Instruction diff
Compare two prompt or instruction versions line by line.
Runs in this tab. The file stays here.
Highlighted diff
This runs in your browser. Nothing is uploaded.
About Instruction diff
Paste two versions of a prompt or instruction file and see exactly which words changed. It runs in your browser.
Prompts get better through a lot of small edits, and it's easy to lose track of which one made the output worse. Put the old version in the left box, the new one in the right, and a highlighted diff appears underneath: removed text in red with a strikethrough, added text in green, unchanged text plain. It's the quickest way to see what a teammate did to the system prompt, or what you actually changed between version 7 and version 9.
This is the same word-level comparison as the general text diff, with the same boxes and the same output. The difference is the setting, not the engine. Prompt edits tend to be single words ("must" to "should") or a reordered rule, and a word-level view shows both clearly where a line-level view would flag whole paragraphs. It doesn't know anything about prompts: no token counts, no comparison of model output, and no sense of which change matters.
A reformatted section shows as changed even when the meaning isn't, and a moved block can look noisier than it is. There's no ignore-whitespace option and no download of the result. Both versions stay in the tab, so it's fine to compare a prompt that has customer details in it.
How to use Instruction diff
- 1Paste the older version into Original.
- 2Paste the newer version into Changed.
- 3Read the highlighted diff: green is added, red is removed.
What it won't do
- Word-level diff only; no token counts, no line-by-line mode.
- No ignore-whitespace or case-insensitive setting.
- Two texts at a time; nothing is saved or exported.
Common questions
How is this different from the text diff tool?
It isn't, under the hood. It's the same comparison, offered on its own page for people who search for a way to compare prompts. If you already know the text diff, you already know this one.
Does it compare what the model outputs?
No. It compares the two pieces of text you paste, nothing else. To compare model answers, paste the two answers instead of the two prompts.
Can I ignore whitespace or case?
No. There are no options. Whitespace and capitalisation differences are shown as changes, so run both through the prompt formatter first if the layout is what differs.
Related tools
Why this one doesn't upload your file
There is no server to upload to. This page is a static file, and the work happens in your browser using the same graphics and WebAssembly code that renders every other site you visit. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network entirely and it keeps working. The longer explanation