Someone has just linked you this page. That means you're likely looking at some kind of modern ciphertext (Probably AES).
Modern encryption aims to create ciphertext indistinguishable from random data (Meaning
high entropy), is usually transported in base64 (In this context), and often (Not always) carries data multiples of common block sizes (8 or 16 bytes) so they'll commonly look like:
txSOyOLSi38PpHm3ObuxSg==hRYb0pqmgX42rLwwn9SKO3JpV4/6pDaYKKsOczyI78DkVwsHMQnESqOsaUJ5MS+F3NMn0g==+jbiQuaXrkqbJHn7dxN8QA==
That isn't a straightforward question.
- While AES is the most common, it could be any number of different modern ciphers which would all look the same.
- If text was encrypted on site #1, then it's VERY unlikely that site #2 will be able to decrypt it. So you'll need to find the exact site (Or cipher and settings) used.
- It requires a password. That could mean an explicit literal password you need to find out, or a placeholder password a specific site uses if one wasn't entered.
- If it wasn't explicitly intended to be solved, it's very unlikely it will be able to be decrypted (The entire point of encryption).
- https://corgi.rip/dive to try the most common sites and defaults.
- Look for context/clues for the cipher used, google the most common sites. Try and find ones matching the format.
- Bruteforce passwords with the above programs if no default site settings work.
- Make sure the creator understands the difficulty and ambiguity using "AES" means and has playtested accordingly.
- If your ciphertext starts with "Salted_ (U2FsdGVkX1 in base64) it's salted OpenSSL. Use this to bruteforce, but note you don't know the cipher, nor settings (KDF, IV, etc) from the ciphertext alone.