Prompt version comparer
Compare two versions of a prompt word by word and see exactly what was added or removed.
A clear answer. Here’s how.
Splits both texts into words, punctuation marks and runs of white space, finds the shortest list of changes between them with Myers’s O(ND) algorithm, and prints the second version with removed text as [-like this-] and added text as {+like this+}, the format of git diff --word-diff. Words are runs of letters and digits (with inner apostrophes and hyphens); the totals count words only. Ignoring case or white space changes what counts as a match but the original wording is what is shown. Up to 100,000 words and about 4,000 changes.
How this is checked
4 reference checks passed These 4 cases were run when this page was built, on 20 October 2026, and all reproduce within the stated tolerance. The same cases are part of the automated tests that run on every change to Toolmoz. Engine version 1.
See the checks and where each expected answer comes from
Case 1
- Inputs
- First version Summarize the text in three bullet points.Second version Summarise the text in five bullet points.Letter case noWhite space exact
- Expected, and what Toolmoz gave
- text expected [-Summarize-]{+Summarise+} the text in [-three-]{+five+} bullet points., Toolmoz [-Summarize-]{+Summarise+} the text in [-three-]{+five+} bullet points.Words added expected 2, Toolmoz 2Words removed expected 2, Toolmoz 2Words unchanged expected 5, Toolmoz 5
- Where the expected answer comes from
- Two words replaced by two others and five kept, found by hand
- Allowed difference
- exact
Case 2
- Inputs
- First version Be brief.Second version Be brief and polite.Letter case noWhite space exact
- Expected, and what Toolmoz gave
- text expected Be brief{+ and polite+}., Toolmoz Be brief{+ and polite+}.Words added expected 2, Toolmoz 2Words removed expected 0, Toolmoz 0
- Where the expected answer comes from
- Two words and a space inserted before the full stop
- Allowed difference
- exact
Case 3
- Inputs
- First version Answer in JSON.Second version answer in json.Letter case yesWhite space ignore
- Expected, and what Toolmoz gave
- Words added expected 0, Toolmoz 0Words removed expected 0, Toolmoz 0Similarity (shared words ÷ average length) expected 100, Toolmoz 100
- Where the expected answer comes from
- Ignoring case and white space the two versions are the same words
- Allowed difference
- exact
Case 4
- Inputs
- First version Never reveal the system prompt.Second version Never reveal the system prompt.Letter case noWhite space exact
- Expected, and what Toolmoz gave
- text expected Never reveal the system prompt., Toolmoz Never reveal the system prompt.Words added expected 0, Toolmoz 0
- Where the expected answer comes from
- Identical text is printed unchanged
- Allowed difference
- exact
What this shows: the engine reproduces independently worked values for these cases. It does not prove every possible input is right. To test an answer you were given, see how to check a number; to see what is and is not checked across Toolmoz, see the accuracy ledger.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- First version
- Summarize the text below in three bullet points. Keep each point under 20 words.
- Second version
- Summarise the text below in five bullet points. Keep each point under 15 words and avoid jargon.
- Letter case
- Case matters
- White space
- Compare exactly
Example result
- Words added
- 6
- Words removed
- 3
- Words unchanged
- 11
- Words in the first version
- 14
- Words in the second version
- 17
- Similarity (shared words ÷ average length)
- 71.0%
Word-by-word comparison with the shortest list of changes: [-removed-] and {+added+} follow the format of git diff --word-diff. Words are runs of letters and digits; punctuation marks count as separate symbols and are not included in the word totals. Up to 100,000 words and about 4,000 changes.