Guides

Longer explanations of the problems behind the tools — written to be read once and remembered, not to be skimmed for a button.

• How to read and fix broken JSON

  Almost every JSON parse error comes from one of five mistakes. Here is how to find which one, from the error message alone.

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• MD5, SHA-1 or SHA-256: choosing a hash function

  MD5 is broken and still useful. SHA-256 is the default and still not a password hash. The distinction is what the hash is protecting against.

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• Sizing and compressing images for the web

  Most slow pages are slow because of one image. Fixing it is two decisions — dimensions, then format — taken in that order.

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