Developers
45 tools
The utilities a developer reaches for between commits, all running in your browser so the payload you paste — a JWT, an API response, a config blob — never touches a server. Format and validate JSON, convert it to CSV, YAML or TypeScript types, decode a JWT, test a regular expression against live input, read or build a cron expression, generate UUIDs and ULIDs, work out chmod bits, and convert between Base64, hex and colour formats.
No tools match your search.
Frequently asked questions
Does the JSON, JWT or other data I paste get sent to a server?
No. These tools are JavaScript running in your browser, so whatever you paste is parsed on your own machine and never uploaded. That matters when the input is a production API response or a token — you can use them on internal data without it leaving your device.
Is Base64 a form of encryption?
No, and treating it as one is a common mistake. Base64 is reversible encoding with no key: anyone can decode it back to the original bytes instantly. It exists to move binary data through text-only channels, not to hide it. If you need something kept secret, encrypt it — Base64 a password and it is still plaintext to anyone who sees it.
Which UUID version should I generate?
v4 (random) is the safe default for most IDs — unpredictable and collision-resistant. v5 derives a stable UUID from a namespace and name, so the same input always yields the same ID. v1 embeds a timestamp and MAC address. If you want time-ordered IDs that index well in a database, a ULID sorts chronologically while staying unique.
Does the JWT decoder verify the token signature?
No. It decodes the header and payload so you can read the claims, but decoding is not verification. A JWT is only Base64url-encoded, not encrypted, so anyone can read it; confirming it was actually issued by your server requires checking the signature against the secret or public key, which happens on your backend.