Version reusable system and user prompt templates with {{variables}}, run a test-case input matrix, diff versions line-by-line and estimate batch cost.
Renders {{variable}} templates, line diffs and rough token/cost math (~4 chars per token) locally in your browser. Stores no API keys, calls no external LLM endpoints and runs no model evaluations.
Fill each {{variable}} per row and optionally check must-include keywords. Any blank variable or leftover {{placeholder}} is flagged immediately.
No test rows yet. Click Add test row to test variable combinations.
Save at least two version snapshots (such as v1 and v2) to compare added (+) and removed (-) lines.
No saved templates yet. Save a version snapshot above to store it in your library.
Saved in this browser under the key prompt-workbench.v1. Download a backup often.