{{key}} {{value}}

Universally Unique - Universally Consistent

without communicating
C4 IDs are better than other identification systems in most respects. They are better for identification then filenames, URLs, and UUIDs. C4 IDs are an encoding of a SHA-512 hash that is shorter and more ergonomic than hex and yet packed with features.
  • Unique for different files.
  • The same for identical files.
  • A single ID for any number of files.
  • Anyone can produce an ID.
  • Not effected by filename.
  • Not effected by time.
  • Internet not required.
  • Eliminates duplication.
  • Files can be linked indelibly.
  • Indelible Metadata.
  • Starts with 'c4', and is 90 characters long.
  • Double click always selects the entire ID.
  • No special characters.
  • URL and Filename safe.
  • Easy to recognize in any context.
  • 64 bytes compressed.
  • Regex: c4[1-9A-HJ-NP-Za-km-z]{88}
  • Full text search friendly.
  • Easy to compare visually.
  • 7 Matching digits in a row is 1 in 2.2 trillion.
  • Cannot be forged.
  • Cannot be guessed.
  • Does not leak information.
  • Cryptographically secure.
  • Base 58 encoded SHA-512

The demo above uses javascript to identify the files you drop locally on your machine. It does not send any information to the server. Using javascript may be a little slow on large files.