AES Mode Comparison
See, visually, why ECB mode is unsafe — the same repeating pattern in the input stays visible after "encryption", while CBC and GCM hide it completely.
About this tool
ECB encrypts each block independently, so identical input blocks always produce identical output blocks — patterns in the plaintext remain visible. Browsers deliberately don't offer ECB through Web Crypto, because it's unsafe, but it can be built exactly from what they do offer: encrypting a single block with CBC and an all-zero IV gives AES(block XOR 0), which is precisely ECB's per-block encryption. So the ECB picture is real AES-ECB output, not a simulation. Each 16-byte block of the data is drawn as one pixel, coloured by its first three bytes, so identical blocks show up as identical colours. CBC chains each block with the previous one's ciphertext, and GCM (used by the site's own AES tool) additionally authenticates the data — both destroy the visible pattern entirely.