This is a python wrapper of the original C implementation. (Source code from Fossil-2.6)

Fossil achieves efficient storage and low-bandwidth synchronization through the use of delta-compression. Instead of storing or transmitting the complete content of an artifact, fossil stores or transmits only the changes relative to a related artifact.

• Format
• Algorithm
• Original implementation

Other implementations:

• JavaScript (Online demo)
• C#

pip install python-fossil-delta

import fossil_delta


def main():
    delta = fossil_delta.create_delta(b'abc', b'abcdef')
    out = fossil_delta.apply_delta(b'abc', delta)
    print(out)  # --> abcdef