Learning & reference
Everything you need to know about files, cross-platform
Practical, visual references for QA and developers — what breaks between operating systems, how file systems actually behave, and copy-paste commands to generate the exact files and certificates you need for testing. No fluff, no sign-up.
Filename & path compatibility
Which characters, reserved names (CON, NUL), path separators, trailing dots,
Unicode and zero-byte files break when files move between Windows, macOS and Linux — as a scannable ✓/✗ matrix.
File systems explained
POSIX, NTFS, APFS, ext4, FAT32/exFAT, SMB, NFS and NAS — what each one is, its file-size and path limits, case sensitivity, permissions model, and the gotchas that bite QA and backups.
Compare file systems →Generate test files (CLI)
Copy-paste commands to create a large file, thousands of small files, unique content per file, and checksums — on Windows (PowerShell/CMD), macOS and Linux. Every command has an Explain button.
Get the commands →Crypto & certificates
Self-signed SSL/TLS certificates, PEM/DER/PFX conversion, key and CSR generation, file hashing (SHA-256, SHA-1, MD5, CRC32), encryption with OpenSSL/GPG, and password-protected ZIPs — explained.
Get the commands →QA test-string library
Unicode, emoji, right-to-left, zero-width, combining marks, SQL/XSS injection and other "naughty strings" to paste into any field to break bad input handling. Copy one string or a whole category.
Open the string library →Client-side dev tools
Decode a JWT, format & validate JSON, Base64 encode/decode, hash text, generate UUIDs, convert epoch timestamps and encode URLs — all in your browser, nothing sent to a server.
Open the toolbox →Need the actual files? Every reference here pairs with real, downloadable test files — each with a published SHA-256 and a note on the exact bug it catches.