostgreSQL, Linux and Excel, plus UUID v4 vs v7 and what a Minecraft UUID really is.