This encoding is used in Hellnet to represent binary values in human-readable and easily portable form. It's designed to be human and machine readable, compact and pronounceable. You can read about the encoding here.
Example of URI with crockford-encoded string:
hell://crypt/7T0V608MQDSCA8R3V6SG6H3HFVCXM7ZM63F2GFQC1M1MRFDJGPH9N4KNXA6RF6QHDSP3904JYYHHEGDJCANE3RWWX58VYA9KS4PQVZ5NEYA68MQTZRW2Y8PB75QA293E1S7NEMTHH6MT52S20X4ADCNBB457FHFY8W6RRZQ52MNW7NB8ZXV3ZM9NKW26QHP1V80NF56M7QJ4DVMN15V8RHKYGSWXEQDBE76K36N5MTFCK1K0MRP3NT841YV50Z7SFM134K5V2SNR5P033V9Y7FGZ4CRYPKJ0M9D9XA7VX9ZGW