Code Tools
JWT decode/encode, chmod calculator, semver parser, number base converter — utilities specifically for writing and debugging code.
5 tools in this category
Chmod Calculator
Unix file permissions converter — octal, symbolic, and checkbox grid, always in sync.
JWT Decoder
Decode JSON Web Tokens — header, payload, signature.
MongoDB Query Builder
Build MongoDB find() queries visually — generate shell, Node driver, Mongoose, and pymongo code in one click.
Number Base Converter
Convert numbers between binary, octal, decimal, and hex — BigInt-safe, with bitwise ops.
SemVer Parser
Parse, compare, increment, and range-check Semantic Versioning strings.
These are the specialty tools you need ten times a year but forget the syntax for: decoding a JWT to inspect its claims, calculating the numeric form of `chmod g+rx`, checking if `^1.2.3` satisfies `1.2.4`, converting a hex constant to binary to understand a bitfield. Built for fast lookup and shareable URLs.
JWT inspection without leaking tokens
JWTs are tokens. Pasting a production JWT into a random website is a real security risk. Our JWT Decoder parses the three parts client-side and does not log or transmit the token. The JWT Encoder signs with HS256/HS384/HS512 using the Web Crypto API — the signing key stays in the browser.
chmod explained
Unix permissions pack nine bits (owner/group/other × read/write/execute) into three octal digits. 755 means the owner has all three, group and other have read+execute. Plus three special bits (setuid, setgid, sticky). Our Chmod tool converts between octal and the symbolic rwxr-xr-x representation both ways and explains the result in English.
SemVer for range compatibility
^1.2.3 matches 1.x.x but not 2.0.0. ~1.2.3 matches 1.2.x but not 1.3.0. Our SemVer tool lets you paste a version and a range spec and tells you exactly whether they satisfy — eliminating the guesswork when debugging a dependency resolution.
Frequently asked questions
Is it safe to paste a JWT here?
Yes — the JWT Decoder runs fully in your browser and never transmits the token. That said, if your JWT is still valid (not expired), treat it like a password and do not share the URL with anyone. We don't persist the token, but your browser history does.
Why is chmod `777` considered dangerous?
`777` grants read/write/execute to everyone. On a shared system, any user can modify or delete the file. Use `755` for executables, `644` for text files as a default.
Does SemVer support pre-release range matching?
Yes — `^1.2.3-alpha.1` follows npm's pre-release rules (prerelease versions only match if the base matches). Range expressions `>=1.2.3 <2.0.0 || 3.x` work as expected.
What does the Number Base tool do that a calculator can't?
It uses JavaScript BigInt, so numbers beyond 2^53 round-trip losslessly. It also shows signed/unsigned 32/64-bit two's-complement and byte-order (BE/LE) representations, which a standard calculator won't.