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Prompt Diff

Paste two system prompts side by side with line-level add/remove highlights. Great for A/B logs and iteration reviews.

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Compare two prompt versions with line-level highlights. Handy for A/B tests and iteration logs.

Prompt A (before)

Prompt B (after)

Diff view

−You are a helpful assistant.
−Answer in a friendly tone.
+You are a senior engineer.
+Be concise and technical.

Notes

When to use

Track system prompt edits; green + is new in B, red − was removed from A.

Paste two system prompts side by side with line-level add/remove highlights. Great for A/B logs and iteration reviews.

Quick start

  1. Paste A and B

    Left is before; right is after.

  2. Read diff

    + is new in B; − was removed from A.

vs Text Diff

Same engine; defaults and copy target prompt iteration workflows.

Features and use cases

Diff two prompt versions with highlighted add/remove lines for system/user and few-shot iterations.

Use in prompt versioning, review of prompt changes, and scoping regression tests.

Typical Workflow

The Prompt Diff tool is most commonly used for AI model debugging. Developers first record the original prompt's performance, then paste the modified version for comparison. By inspecting line-by-line changes, they quickly identify key modifications affecting the output. This process often repeats until satisfactory results are achieved.

During team collaboration, members can compare different optimization proposals side-by-side. The color-coded differences visually demonstrate each version's strengths and weaknesses, avoiding miscommunication. Particularly in remote work scenarios, this visual comparison significantly reduces communication overhead and ensures alignment on modification intent.

Examples

Tone tweak

Input

helpful assistant → senior engineer

Output

Line-level diff

FAQ

Word-level diff?

Line-level only; use a dedicated diff tool for finer granularity.

Why aren't some semantic changes highlighted?

The tool performs strict line-by-line text comparison, only marking identical characters as unchanged. If you modify synonyms or rearrange sentences while keeping keywords, manual semantic review is needed. For major changes, use version numbers to distinguish prompts rather than relying solely on line-level diff.