Data formats
How to Base64 encode and decode on a Mac
Base64 is an encoding, not encryption. Learn Base64 vs Base64URL, what the = padding means, and the macOS Terminal commands to encode and decode text and files.
5 min read
Guides
Guides for everyday developer work
Plain answers on reading a JWT, fixing invalid JSON, Base64, Unix timestamps, checksums, and keeping your secrets out of AI prompts.
Data formats
How to convert a Unix timestamp to a date
Seconds or milliseconds, UTC or local time: how to turn a Unix timestamp into a real date on a Mac, on Linux and in JavaScript.
5 min read
Tokens and security
How to decode a JWT safely, without a website
Read the header and payload of a JWT offline, make sense of exp, iat and nbf, and know what decoding does not prove.
5 min read
Data formats
How to fix invalid JSON: the common errors
The handful of mistakes behind almost every invalid JSON error, with before and after examples and how to find the position.
5 min read
AI for developers
How to keep secrets out of AI prompts
API keys, tokens and passwords slip into AI chats inside logs and config files. What to look for, how to mask it and what to do after a leak.
5 min read
Tokens and security
MD5 vs SHA-256: which checksum to use
What a hash is, when MD5 is still fine, why SHA-256 is the default for checksums, and how to verify a download on a Mac.
5 min read
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