Prompt Diff Documentation - PromptAsCode

Overview

The Prompt Diff tool provides a GitHub-style visual comparison between two prompt versions. See exactly what changed between versions with syntax highlighting for additions, deletions, and modifications. Track token count changes to understand how edits affect costs.

Visual Diff

Clear line-by-line comparison

Split/Unified Views

Choose your preferred layout

Token Tracking

See token count changes

How to Use

1
Enter Original Prompt - Paste your original/previous version of the prompt in the left editor.
2
Enter Modified Prompt - Paste the new/modified version of the prompt in the right editor.
3
Click Compare - Generate the diff view showing all changes between the two versions.
4
Review Changes - Use the diff viewer to see additions (green), deletions (red), and unchanged lines.
5
Toggle View Mode - Switch between split view (side-by-side) and unified view (inline) as preferred.

View Modes

Split View

Displays original and modified prompts side-by-side. Best for comparing longer prompts where you want to see the full context of both versions simultaneously.

┌─────────────────┬─────────────────┐
│  ORIGINAL       │  MODIFIED       │
├─────────────────┼─────────────────┤
│  Line 1         │  Line 1         │
│- Removed line   │                 │
│  Line 3         │  Line 3         │
│                 │+ Added line     │
└─────────────────┴─────────────────┘

Unified View

Displays changes inline with deletions and additions marked. Ideal for reviewing changes sequentially and understanding the flow of modifications.

  Line 1
- Removed line
  Line 3
+ Added line
  Line 5

Diff Features

Change Highlighting

Green (+) - Added lines
Red (-) - Removed lines
Gray - Unchanged lines
Yellow highlight - Modified within line

Statistics Panel

The diff view shows key statistics:

Lines Added: Number of new lines in modified version
Lines Removed: Number of lines deleted from original
Lines Modified: Lines that changed but weren't fully replaced
Token Change: Difference in token count between versions

AI Expert Use Cases

Prompt Version Control

Use Prompt Diff to review changes before committing new prompt versions. This ensures you understand exactly what changed and can identify any unintended modifications.

A/B Test Analysis

When running A/B tests with different prompt variants, use Prompt Diff to document the exact differences between test versions for accurate attribution of results.

Team Code Review

Share diff views with team members when reviewing prompt changes. The visual format makes it easy to discuss specific modifications and their potential impact.

Debugging Regressions

When prompt quality degrades, compare the current version against a known-good version to identify which changes may have caused the regression.

Cost Impact Analysis

Track token count changes between versions to understand how prompt modifications affect API costs. Small wording changes can sometimes significantly impact token usage.

Tips & Best Practices

Pro Tips

Use unified view for quick reviews, split view for detailed analysis
Pay attention to token count changes - they affect costs
Document why changes were made alongside the diff
Compare against your best-performing version when optimizing
Use diff before deploying any prompt changes to production

Best Practices for Prompt Changes

Make small, incremental changes for easier tracking
Test each change individually before combining
Keep a changelog of significant prompt modifications
Review diffs with someone else for fresh perspective