Fastsoft / Guide
Practical guide
Put original and revised text side by side, then inspect added, removed and unchanged lines in a unified result with line numbers.
How to use it
- Enter the original on the left and the revision on the right.
- Optionally ignore leading and trailing whitespace per line, then choose Compare.
- Review green additions, red removals and line numbers. Compare again after editing either input.
Example
Changing “Price 10” to “Price 12” produces one removed line and one added line. The changed digit is not highlighted separately.
What to know
This is line-level comparison, not character-level highlighting. Ignoring outer whitespace affects equality only. Combined input is limited to 200,000 characters and 5,000 lines; complex diffs can time out. Text is not uploaded.
Common question
Why does changing one character replace the whole line?
Each line is one comparison unit, so any change within it is shown as an old line and a new line.