// ORIGINAL PROMPT
0 words · 0 chars
// REVISED PROMPT
0 words · 0 chars
Ready to compare
Paste two prompts above and click Compare// show differences between prompts
Compare two AI prompts side by side. Instantly highlight additions, removals, and replacements to track how your prompt wording evolves.
Ready to compare
Paste two prompts above and click CompareEnter your original prompt on the left and your revised version on the right.
Select Word, Char, or Line diff mode and Split or Unified view.
Click Compare Prompts to instantly see additions in green and removals in red.
Prompt Diff Viewer is a free browser-based tool that highlights exactly what changed between two versions of an AI prompt. Paste your original and revised prompts, choose your diff granularity, and instantly see which words were added, removed, or replaced — without installing anything.
No. All diff computation happens entirely in your browser using JavaScript. Your prompts never leave your device, making this tool safe for sensitive or proprietary prompt content.
Word mode highlights individual word changes, which is best for most prompt edits. Char mode shows character-by-character differences, useful for spotting subtle wording tweaks. Line mode treats each line as a unit, ideal for structured or multi-line prompts.
Yes. The tool handles long-form prompts including system instructions, few-shot examples, and complex multi-part prompts without any length restrictions.
Green highlights indicate text that was added in the revised prompt. Red highlights indicate text that was removed from the original. Unmarked text is unchanged between both versions.
Split view shows the original and revised prompts side by side for easy visual comparison. Unified view shows all changes in a single pane, similar to a Git diff output, which is compact and easier to copy.
Absolutely. While designed with AI prompts in mind, this tool works for any plain text — documentation drafts, email templates, content edits, and more.
A Prompt Diff Viewer is a specialized text comparison tool designed for AI practitioners, prompt engineers, and developers who need to track changes between different versions of AI prompts. As large language models (LLMs) become central to software development and content workflows, the ability to precisely document and review prompt changes has become essential.
Unlike general-purpose text comparison tools, a prompt diff viewer is tuned for the patterns common in LLM prompts: instruction blocks, persona definitions, few-shot examples, formatting directives, and constraint clauses. Understanding what changed — and why — between prompt versions is a critical part of responsible AI development.
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Prompt engineering is an iterative process. A single change — swapping "list" for "enumerate," adding a negative constraint, or restructuring the context window — can dramatically change model behavior. Without a clear record of what changed between prompt versions, it becomes impossible to:
The Prompt Diff Viewer makes this process visual and immediate. Instead of manually reading two walls of text, you get a color-coded, token-level breakdown of every change.
Different diff granularities serve different purposes in prompt engineering:
Word-level diff is the most human-readable mode. It highlights which words were replaced, added, or removed. This is the default and works well for most prompt editing scenarios, where changes tend to happen at the word or phrase level — replacing "summarize" with "provide a bullet-point summary of," for example.
Character-level diff goes deeper, showing changes at the individual character level. This is valuable when you're making subtle punctuation adjustments (adding or removing commas, colons, or quotes) that can influence how a model parses instructions. It's also useful for catching typos introduced during editing.
Line-level diff treats each line as an atomic unit. This works best for structured, multi-line prompts where you're adding, removing, or reordering instruction blocks, few-shot examples, or XML tags.
The split view displays the original and revised prompts side by side, with corresponding sections aligned. This layout makes it visually obvious how sections relate to each other and is the most intuitive format for reviewing changes in context.
The unified view collapses both prompts into a single pane, using color coding to show additions and deletions inline. This is the format familiar to developers from Git diffs and is compact, easy to copy, and well-suited for sharing in documentation or commit messages.
For the best results when comparing prompts:
As LLM-powered applications move into production, prompt management is becoming a discipline in its own right. Teams are adopting tools for prompt registries, version control, and evaluation pipelines. A prompt diff viewer fits naturally into this workflow as the first step: before you can evaluate the impact of a change, you need to clearly see what that change was.
For solo developers, the tool is equally valuable. Whether you're iterating on a system prompt for a customer service bot, refining a code generation prompt, or tweaking a creative writing assistant, having a clear visual record of your edits saves time and reduces guesswork.
Many AI prompts contain proprietary information — business logic, system designs, confidential workflows, or competitive insights. The Prompt Diff Viewer processes all text entirely in your browser. No data is transmitted to any server, logged, or stored. You can safely compare sensitive prompts without any risk of data leakage.
In practice, most prompt edits fall into a handful of categories that the diff viewer is designed to highlight:
Each of these change types is clearly visible in the diff output, whether you're working in word, character, or line mode.