Tools
Produce MD5, SHA-1, SHA-256, SHA-512 and bcrypt.
A hash is a one-way digest. MD5 and SHA-1 are weak; use SHA-256 for integrity and bcrypt for passwords.
Bcrypt uses a new salt every time, so the same text hashes differently. That is expected.
SHA-256 is enough for file integrity and git-style fingerprints. Store passwords with bcrypt (or Argon2, not here); salt and cost resist brute force.
No. Encryption can be reversed. A hash is not designed to recover the input.
For legacy checksums, yes. It is collision-prone; do not use it in new designs.
Legacy interop. TLS and git have moved away from it.
The work factor; higher is slower. The tool uses a reasonable default.
The hash API runs on the server. Do not hash secrets you would not send; prefer a local tool.