MD5 - 128-bit hash. Fast but not collision-resistant. Use for checksums, not security.
SHA-256 - 256-bit hash from the SHA-2 family. Widely used in security applications.
SHA-512 - 512-bit hash from the SHA-2 family. Higher security margin than SHA-256.
All hashing is done client-side in your browser. No data is sent to any server.