The payload is self-contained, but not universal. It stores a format marker, PBKDF2 work factor, random 16-byte salt, random 12-byte IV, and authenticated ciphertext in one Base64 string. It does not store the password. Other AES tools, OpenSSL, GPG, and password managers use different formats, so they cannot automatically open this custom payload.
Encryption and decryption use your browser's Web Crypto API. Your text and password are not sent to CanDoYa. For long-term archives or high-value secrets, use a reviewed encryption product with documented recovery, backups, and key management instead of a convenience tool.